Patent ID: 8367233

Claim:
A battery pack thermal management system, comprising: a battery pack enclosure configured to hold a plurality of batteries, wherein said battery pack enclosure is comprised of a high temperature material; and an enclosure failure port assembly integrated into a wall of said battery pack enclosure, wherein said wall of said battery pack enclosure has a first wall thickness, wherein said enclosure failure port assembly remains closed during normal operation of said battery pack, and wherein said enclosure failure port assembly opens during a battery pack thermal runaway event and provides a flow path for exhausting hot gas from within said battery pack enclosure, wherein said enclosure failure port assembly directs said flow path at an angle away from a normal of said wall of said battery pack enclosure, and wherein said enclosure failure port assembly further comprises: a substantially circular region of said wall, said substantially circular region having a second wall thickness that is thinner than said first wall thickness; a transition region interposed between said substantially circular region and a surrounding portion of said wall that surrounds said substantially circular region, wherein a first portion of said transition region encircling a first portion of said substantially circular region has a third wall thickness that is thicker than said second wall thickness and thinner than said first wall thickness, wherein a second portion of said transition region encircling a second portion of said substantially circular region has a fourth wall thickness that is thinner than said second wall thickness and thinner than said first wall thickness, wherein said second portion of said transition region fails before said first portion of said transition region during said battery pack thermal runaway event and allows hot gas from within said battery pack enclosure to exhaust through said substantially circular region at an angle away from said normal of said wall of said battery pack enclosure.