Hybrid inflator with staged inflation capability

• US 5,351,988 A
• Filed: 04/14/1992
• Issued: 10/04/1994
• Est. Priority Date: 11/27/1990
• Status: Expired due to Fees

• Current Assignee: Bendix-Atlantic Inflator Company, Alliedsignal Inc. (Honeywell International Inc.)
• Original Assignee: Alliedsignal Inc. (Honeywell International Inc.)
• Inventors: Ross, James, Bishop, Robert J., Renfroe, Donald W., Brown, Roy G., Frantom, Richard L., Ocker, Klaus F., Kremer, Robert M.
• Primary Examiner(s): FERRITER, KARIN L
• Application Number:
  US07/833,240
• Time in Patent Office: 903 Days
• Field of Search: 280/737, 280/735, 280/741, 280/728, 280/736, 222/5, 137/68.2, 102/530, 102/531, 422/164, 422/165, 422/166
• US Class Current: 280/737
• CPC Class Codes: B60R 2021/2633 with a plurality of inflation levels
• 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

Abstract

An inflator comprising: a pressure vessel (10) for storing a quantity of stored inflation gas under pressure. The pressure vessel comprising a first burst disk (46) and a seal disk (310) both for selectively sealing same. The inflator (10) including a gas release mechanism (52, 300) for permitting the controlled, staged release of the inflation gas at determinable inflation rates. The gas release mechanism includes: a first pyrotechnic device, positioned outside of the pressure vessel and spaced from the first burst disk (46), including a piston (72) moved into a disk piercing position to rupture the first burst disk (46) in response to the buildup of pressure caused burning of a first quantity of propellant material (218). The bursting of the first burst disk permits the inflation gas to initially flow out of the pressure vessel at a determinable cold inflation rate, the piston thereafter provides a conduit to communicate the products of combustion of the burning propellent to the pressure means so as to increase the temperature of the inflation gas therein and thereby increase the rate of egress of the gas. The inflator (10) also includes a second pyrotechnic mechanism (300), positioned outside of the pressure vessel and spaced from the seal disk (310), for providing, when activated, additional products of combustion arising from burning of a second quantity of propellent material, the products of combustion opening the seal disk (310) and thereafter entering the pressure vessel to heat the inflation gas therein and thereby elevate the rate of egress of the inflation gas above the rate achievable by the first pyrotechnic device.

Claims

1. An inflator (10) comprising:

a pressure means (12, 14, 16,

     20) for storing a quantity of inflation gas under pressure, the pressure means comprising a first housing having a first part extending into the pressure means and a second part in contact with the pressure means for sealing one end of the pressure means, the first part including an opening closed by a first burst disk (46) and a second housing (302) having a first part extending into the pressure means and a second part in contact with the pressure means for closing a second end of the pressure means, the first part of the second housing including at least one additional opening closed by a seal disk (310);

gas release means (52,

     300) for permitting the controlled, staged release of the inflation gas at determinable inflation rates, such gas release means including;

first pyrotechnic means, for generating products of combustion for heating the stored gas, positioned outside of the pressure means and spaced from the first burst disk (46), including a piston (72) moved into a disk piercing position to rupture the first burst disk (46) in response to the buildup of pressure caused burning of a first quantity of propellant material (218), the bursting of the first burst disk permitting the inflation gas to initially flow out of the pressure means at a determinable cold inflation rate, the piston thereafter providing a conduit to communicate the products of combustion of the burning propellent to the pressure means so as to increase the temperature of the inflation gas therein and thereby increase the rate of egress of the gas;

second pyrotechnic means (300), positioned in the second housing, positioned outside of the pressure means and spaced from the seal disk (310), for providing, when activated, additional products of combustion arising from burning of a second quantity of propellent material, the products of combustion opening the seal disk (310) and thereafter entering the pressure means to heat the inflation gas therein and thereby elevate the rate of egress of the inflation gas above the rate achievable by the first pyrotechnic means.

2. The inflator as defined in claim 1 wherein the first pyrotechnic means includes

a hollow sliding piston (72) having an opening and including at one end thereof first means (74) for puncturing the first burst disk (46);

a shear disk (80) having a stationary outer portion (87) and a central or inner portion (86), the central portion secured to one end of the piston (72) opposite the first means (74) and the central portion capable of separating from the outer portion and moving with the piston (72), the central portion functioning as a second burst disk, a portion of the shear disk radially outward of the portion of the disk connected to the piston is weaker than the central portion;

the first quantity of propellant material (218) provided near the second burst disk (80), said propellant material producing gaseous combustion products when burned;

the piston being propelled into the first burst disk (46) after the central portion (86) 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 material (218), thereby permitting the egress of the stored inflation gas, the central portion (86) 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 (72) to increase the temperature of the stored inflation gas prior to its exit from the inflator.

3. The inflator (10) as defined in claim 1 wherein the volume of the pressure means, the pressure at which pressurized inflation gas is stored therein, the first quantity of propellent material and the heat generated thereby are selected such that the rate of inflation gas flow communicated to a coacting air bag is sufficient to inflate the air bag to a first level during a vehicular accident above a threshold crash level and below a second crash level.

4. The inflator (10) as defined in claim 3 wherein the second pyrotechnic means is activated after or simultaneously to the activation of the first pyrotechnic means, wherein the quantity of second propellent material and the heat generated thereby cause the air bag to be inflated at a rate greater than that achieved by activation of the first pyrotechnic means during a vehicular accident of between the second crash level and a third crash level.

5. The inflator as defined in claim 4 wherein the threshold and second accident levels are each respectively in a range from approximately 10-18 and 18-35 miles hour.

6. The inflator (10) as defined in claim 3 wherein the threshold level corresponds to one of vehicle deceleration or vehicle crash velocity at which most injury crashes occur.

7. The inflator as defined in claim 1 wherein a plurality of openings (312) are at one end of the second housing interior of the pressure means, and wherein the seal disk (310) is positioned upon an exterior wall of the second housing to seal the plurality of opening, the seal disk being opened, to expose the plurality of openings, to the products of combustion produced upon activation of the second pyrotechnic means.

8. The inflator as defined in claim 2 wherein the gas release means includes means for activating the first and second pyrotechnic means with a time delay between such activations in proportion to the severity of a crash.