JP2009001221A - Gas generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas generator capable of reducing the manufacturing time and cost. <P>SOLUTION: A housing 11 is separated to two chambers by a partition wall 12, one chamber becomes a combustion chamber 13 and the other chamber becomes a coolant chamber 15. In the coolant chamber 15, a large number of steel balls 16 as coolant materials are filled. The combustion gas generated in the combustion chamber 13 is cooled and filtered by the steel balls 16. By use of the steel balls 16, the manufacturing time and the manufacturing cost can be reduced as compared with a conventional filter. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gas generator that can be used in an air bag device of an automobile.

  In an automobile airbag device, a pyrotechnic gas generator (pyro inflator) using a combustion gas of a gas generating agent as a gas source is used. In this pyrotechnic gas generator, high-temperature combustion gas is cooled, and mist contained in the combustion gas (a solid component in the gas generating agent generated by the combustion of the gas generating agent, for example, a metal component). A coolant filter is used to filter and collect water.

As this coolant filter, a metal wire (usually stainless steel wire) is cut into plain strips or twilled wire strips of appropriate size and wound in multiple cylinders. There are known ones obtained by integrating a plurality of wire meshes into a cylindrical shape, a product having a plurality of wire meshes integrated into an arc shape or a cylindrical shape, and the like.
JP 11-348712 A JP 2005-193762 A JP-A-6-55991 JP-A-1-293112

  Conventional coolant filters are complex and time consuming to manufacture, and are the most expensive gas generator components. Therefore, there is a problem that the manufacturing time of the entire gas generator including the manufacturing time of the coolant / filter becomes longer, and the manufacturing cost of the gas generator itself is increased.

  The present invention uses an iron ball or steel ball that is inexpensive and easy to manufacture as a coolant material, so that the manufacturing time of the entire gas generator including parts can be greatly shortened, and the manufacturing cost is also reduced. A gas generator is provided.

  As a means for solving the problems, the invention of claim 1 has a combustion chamber filled with a gas generating agent and a coolant chamber filled with a coolant material in a housing having a gas discharge port, and the coolant chamber. The gas generator is provided with a plurality of metal spheres made of metal having a melting point sufficiently higher than the combustion temperature of the gas generating agent.

  In the gas generator of the present invention, a large number of metal balls are used in place of the conventional cylindrical body as a coolant material for cooling and filtering the high-temperature combustion gas generated by burning the gas generating agent. Has been. Combustion gas generated from the combustion chamber passes through gaps between a large number of metal spheres and reaches a gas discharge port. In this process, the combustion gas comes into contact with the metal spheres and is cooled, and the mist is adhered and held on the surfaces of the metal spheres.

  The metal sphere is made of a metal having a melting point sufficiently higher than the combustion temperature of the gas generating agent, and an iron ball, a steel ball, or the like can be used.

  Steel used as a material for the steel ball is well known, carbon steel [low carbon steel (C content is about 0.3 mass% or less; medium carbon steel (about 0.3 to 0.7 mass%); high carbon steel (about 0.7 mass%) And the like), alloy steel (low alloy steel, medium alloy steel, high alloy steel), nickel chrome steel, nickel chrome molybdenum steel, chrome steel, chrome molybdenum steel, manganese steel, gray cast iron steel and the like.

  The metal sphere is preferably a true sphere in order to make the gap between the spheres uniform, but is not limited thereto. Moreover, in order to adjust the space | interval between spheres, what formed the processus | protrusion and groove | channel on the spherical surface may be used.

  When the diameter of the metal sphere is large, the gap between the spheres is increased, and the gas discharge performance (air permeability) is improved (although pressure loss is reduced), but the filtration / cooling effect is reduced. On the other hand, if the diameter is small, the gap between the spheres becomes small, and the gas discharge performance (breathability) decreases (pressure loss increases), but the filtration / cooling effect improves.

  Therefore, the diameter of the metal sphere is not particularly limited, and can be selected in consideration of performance required for the gas generator and the size of the gas generator (such as the size of the housing and the coolant chamber).

  In order to make the performance of the coolant material uniform, it is desirable that the metal balls used in one gas generator have the same size and material. However, the coolant chamber is divided into a plurality of chambers, and the diameter and Spheres of different materials may be filled.

  For example, a sphere having a larger diameter (and / or a material having high thermal conductivity) is closer to the combustion chamber, and a smaller diameter (and / or a material having higher thermal conductivity is closer to the gas outlet). ) Can be filled with spheres.

  In the production of the gas generator of the present invention, when filling the metal sphere, a method of pouring into a coolant chamber having an opening before closing, and filling it closely by applying vibration from the outside, a plurality of cylinders For example, a filling method using an auxiliary device for filling can be applied.

