Damage Avoidance
THE MAGAZINE DEVOTED TO NICKEL AND ITS APPLICATIONS
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IN THIS PATENT, the hood (12) of a car would be lifted by a rod (24) which is connected to a so-called
'active' material (18) such as NiTiNOL. The shape memory alloy is joined by a connector (22) to a device
which activates it by a thermal signal. In the event of a crash, the activation device sends an electrial
signal which changes the temperature of the shape memory alloy causing it to contract, thereby increasing the
clearance distance (20) between the hood and the engine (16) by pivoting about a hinge point (14).
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CRUMPLED HOODS such as this could result in less damage to an engine if the hood were to be lifted during
a collison.
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Our nickel patent-of-the-month features greater safety for car drivers
By Dean Jobb
Nickel Magazine, July 2006 -- A nickel alloy could be an integral part of a newly-patented mechanism to make engine hoods, trunk lids and other vehicle components more crash-resistant.
General Motors (GM) was issued a patent in June 2006 for a hood lift mechanism that uses so-called "active materials" to lift and tilt parts of a vehicle when crash sensors are activated. The addition of a shape memory material – Nitinol ( N01555), a 50-50 blend of nickel and titanium, is among the favoured alloys – would allow the components to return to their original shape in minor crashes, avoiding costly repairs.
In its filing with the United States Patent Office, GM notes that engine hoods (or "bonnets," as they’re known in the U.K.) and other hinged vehicle components are made of thin sheet metal supported by stamped ribs. Efforts to make vehicles more aerodynamic and fuel-efficient, as well as sleek and stylish, require that front-end hoods be extremely close to the engine components beneath them.
If a vehicle is involved in a collision, the hood is unable to absorb as much of the energy of the crash before bottoming-out against the engine. That’s where a hood lifter comes into play: activated by impact sensors, it increases the space between the hood and the compartment it covers.
"The hood lifters change the orientation of the hood by raising it above the engine compartment," GM notes in its patent filing. (In most mechanisms, the hood is raised at a rear edge while maintaining attachment of a front edge to the vehicle structure.) "Because of the increase in clearance, there is an increase in the amount of the energy that can be absorbed by deformation of the sheet metal before bottoming out."
There’s one drawback: if the lifting mechanism is activated in a minor fender-bender, the hood would have to be replaced or repaired. Still, the addition of shape memory materials, which deform and reshape in response to variations in temperature, means the mechanism can return to its original shape as soon as crash sensors are de-activated.
The patent states that the technology could also be used to build passenger doors, trunk lids, fuel tank lids, cargo hatches, and lift gates.
Millions of vehicles could potentially be equipped with the lifting mechanism. GM officials say each mechanism would use about 50 grams of nickel-containing material.
For the shape memory alloy, patent number 7,063,377 specifies Nitinol. (NiTi is the trade name for a nickel-titanium alloy; NOL stands for Naval Ordnance Laboratory, which is where the alloy was discovered in the 1960s.) The shape memory is commercially available from California-based Shape Memory Applications Inc.
The patent also specifies nickel-aluminum and nickel-gallium alloys as candidates for the shape memory material, along with a long list of alloys of copper, platinum and cadmium, and shape memory polymers such as thermoplastics.
The patent is assigned to General Motors and the University of Michigan. The inventors are Diann Brei, John Redmond, Nathan A. Wilmot, Alan L. Browne, Nancy L. Johnson and Gary L. Jones.
Dean Jobb is a Halifax, N.S.-based freelance writer.
PHOTO: istockphoto
U.S. Patent Office |
