Airbag inflator for vehicle occupant restraint apparatus
First Claim
Patent Images
1. An airbag inflator comprising:
- a casing having a vent for fluid communication with an airbag;
a cylinder provided in the casing;
a piston slidably received in the cylinder, the piston including;
a piston head defining, to a rearward side, a reservoir containing a liquid propellant, and, to a forward side, a combustion chamber in fluid communication with the housing vent, andinjection ports extending through the piston head between the reservoir and the combustion chamber;
a seal ring slidably received in the cylinder and having a surface area exposed to the reservoir, the seal ring normally blocking the injection ports; and
an inflation initiator operable, in response to a vehicle collision, to pressurize the reservoir and to drive the seal ring forwardly to unblock the injection ports, such that liquid propellant may flow into the combustion chamber for ignition and generation of combustion gases that flow through the vent to inflate the airbag.
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Abstract
To achieve a reduced inflation rate of an airbag in a vehicle occupant restraint apparatus, an airbag inflator is provided with a seal ring acting, in response to initial pressurization by a pyrotechnic initiator, to open injection ports, such that liquid propellant may be regeneratively pumped by a piston from a reservoir into a combustion chamber for combustion. The resulting combustion gases flow through a series of swirl chambers to increase residence time and through a plenum chamber where the combustion gases are cooled. The combustion gases exit the plenum chamber as an airbag inflation gas.
46 Citations
39 Claims
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1. An airbag inflator comprising:
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a casing having a vent for fluid communication with an airbag; a cylinder provided in the casing; a piston slidably received in the cylinder, the piston including; a piston head defining, to a rearward side, a reservoir containing a liquid propellant, and, to a forward side, a combustion chamber in fluid communication with the housing vent, and injection ports extending through the piston head between the reservoir and the combustion chamber; a seal ring slidably received in the cylinder and having a surface area exposed to the reservoir, the seal ring normally blocking the injection ports; and an inflation initiator operable, in response to a vehicle collision, to pressurize the reservoir and to drive the seal ring forwardly to unblock the injection ports, such that liquid propellant may flow into the combustion chamber for ignition and generation of combustion gases that flow through the vent to inflate the airbag. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An airbag inflator comprising:
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a casing; a cylinder provided in the casing; a piston slidably received in the cylinder, the piston including; a piston head defining, to a rearward side, a reservoir containing a liquid propellant, and, to a forward side, a combustion chamber, and normally blocked injection ports extending through the piston head between the reservoir and the combustion chamber; a first swirl chamber provided in the casing, the first swirl chamber including entry swirl ports in fluid communication with the combustion chamber and exit swirl ports; a second swirl chamber surrounding the first swirl chamber and in fluid communication with the exit swirl ports; inflation ports provided in a wall of the casing for fluid communication with an airbag; and an inflation initiator, operable, in response to a vehicle collision, to pressurize the reservoir and unblock the injection ports, such that liquid propellant may flow into the combustion chamber for ignition and generation of combustion gases that flow through the entry swirl ports into the first swirl chamber, through the exit swirl ports into the secondary swirl chamber, and through the inflation ports enroute to the airbag. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. An airbag inflator comprising:
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a casing having inflation ports; a cylinder provided in the casing; a piston slidably received in the cylinder, the piston including; a piston head defining, to a rearward side, a reservoir containing a liquid propellant, and to a forward side, a combustion chamber; normally blocked injection ports extending through the piston head between the reservoir and the combustion chamber, and a piston rod joined with the piston head and extending rearwardly through a casing endwall, the piston rod including a cavity and a normally blocked passage leading from the cavity into the combustion chamber; and an inflation inflator provided in the piston rod cavity and operable, in response to a vehicle collision, to pressurize the combustion chamber through the passage, the pressurized combustion chamber producing a fluid pressure in the reservoir effective to unblock the ejection ports and then to pump liquid propellant through the ejection ports into the combustion chamber for ignition and generation of combustion gases that flow through the inflation ports to inflate an airbag. - View Dependent Claims (27, 28, 29)
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30. An passive occupant restraint apparatus comprising, in combination:
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a housing configured for installation in a motor vehicle, the housing including first and second compartments; an airbag stored in the first housing compartment In folded configuration; and an inflator disposed in the second housing compartment in fluid flow communication with the airbag in the first housing compartment, the inflator including; a casing, a cylinder provided in the casing, a piston slidably received in the cylinder, the piston including a piston head defining, to the rearward side, a reservoir containing a liquid propellant, and, to a forward side, a combustion chamber, and a piston rod joined with the piston head and extending rearwardly through an endwall of the casing, the piston rod being cylindrical in shape to provide a cavity, and a passage extending through the piston head between the piston rod cavity and the combustion chamber, injection ports extending through the piston head between the reservoir and the combustion chamber, a collision sensor, and an initiator including a solid propellant stored in the piston rod cavity and an electrically detonatable squib sealed in an opening into the cavity through an open end of the piston rod beyond the endwall, the squib wired to the collision sensor, whereby detonation of the squib by the collision sensor in response to a vehicle accident ignites the solid propellant to produce combustion gases flowing through the passage to pressurize the combustion chamber, pressurization of the combustion chamber produces a fluid pressure in the reservoir effective to pump liquid propellant from the reservoir into the combustion chamber for ignition and generation of combustion gases that flow through inflation ports in the casing to inflate the airbag. - View Dependent Claims (31, 32, 33, 34, 35)
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36. An airbag inflator comprising:
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a casing having inflation ports; a combustion chamber in the casing for receiving a propellant; at least one swirl chamber in the casing and including swirl ports; and an initiator in the casing for igniting the propellant in the combustion chamber to produce combustion gases that flow through the swirl ports into the swirl chamber and through the swirl chamber in a swirling, circular manner to increase residence time while enroute to the inflation ports where the combustion gases exit the casing as an inflation gas to deploy an airbag. - View Dependent Claims (37, 38, 39)
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Specification