Hybrid inflator

• US 5,257,819 A
• Filed: 12/02/1992
• Issued: 11/02/1993
• Est. Priority Date: 11/27/1990
• Status: Expired due to Term

• Current Assignee: Arc Automotive Incorporated (The Jordan Co. LP)
• Original Assignee: Bendix-Atlantic Inflator Company
• Inventors: Rose, James M., Brown, Roy, Woods, Charles D., Bishop, Robert J., Renfroe, Donald W., Frantom, Richard L., Ocker, Klaus F., Bazel, Teresa L., Kremer, Robert M.
• Primary Examiner(s): FERRITER, KARIN L
• Application Number:
  US07/985,511
• Time in Patent Office: 335 Days
• Field of Search: 222/5, 280/737, 280/736, 280/741, 280/728, 137/68.2, 102/530, 102/531, 422/164, 422/165, 422/166
• US Class Current: 280/737
• CPC Class Codes: B60R 21/272 with means for increasing the pressure of the gas just before or during liberation, e.g. hybrid inflators
• CPC Class Codes: F42B 3/04 for producing gas under pressure generators of inflation fluid especially adapted for vehicle air bags B60R21/26
• CPC Class Codes: Y10T 137/1647 Explosive actuation

Abstract

An inflator (110) including: a pressure means (12, 14, 16, 20) for storing a quantity of stored inflation gas under pressure. The pressure means including a first burst disk (46) in communication with the stored inflation gas and preventing egress of the gas from the chamber and a hollow sliding piston (172) having at one end thereof cutting edges (174) for puncturing the first burst disk (46). A shear disk (180) having a stationary outer portion (187) and a central portion or second disk (186), central portion is secured to one end of the piston (172) opposite the cutting edges (174). The central portion is capable of separating from the outer portion and moving with the piston (172). A quantity of propellant material (218) is provided near the second burst disk (80) to produce gaseous combustion products when burned. The piston is propelled into the first burst disk (46) after the central portion (186) of the shear disk separates from the outer portion in response to the build up of pressure generated due to the burning of a propellant (218), thereby permitting the egress of the stored inflation gas. The central portion (186) or second burst disk is ruptured by the continued build up of pressure due to the burning propellant material whereupon after the rupturing of the second burst disk the heated products of combustion resulting from the burning propellant material flow through the sliding piston (172).

Claims

1. An inflator comprising:

a pressure means for storing a quantity of stored inflation gas under pressure, the pressure means comprising a first burst disk in communication with the stored inflation gas and preventing egress of the gas from the chamber;

a hollow sliding piston having an opening and including at one end thereof first means for puncturing the first burst disk;

a shear disk having a stationary outer portion and a central or inner portion, the central portion secured to one end of the piston opposite the first means and the central portion capable of separating from the outer portion and moving with the piston, the central portion functioning as a second burst disk, the stationary outer section having a burst strength which is less than a burst strength of the central or inner portion;

a propellant material provided near the second burst disk, said propellant producing gaseous combustion products when burned;

the piston being propelled into the first burst disk after the central portion of the shear disk separates from the outer portion in response to the build up of pressure generated due to the burning of a propellant, thereby permitting the egress of the stored inflation gas, the central portion or second burst disk being ruptured by the continued build up of pressure due to the burning propellant material whereupon after the rupturing of the second burst disk the heated products of combustion resulting from the burning propellant material flow through the sliding piston to increase the temperature of the stored inflation gas prior to its exit from the inflator.

2. The inflator as defined in claim 1 wherein the pressure means comprises a cylindrical sleeve, a first end cap secured at one end thereof and a second end cap secured at another end thereof, the second end cap being of generally cylindrical shape and including a narrowed portion extending into the sleeve, the narrowed portion defining a first opening, the first burst disk being secured to the narrow portion to close the first opening, the second end cap further including at least one orifice opening through which gases escape upon the puncturing of the first burst disk.

3. The inflator as defined in claim 1 wherein the first end cap supports a pressure sensor positioned interior to the pressure means.

4. The inflator as defined in claim 1 wherein a propellant housing is positioned within and generally spaced from the interior of the second end cap, the housing including a second opening facing the first burst disk,

a hollow sleeve member is secured to the housing and extends through the second opening, the sliding piston is received within the sleeve member and wherein the outer portion of the shear disk is secured to the sleeve member.

5. The inflator as defined in claim 4 wherein the shear disk includes a stress riser between the outer portion and central portion, the stress riser providing a weakened region along which the central portion separates from the outer portion.

6. The inflator as defined in claim 5 wherein the stress riser comprises a circular groove.

7. The inflator as defined in claim 4 wherein the shear disk includes a second stress riser located within the central portion defining a weakened region therein, the central portion or second burst disk opening along this region at a determinable pressure to allow the products of combustion of the burning propellant to mix with the stored inflation gas.

8. The inflator as defined in claim 7 wherein the second stress riser comprises two intersecting grooves.

9. The inflator as defined in claim 1 wherein the piston and sleeve member cooperate to provide an interference fit therebetween when the piston has moved to its burst disk piercing position, thereby preventing the piston from being moved backwardly by the escaping inflation gas.

10. The inflator as defined in claim 9 wherein the piston includes a groove capable of being trapped by the sleeve member after the piston has moved forwardly thereby further locking the piston is its forward position.

11. The inflator as defined in claim 1 wherein the propellant material is secured within the propellant housing spaced from the sliding piston, an initiator means responsive to a control signal indicative of a crash situation, for generating heat to cause the propellant to burn, bias means interposing the initiator means and propellant material for preloading the propellant material to prevent movement of same.

12. The inflator as defined in claim 11 wherein the bias means comprises a screen in contact with the propellant material the screen functions as a means of uniformly distributing the heat generated by the initiator means to the propellant.

13. The inflator as defined in claim 12 wherein the bias means further includes a resilient material which preloads the screen onto the propellant material.

14. The inflator as defined in claim 1 wherein a diffuser is positioned about the inflator to distribute gas of inflation to an air bag, such air bag mounted about the diffuser.

15. The inflator as defined in claim 11 wherein the initiator means includes an initiator housing secured to the propellant housing and a squib or initiator for initiating the burning of the propellant material, and ignition enhancing means positioned between the squib and the propellant material for increasing the heat supplied to the propellant material.

16. The inflator as defined in claim 13 wherein the resilient material is silicone.

17. An inflator comprising:

pressure means for storing a quantity of inflation gas under pressure comprising a first burst disk for preventing egress of the inflation gas;

a sliding piston including at one end thereof first means for puncturing the first burst disk;

a shear disk having a stationary outer portion and a central or inner portion, the central portion secured to one end of the piston opposite the first means and the central portion capable of separating from the outer portion and moving with the piston, the central portion functioning as a second burst disk, the stationary outer portion having a burst strength which is less than the central or inner portion;

propellant material for producing gaseous combustion products when burned;

the piston being propelled into the first burst disk after the central portion of the shear disk separates from the outer portion in response to the build up of pressure generated due to the burning of a propellant, thereby permitting the egress of the stored inflation gas from the pressure means, the central portion or second burst disk being ruptured by the continued build up of pressure due to the burning propellant material whereupon after the rupturing of the second burst disk the heated products of combustion resulting from the burning propellant material flow past the sliding piston into the pressure means to increase the temperature of the stored inflation gas prior to its exit from the inflator.

18. The inflator as defined in claim 17 wherein the sliding piston is hollow and the heated products of combustion flow through the sliding piston into the pressure means.