# US 8,656,838 B1 · Secondary chamber combustion control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,656,838 B1 - Document ID: US8656838B1 - Status: Granted - Kind: B1 - Application number: 13/247,221 - Filed: 2011-09-28 - Granted: 2014-02-25 - Earliest claimed: 2010-09-28 - Assignees: TK Holdings Inc. - Applicants: Brian A. Mayville - Inventors: Brian A. Mayville - Web page: https://patentgrep.com/patent/US8656838B1 ## CPC - B60R 21/264: using instantaneous generation of gas, e.g. pyrotechnic (B60R21/268 takes precedence) - B60R 21/263: using a variable source, e.g. plural stage or controlled output (hybrid inflators B60R21/272) - B60R 21/2644: {using only solid reacting substances, e.g. pellets, powder} - B60R 21/274: characterised by means to rupture or open the fluid source - C06D 5/00: Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets (explosive compositions containing an oxidizer, fuels for rocket engines intended for reaction with an oxidant other than air C06B) - B60R 2021/2633: {with a plurality of inflation levels} - B60R 2021/2642: {comprising a plurality of combustion chambers or sub-chambers} - B60R 2021/2648: {comprising a plurality of combustion chambers or sub-chambers} - B60R: VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR - C06D: MEANS FOR GENERATING SMOKE OR MIST; GAS-ATTACK COMPOSITIONS; GENERATION OF GAS FOR BLASTING OR PROPULSION (CHEMICAL PART) (fuels C10) ## Abstract A gas generating system includes a first chamber activatable to provide a first quantity of gas and a second chamber activatable independently of the first chamber to provide a second quantity of gas. A single opening enables fluid communication between the second chamber and the first chamber. A barrier seals the opening to prevent fluid communication between the first and second chambers prior to activation of the second chamber. ## Claims ### Claim 1 A gas generating system comprising: a housing; a first chamber within the housing and structured to be activatable to provide a first quantity of gas; a shell positioned within the first chamber and including a flat base and a wall extending from a periphery of the base to define a second chamber structured to be activatable independently of the first chamber to provide a second quantity of gas; a plurality of openings formed along the base and enabling fluid communication between the second chamber and the first chamber; and a barrier sealing the openings to prevent fluid communication between the first and second chambers prior to activation of the second chamber. ### Claim 2 (depends on 1) The gas generating system of claim 1 wherein the barrier comprises a shim attached to a surface of the shell. ### Claim 3 (depends on 1) The gas generating system of claim 1 wherein the barrier is structured to overlap the plurality of openings and is secured to the flat portion of the surface at an attachment structured to form a gas-tight seal between the barrier and the surface, the attachment being positioned with respect to the plurality of openings such that, for each opening of the plurality of openings, a spacing of at least a predetermined value (d) is provided between the opening and the attachment. ### Claim 4 (depends on 1) The gas generating system of claim 1 wherein the plurality of openings are sized such that a pressure within a range having a lower limit of about 20 MPa is maintained in the second chamber after failure of the barrier for at least a predetermined time period after a start of combustion of a gas generant material positioned in the second chamber. ### Claim 5 (depends on 4) The gas generating system of claim 4 wherein the pressure range has an upper limit of between 50 MPa and 90 MPa. ### Claim 6 (depends on 5) The gas generating system of claim 5 wherein the pressure range has an upper limit of 60 MPa. ### Claim 7 (depends on 4) The gas generating system of claim 4 wherein the plurality of openings are sized such that a pressure within the range is maintained in the second chamber after failure of the barrier for at least the predetermined time period after failure of the barrier, when a pressure acting on an exterior of the second chamber is at or about ambient atmospheric pressure. ### Claim 8 (depends on 4) The gas generating system of claim 4 wherein the barrier is structured to fail when a pressure differential between an interior of the second chamber and an exterior of the second chamber reaches a value of about 20 MPa. ### Claim 9 (depends on 1) An airbag system including a gas generating system in accordance with claim 1. ### Claim 10 (depends on 1) A vehicle occupant protection system including a gas generating system in accordance with claim 1. ### Claim 11 A gas generating system comprising: a first chamber activatable to provide a first quantity of gas; a second chamber activatable independently of the first chamber to provide a second quantity of gas; a quantity of gas generant material positioned in the second chamber; a plurality of openings formed along a flat portion of a surface defining a portion of the second chamber, the openings enabling fluid communication between the second chamber and the first chamber; and a barrier sealing the openings to prevent fluid communication between the first and second chambers prior to activation of the second chamber, wherein the plurality of openings are sized so as to enable a pressure within a range having a lower limit of about 20 MPa to be maintained in the second chamber after failure of the barrier for at least a predetermined time period after a start of combustion of the gas generant material. ### Claim 12 (depends on 11) The gas generating system of claim 11 wherein the pressure range has an upper limit of between 50 MPa and 90 MPa. ### Claim 13 (depends on 11) The gas generating system of claim 11 wherein the pressure range has an upper limit of 60 MPa.