Gas generator for an air bag and air bag system

• US 6,679,521 B2
• Filed: 12/13/2001
• Issued: 01/20/2004
• Est. Priority Date: 06/26/1998
• Status: Expired due to Term

• Current Assignee: Daicel Chemical Industries Limited (Daicel Corporation)
• Original Assignee: Daicel Chemical Industries Limited (Daicel Corporation)
• Inventors: Miyaji, Katsuhito, Yamazaki, Masayuki
• Primary Examiner(s): Dickson, Paul N.
• Assistant Examiner(s): DRAPER, DEANN L
• Application Number:
  US10/013,865
• Publication Number:
  US 20020070540A1
• Time in Patent Office: 768 Days
• Field of Search: 280/741, 280/728.1, 280/736, 280/743.1
• US Class Current: 280/741
• CPC Class Codes: B60R 2021/2607 characterised by heating or heat insulating means, e.g. for use under extreme temperatures
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

A gas generator for an air bag, in which conduction of heat generated by combustion of a gas generating agent is restricted to effectively reduce or inhibit a temperature increase of a diffuser side on an outer shell container, is provided and thus, reduces the maximum surface temperature of the diffuser. The gas generator includes a housing which has a diffuser shell with at least one gas discharge port and a closure shell for forming an accommodating space together with the diffuser shell and the gas generating agent, installed in the housing, ignited and burnt by an igniting unit to generate a combustion gas, wherein the gas generator further includes a heat transfer restricting member for making a conduction of heat generated by a combustion of the gas generating agent to the diffuser shell side smaller than that to the closure shell side.

Claims

1. A gas generator for an air bag, comprising:

a housing having a top plate, a bottom plate, and a circumferential outer wall connecting the top plate and the bottom plate;

a tubular member provided within said housing, said tubular member storing ignition means therein and being fixed to the bottom plate;

coolant means, provided within said housing and outside the tubular member, for cooling combustion gas generated by gas generating means provided inside said housing; and

a contact preventing member, provided in a first space defined by an upper end surface of said coolant means and an inner surface of said top plate opposing the upper end surface, for preventing the upper end surface of said coolant means from making direct contact with the top plate to restrict heat conduction from said coolant means to the top plate after activation of the gas generator, said contact preventing member having a circular portion provided with a bent portion that engages with an outer peripheral surface of the tubular member.

2. The gas generator of claim 1, wherein said contact preventing member prevents combustion gas from by-passing between the upper end surface of said coolant means and a lower portion of said contact preventing member.

3. The gas generator according to claim 1, wherein a second space is defined by an outer peripheral portion of said coolant means and an inner surface of said circumferential outer wall.

4. A method of restricting an increase in temperature of a housing of a gas generator after activation thereof, the housing including a top plate, a bottom plate, and a circumferential outer wall connecting the top plate and the bottom plate, comprising:

providing a tubular member within the housing for storing an ignition unit therein;

providing a coolant unit within the housing and outside the tubular member for cooling combustion gas generated by gas generating unit provided inside the housing;

providing a first space defined by an upper end surface of the coolant unit and an inner surface of the top plate opposing the upper peripheral portion;

providing a contact preventing member inside the first space to prevent the upper end surface of the coolant unit from making direct contact with the top plate such that heat conduction from the coolant unit to the top plate after activation of the gas generator is restricted;

providing the contact preventing member with a circular portion having a bent portion; and

engaging the bent portion with an outer peripheral surface of the tubular member.

5. The method of claim 4, further comprising:

preventing the combustion gas from by-passing between the upper end surface of the coolant unit and a bottom surface of the contact preventing member.

6. The method of claim 4, further comprising;

providing a second space defined by an outer peripheral portion of the coolant unit and an inner surface of the circumferential outer wall.

7. A gas generator for an air bag, comprising:

a housing having a top plate, a bottom plate to which an ignition device is attached, and a circumferential outer wall connecting the top plate and the bottom plate;

a coolant unit provided within said housing and in contact with an inner surface of the bottom plate;

a tubular member provided inside said housing and concentrically with a central axis of said housing; and

a space forming member in contact with said tubular member provided inside an empty space defined by an inner surface of the top plate and an upper end surface of said coolant unit, an outer edge portion of the space forming member being slanted with respect to the inner surface of the top plate and the upper end surface of the coolant unit.

9. A gas generator according to claim 7, wherein said tubular member is provided inside said housing such that a longitudinal axis of said housing coincides with a longitudinal axis of said tubular member, and an end portion of said tubular member that faces the inner surface of the top plate is closed.

8. A gas generator for an air bag, comprising:

a housing having a top plate, a bottom plate, and a circumferential outer wall connecting the top plate and the bottom plate;

a coolant unit provided within said housing;

a tubular member provided inside said housing; and

a contact preventing member provided inside an empty space defined by an inner surface of the top plate and an upper end surface of said coolant unit and in contact with said tubular member, an upper surface of said contact preventing member being spaced apart from the inner surface of the top plate.

10. A gas generator according to claim 8, wherein said tubular member is provided inside said housing such that a longitudinal axis of said housing coincides with a longitudinal axis of said tubular member, and an end portion of said tubular member that faces the inner surface of the top plate is closed.