Gas generator
A gas generator includes a housing main body made of metal, a holder assembly, and an igniter. The holder assembly includes a holder portion made of metal and a connector portion made of resin. The holder portion includes a first barrel portion and an annular projection. The connector portion includes a second barrel portion and a cylindrical portion. The cylindrical portion is inserted in the housing main body and externally attached to the first barrel portion. As a portion of the housing main body corresponding to the cylindrical portion is decreased in diameter, the cylindrical portion is compressed by being sandwiched between the portion of the housing main body decreased in diameter and the first barrel portion so as to seal a gap between the housing main body and the first barrel portion.
1. A gas generator comprising:
a cylindrical housing main body made of metal, the housing main body containing a combustion chamber where a gas generating agent is accommodated;
a holder assembly inserted in an opening end in an axial direction of the housing main body, the holder assembly including a hollow opening like a through hole, the hollow opening extending along a direction in parallel to the axial direction of the housing main body; and
an igniter including an ignition portion where an ignition agent is accommodated and a terminal pin connected to the ignition portion, at least a part of the igniter being arranged in inside of the hollow opening while the ignition portion is located on a side of the combustion chamber and the terminal pin is located opposite to the side of the combustion chamber, wherein
the holder assembly includes
a holder portion made of metal, the holder portion being located on the side of the combustion chamber, the holder portion receiving and holding the igniter, and
a connector portion made of resin, the connector portion being located opposite to the side of the combustion chamber, the connector portion receiving a connector connected to the terminal pin,
the holder portion includes
a first barrel portion in a cylindrical shape that defines the hollow opening, and
an annular projection that projects from the first barrel portion along a radial direction of the housing main body,
the connector portion includes
a second barrel portion in a cylindrical shape that defines the hollow opening, and
a cylindrical portion that extends from the second barrel portion toward the combustion chamber,
the cylindrical portion is inserted in the opening end of the housing main body and externally attached to a portion of the first barrel portion located opposite to the side of the combustion chamber when viewed from the annular projection, and
a portion of the housing main body corresponding to the cylindrical portion is decreased in diameter radially inward, so that the cylindrical portion is compressed by being sandwiched between the portion of the housing main body decreased in diameter and the first barrel portion to seal a gap between the housing main body and the first barrel portion.
2. The gas generator according to claim 1 , wherein
the cylindrical portion is larger in inner diameter than the second barrel portion and an annular stepped surface that connects an inner circumferential surface of the second barrel portion and an inner circumferential surface of the cylindrical portion to each other is provided in the connector portion, so that a first chamber defined by the annular stepped surface and the inner circumferential surface of the cylindrical portion is provided at an axial end of the connector portion located on the side of the combustion chamber, and
the first barrel portion is inserted in the first chamber and an axial end surface of the first barrel portion located opposite to the side of the combustion chamber abuts on the annular stepped surface.
3. The gas generator according to claim 1 , wherein
the second barrel portion is larger in inner diameter than the first barrel portion, so that a second chamber defined by an axial end surface of the first barrel portion located opposite to the side of the combustion chamber and an inner circumferential surface of the second barrel portion is provided at an axial end of the holder assembly located opposite to the side of the combustion chamber, and
a portion that receives the connector connected to the terminal pin is defined by the second chamber.
4. The gas generator according to claim 1 , wherein
an outer circumferential surface of the first barrel portion is decreased in diameter toward the combustion chamber.
5. The gas generator according to claim 1 , further comprising:
a filter arranged in inside of the housing main body; and
a partition member arranged in the inside of the housing main body to divide, in the axial direction of the housing main body, a space in the inside of the housing main body into a filter chamber where the filter is arranged and the combustion chamber, wherein
the partition member is fixed to the housing main body by being welded.
6. The gas generator according to claim 1 , further comprising a coil spring interposed between the holder assembly and the gas generating agent, the coil spring fixing the gas generating agent in inside of the housing main body by biasing the gas generating agent toward a side opposite to a side where the holder assembly is located while the gas generating agent is spaced apart from the ignition portion, wherein
the ignition portion includes a cup body cleaved by ignition of the ignition agent at time of activation of the igniter, and
the coil spring is arranged substantially coaxially with the ignition portion to surround the ignition portion without interposition of another member between the coil spring and the ignition portion, so as to restrict a degree of opening of the cup body at time of cleavage of the cup body.
7. The gas generator according to claim 6 , wherein
the ignition portion has a substantially columnar outer geometry,
the coil spring includes
a circular cylindrical portion located on a side of the holder assembly and having a constant inner diameter, and
an increased-diameter portion that extends from an end of the circular cylindrical portion on a side of the gas generating agent toward the gas generating agent and increases in inner diameter toward the gas generating agent, and
a portion of the coil spring that surrounds the igniter is implemented by the circular cylindrical portion.
8. The gas generator according to claim 7 , wherein
a condition of 0<C≤(R1−R2)×(L2/L1)/2 is satisfied, where R1 represents an inner diameter of a portion of the housing main body where the gas generating agent is accommodated, R2 represents an outer diameter of the ignition portion, L1 represents a distance along the axial direction of the housing main body from a portion of the ignition portion where the ignition agent is accommodated to the gas generating agent, L2 represents a distance along the axial direction of the housing main body from the portion of the ignition portion where the ignition agent is accommodated to a boundary between the circular cylindrical portion and the increased-diameter portion, and C represents a clearance between the ignition portion and the circular cylindrical portion.
9. The gas generator according to claim 8 , wherein
the clearance is not larger than 1.0 mm.
10. The gas generator according to claim 6 , wherein
a portion of the coil spring that surrounds the ignition portion is in contact with the ignition portion.