While this may sound surprising at first, it actually is a very good idea. That’s because it protects first responders from electric shock after an electric vehicle accident. The small Bosch explosions blow sections of wiring apart. Wouldn’t it be lovely if we could do the same with thermal runaway?
A Semiconductor Triggers a Series of Small Bosch Explosions
Bosch is following the old inertia switch routine. Controls already provide safety cutouts in gas-powered vehicles, and some gasoline ones too. However there is no undo switch in the case of these pyrofuses according to Car and Driver magazine.
A semiconductor chip activates 4 pyrofuses at various points when a vehicle’s sensors detect a collision impact. Together, these comprise a ‘pyrotechnical safety switch system’ that physically blows apart sections of wiring. However, rest assured the small Bosch explosions are only large enough to isolate the battery.
How the Miniature Explosions Sever the Wires
Four pyrofuses sever the wires at selected points using wedges.. These cut off the electricity flow, enabling first responders to touch metal parts safely. However, the electrical energy remains in the battery itself. Therefore there is still a real possibility of thermal runaway if the battery cells are damaged.
The semiconductor chips are application-specific integrated circuits (ASICs). Each ASIC has millions of transistors and will respond “within a fraction of a second.” Bosch has used the technology in airbags for years. It says it has been successful in the field “a million times over.” Their CG912 pyrofuse system causing small Bosch explosions after impacts appeared at the Electronica 2018 trade show.
Bosch has not announced which electric vehicles benefit from the technology. We think those products should have pyrofuse labels. That’s because response time may be of the essence when saving lives after accidents.
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Preview Image: Semiconductor Technology for Safety of Hybrid and Electric Vehicles
