| Nissan is the latest OEM to develop
a pop-up bonnet. The feature debuts on the new Skyline coupe, which launches
in Japan in the autumn.
Pop-up bonnets mitigate pedestrian head impact injuries by creating space
above the engine and other hard surfaces. Powertrain packaging and aerodynamics
are in direct conflict with this requirement.
“We’ll fit this technology to vehicles that require low bonnet
styling,” said Nissan. “We chose a pop-up bonnet instead of
bonnet airbags because the entire bonnet works as an energy absorber.”
The system uses three accelerometers mounted in the front bumper to detect
impacts. Above 20km/h, an ECU triggers pyrotechnics, deploying hinged
linkages which raise the rear edge of the aluminium bonnet 100mm in 30ms.
Similar systems on the Jaguar XK, Citroën C6 and Honda Legend use
airbags or sprung-loaded bolts to lift the bonnet. Nissan said that it
chose the hinge solution because “it allows quicker pop-up and stable
operation”.
Nissan’s pop-up bonnet technology is initially for Japan only, where
stringent pedestrian impact legislation is in place. The firm wants to
halve the number of traffic fatalities or serious injuries involving its
vehicles there by 2015 compared to 1995 levels.
The technology will be introduced into other regions later depending on
the needs of the market. Its competitors already offer their solutions
in Europe. The C6 is the first car to be awarded the maximum four star
Euro NCAP rating for pedestrian impact protection. The Legend has a three
star rating.
The UN is considering global legislation. It has found that the top of
the bonnet and fenders are the greatest cause of pedestrian head injuries
and that speeds of up to 40km/h cover more than 75 per cent of all injuries
to pedestrians.
© Automotive Engineer, 2007 |
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