  The gas generator of the present invention can be used in a single type gas generator having one igniter, one combustion chamber, two igniters, and two dual type gas generators having two combustion chambers.

  According to a second aspect of the present invention, as another solution to the problem, the gas generation according to the first aspect, wherein the coolant chamber is a space surrounded by at least one of a fixed wall and a movable partition wall and a housing inner wall surface. Provide a bowl.

  The coolant chamber can be formed by, for example, a housing inner wall surface, a combustion chamber outer wall surface, and a movable retainer. The shape of the retainer varies depending on the shape of the housing and the arrangement of the combustion chamber, but can be a disk shape, a donut shape, or the like. Using a movable retainer in this manner is preferable because the volume of the coolant chamber can be increased or decreased in accordance with the amount of coolant material charged.

According to a third aspect of the present invention, as another means for solving the problem, the total pressure loss at an air flow rate of 1 m ³ / min of a coolant material made up of a large number of metal balls filled in the coolant chamber is 0.1 to 100 kPa. A gas generator according to claim 1 or 2 is provided.

  If the coolant is filled too densely, the combustion gas may not be easily discharged from the gas discharge port, but by adjusting the pressure loss within the above range, the gas discharge and cooling and filterability can be improved. It can be maintained in good balance. The measurement of the pressure loss in the present invention is based on the method disclosed in paragraph No. 67 of FIG.

  According to a fourth aspect of the present invention, as another means for solving the problem, the diameter of the metal sphere used as the coolant material is in a range of 1.0 to 10.0 mm. A gas generator is provided.

  When there are protrusions on the surface of the metal sphere, the dimensions are the dimensions of the surface excluding the protrusions.

  Since the gas generator of the present invention uses a large number of metal balls as the coolant material instead of the conventional coolant filter, the manufacturing time of the entire gas generator including the manufacturing time of the coolant material is shortened. The coolant material itself can be manufactured very easily. For this reason, since the price of a coolant material can be reduced, the manufacturing cost of the whole gas generator can be reduced.

  The gas generator of the present invention uses a metal sphere as a coolant material. By using a metal sphere instead of a known coolant filter made of a metal wire or the like, the gas generator can also be used for a known gas generator. It can be easily applied as it is or by adding a required member such as a partition wall. Hereinafter, an embodiment of a gas generator having a typical housing shape will be described.

(1) Gas Generator in FIG. 1 FIG. 1 has a cylinder-shaped housing (a shape in which the axial length of the housing is sufficiently longer than the diameter), which is an embodiment of the gas generator 10 of the present invention. 1 is a schematic cross-sectional view of a gas generator 10 in a vertical direction.

  The housing 11 is divided into two chambers by a partition wall 12 that is movable in the axial direction. As the partition wall 12, a well-known retainer can be used as a part of the gas generator.

  One chamber is a combustion chamber 13, and an electric igniter 13 is fixed to the end wall 11a, and the internal space is filled with a known gas generant molded body (not shown). .

The other chamber is a coolant chamber 15 and is filled with a large number of steel balls 16 serving as a coolant material. A plurality of gas discharge ports 17 are formed on the side surface of the housing 11 which is the outer wall of the coolant chamber 15. The volume of the coolant chamber 15 is about 12.8 cm ³ , and the diameter of the steel ball 16 is about 3.2 mm.

  A plurality of through holes 18 are formed in the partition wall 12, and the plurality of through holes 18 are closed from the combustion chamber 13 side by an aluminum tape (not shown).

The total pressure loss at an air flow rate of 1 m ³ / min in the coolant chamber 15 filled with a large number of steel balls 16 is about 2.8 kPa.

  The gas generator 10 of FIG. 1 can be assembled as follows, for example. The housing 11 is prepared by closing one end side with an end wall 11b and opening the other end side. First, a required amount of steel balls 16 is filled with the end wall 11b side down. At this time, vibration is applied from the outside, and the whole is filled while vibrating.

  Next, the partition wall 12 is pushed in and fixed at a predetermined position. The partition wall 12 is a disc-shaped one having an outer diameter that is the same as or slightly larger than the inner diameter of the housing 11, or one having a cylindrical wall that can be pressed against the inner wall surface of the housing 11 at the peripheral edge of the disc. Can be used.

  Next, the combustion chamber 13 is filled with a required amount of the gas generant molded body. Thereafter, the opening is closed by the end wall 11a, and the electric igniter 14 is attached from the hole provided in the central portion of the end wall 11a.

  Next, the operation when the gas generator 10 of FIG. 1 is applied to an automobile airbag system will be described.

  The igniter 14 is connected to a control unit (not shown) mounted on the vehicle. When the automobile collides and receives an impact, the operation signal is received from the control unit, the igniter 14 is activated and ignited, and a flame or the like is emitted in the direction of the arrow in FIG. The agent is ignited and burned to generate combustion gas.

