Gas generator for multi-stage air bag and air bag device

A multistage air bag apparatus, comprising:

• an air bag gas generator, including,
• a housing including a diffuser shell having a plurality of gas discharge ports formed in a circumferential outer wall thereof, and a closure shell attached to the diffuser shell;
• a first combustion chamber and a second combustion chamber provided inside said housing, each of the first combustion chamber and the second combustion chamber accommodating gas generating agents which generate combustion gas that inflates the air bag,
• a first ignition unit for directly igniting only the gas generating agent accommodated in the first combustion chamber;
• a second ignition unit for directly igniting only the gas generating agent accommodated in the second combustion chamber;
• an inner cylinder for accommodating the first ignition unit therein and having at least an open end opposing the diffuser shell;
• a lid made of an element independent from said inner cylinder and provided between the open end and the diffuser shell such that a first surface of said lid opposes the diffuser shell and a second surface thereof covers the open end, said lid being substantially flat and having no opening at least in a portion thereof where the lid covers the open end;
• and
• a control unit including a first outputting portion and a second outputting portion for outputting activation signals to said first ignition unit and said second ignition unit through a first lead wire and a second lead wire, respectively, the first lead wire and the second lead wire including, at one end thereof, a first connector and a second connector provided with a first defining unit for selectively and electrically communicating the first outputting portion with the first connector, and the second outputting portion with the second connector,
• wherein said inner cylinder is provided eccentrically with respect to a center axis of said housing, and said first ignition unit and said second ignition unit are disposed in said housing eccentrically with respect to the center axis of said housing.

A multistage gas generator for an air bag, comprising:

• a housing including a diffuser shell having a plurality of gas discharge ports formed in a circumferential outer wall thereof, and a closure shell attached to the diffuser shell;
• a first combustion chamber and a second combustion chamber provided inside the housing, each of the first combustion chamber and the second combustion chamber accommodating gas generating agents which generate combustion gas that inflates the air bag;
• a first ignition unit attached to the housing for directly igniting only a gas generating agent accommodated in the first combustion chamber;
• a second ignition unit attached to the housing for directly igniting only a gas generating agent accommodated in the second combustion chamber;
• an inner cylinder for accommodating the first ignition unit therein and having at least an open end opposing the diffuser shell;
• a single retainer provided with a bent portion bent in an axial direction of said housing, and disposed inside the first combustion chamber such that the bent portion is in engagement with an outer circumferential surface of said inner cylinder;
• and
• a cylindrical filter unit for at least one of purifying and cooling an activation gas and including an inclining end surface formed at an end portion thereof to be narrower in an axial extending direction such that an interior angle with respect to an inner peripheral surface is an acute angle, and said housing is provided with a supporting member that opposes and contacts the inclining end surface,
• wherein said inner cylinder is provided eccentrically with respect to a center axis of said housing, and the first ignition unit and the second ignition unit are disposed in said housing eccentrically with respect to the center axis of said housing, and
• wherein said cylindrical filter unit is provided with an inclining end surface at both ends thereof.

A method of manufacturing a multistage gas generator for an air bag, comprising:

• providing a cylindrical housing including a diffuser shell provided with a plurality of gas discharge ports formed in a circumferential outer wall thereof, and a closure shell;
• providing, within the housing, a first combustion chamber and a second combustion chamber, each of the first combustion chamber and the second combustion chamber accommodating gas generating agents which generate combustion gas that inflates the air bag;
• providing, within the housing, a coolant for at least one of cooling and filtering combustion gas generated upon combustion of the gas generating agents;
• providing first ignition means for directly igniting and burning only the gas generating agent accommodated in the first combustion chamber;
• providing second ignition means for directly igniting and burning only the gas generating agent accommodated in the second combustion chamber;
• providing, within the housing, a cylindrical member for accommodating the first ignition means therein, and having at least an open end opposing the diffuser shell;
• providing, within the housing, a single retainer having a bent portion bent in an axial direction of said housing, and disposed inside the first combustion chamber such that the bent portion is in engagement with an outer circumferential surface of said cylindrical member;
• providing a lid, made of an element independent from said inner cylinder, between the open end and the diffuser shell such that a first surface of said lid opposes the diffuser shell and a second surface thereof covers the open end, said lid being substantially flat and having no opening at least in a portion thereof where the lid covers the open end;
• and
• attaching the closure shell to the diffuser shell by friction welding.

A multistage gas generator for an air bag, comprising:

• a cylindrical housing including a diffuser shell provided with a plurality of gas discharge ports and a closure shell, said cylindrical housing containing a first combustion chamber therein;
• an inner shell defining a second combustion chamber therein, said inner shell being provided inside the housing such that a center axis of said inner shell is eccentric with respect to a center axis of said housing;
• a first gas generating agent provided inside the first combustion chamber and in direct contact with said inner shell;
• a second gas generating agent, provided inside the second combustion chamber, for generating combustion gas that inflates the air bag;
• a single coolant that cools combustion gas generated by combustion of at least one of said first gas generating agent and said second gas generating agent, said single coolant being provided within said housing such that an inner circumferential surface defines a first combustion chamber;
• a first ignition unit for directly igniting and burning only the first gas generating agent;
• and
• a second ignition unit for directly igniting and burning only the second gas generating agent.

A multistage gas generator for an air bag, comprising:

• a cylindrical housing including a diffuser shell, provided with a plurality of gas discharge ports, and a closure shell, said cylindrical housing defining a first combustion chamber therein;
• an inner shell defining a second combustion chamber therein, said inner shell being provided inside said housing such that a center axis of said inner shell is eccentric with respect to a center axis of said housing;
• a first gas generating agent provided inside the first combustion chamber;
• a second gas generating agent, provided inside the second combustion chamber, for generating combustion gas that inflates the air bag;
• a first igniter provided inside the first combustion chamber;
• a second igniter provided inside the second combustion chamber;
• a transfer charge provided inside the first combustion chamber to be ignited by said first igniter and for igniting said first gas generating agent, said transfer charge generating a combustion product;
• an inner cylinder provided within the first combustion chamber for accommodating said transfer charge therein, a center axis of said inner cylinder being eccentric with respect to the center axis of said housing and having a plurality of flame transferring holes provided in equal intervals for evenly distributing the combustion product, generated in said inner cylinder, into the first combustion chamber except in directions along an imaginary line that intersects with a center axis of the inner cylinder and the center axis of said housing for evenly igniting the first gas generating agent.

A multistage gas generator for an air bag, comprising:

• a housing including a diffuser shell having a plurality of gas discharge ports formed in a circumferential outer wall thereof, and a closure shell attached to the diffuser shell;
• a first combustion chamber and a second combustion chamber provided inside the housing, each of the first combustion chamber and the second combustion chamber accommodating gas generating agents which generate combustion gas that inflates the air bag;
• first ignition means attached to the housing for directly igniting only the gas generating agent accommodated in the first combustion chamber;
• second ignition means attached to the housing for directly igniting only the gas generating agent accommodated in the second combustion chamber;
• an inner cylinder including a circumferential wall and accommodating the second ignition means therein, the circumferential wall having an opening portion;
• and
• a shielding plate disposed outside the inner cylinder and opposing and spaced apart from the opening portion, the shielding plate preventing a combustion flame, generated in the combustion chamber provided outside the inner cylinder, from coming into direct contact with the opening portion.