  The combustion gas generated in the combustion chamber 13 breaks the aluminum tape at a high temperature and flows into the coolant chamber 15 from the through hole 18. The combustion gas is cooled in the process of passing between a large number of steel balls 16, and the mist is attached to the surface of the steel balls 16.

  Thereafter, the cooled gas from which the mist has been collected is discharged from the gas discharge port 17 to inflate the airbag.

  In the gas generator 10 of FIG. 1, the discharge direction of the flame or the like from the igniter 14, the filling space (combustion chamber 13) of the gas generant molded body, and the coolant chamber 15 exist on the coaxial line. The cooling effect by the steel balls 16 in the chamber 15 is high.

(2) Gas Generator in FIG. 2 FIG. 2 shows another embodiment of the gas generator 100 of the present invention, which is a gas generator having a disk-shaped housing (the housing has a longer diameter than the axial length). 2 is a schematic cross-sectional view of the vessel 100 in the vertical direction.

  In the housing 101, a diffuser shell 102 and a closure shell 103 are combined at their flange portions and integrated by welding.

  A central cylinder 104 is disposed at the center position in the housing 101. The upper end opening side and the lower end opening side of the central cylinder 104 are fixed to the ceiling surface and the bottom surface of the housing 101. The inside of the central cylinder 104 is an enhancer chamber 105, and a plurality of enhancer holes 107 closed from the inside with aluminum tape are formed on the peripheral wall surface. The enhancer chamber 105 is filled with an enhancer agent (not shown). An electric igniter 114 is attached to the opening side of the enhancer chamber 105.

  A movable annular partition wall 112 is fitted in the central cylinder 104, and a space outside the central cylinder 104 is separated into two chambers in the housing 101.

  One chamber (the lower chamber in the drawing) is a combustion chamber 113, and the internal space is filled with a gas generant molded body (not shown).

The other chamber (the upper chamber in the drawing) is a coolant chamber 115 and is filled with a number of steel balls 116 serving as coolant materials. A plurality of gas discharge ports 117 are formed on the side surface of the diffuser shell 102 that is the outer wall of the coolant chamber 115. The volume of the coolant chamber 115 is about 18.3 cm ³ , and the diameter of the steel ball 116 is about 3.2 mm.

  A plurality of through holes 118 are formed in the annular partition wall 112, and the plurality of through holes 118 are closed from the combustion chamber 113 side by an aluminum tape (not shown).

The total pressure loss at an air flow rate of 1 m ³ / min in the coolant chamber 115 filled with a large number of steel balls 116 is about 4.0 kPa.

  The gas generator 100 in FIG. 1 is a stage before the diffuser shell 102 and the closure shell 103 are welded and integrated, and after fixing one end opening side of the central cylinder 104 to the diffuser shell 102, the steel ball 116 is filled. The annular partition wall 112 is fitted and fixed.

  Next, the operation when the gas generator 100 of FIG. 2 is applied to an automobile airbag system will be described.

  The igniter 114 is connected to a control unit (not shown) mounted on the vehicle. When the automobile collides and receives an impact, an activation signal is received from the control unit, the igniter 114 is activated and ignited, and a flame or the like is emitted in the direction of the arrow in FIG. The agent is ignited and burned to generate flames and high-temperature gas.

   Flames, high-temperature gas, and the like generated in the enhancer chamber 105 break the aluminum tape and flow into the combustion chamber 113 from the enhancer hole 107, ignite and burn the gas generant compact, and generate combustion gas.

  The combustion gas generated in the combustion chamber 113 breaks the aluminum tape at a high temperature and flows into the coolant chamber 115 from the through hole 118. The combustion gas is cooled while passing between a large number of steel balls 116, and the mist is attached to the surface of the steel balls 116.

  Thereafter, the cooled gas from which the mist has been collected is discharged from the gas discharge port 117, and the airbag is inflated.

The longitudinal cross-sectional view of the gas generator of this invention. The longitudinal cross-sectional view of the gas generator of this invention of another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Gas generator 11 Housing 12 Partition wall 13 Combustion chamber 14 Igniter 15 Coolant chamber 16 Steel ball 17 Gas discharge port

Claims (3)

  A housing having a gas discharge port has a combustion chamber filled with a gas generating agent and a coolant chamber filled with a coolant material, and the coolant material filled in the coolant chamber contains the gas generating agent. A gas generator which is a large number of metal spheres made of a metal having a melting point sufficiently higher than the combustion temperature.   The gas generator according to claim 1, wherein the coolant chamber is a space surrounded by at least one of a fixed wall and a movable partition wall and an inner wall surface of the housing.   The gas generator according to claim 1 or 2, wherein a diameter of a metal sphere used as the coolant material is in a range of 1.0 to 10.0 mm.

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