Harnessing the Energy of Shock Absorbers
Filed Under: green automotive technology, Green Technology on December 10, 2009
While most of the effort, up to this point, in shock absorption technology has gone into making them smoother to provide a better ride, until five MIT students starting thinking about it. They decided that there was a lot of energy being wasted and they should figure out how to harness it.
So they did.
GenShock was the result. After two years of work, the team has built prototypes, tested the theory, were given a Hummer to try it on, and are now going into negotiations to test the GenShock on the military’s Humvees.
The idea is pretty basic and the way it works is simple enough. Basically, they started with a hydraulic shock and modified it to their purpose. Every time the shock absorber compresses, the piston pushes upwards and is resisted by the hydraulic fluid (under pressure) inside. They added a generator to harness the hydraulic fluid as it compresses and moves, and a few changes to the shock absorber itself in order to facilitate more movement of the fluid without dampening the shock’s ability to absorb bumps and holes.
After a few iterations, a shock absorber that replaces standard shocks on the vehicle. On the Hummer test platform, they’re getting 800 watts from each wheel or about five kilowatts from the vehicle. Way more than the alternator makes on its own. They plan to double that with the next prototype.
Without engine modifications, this could save 2-5% of the fuel mileage on a commercial truck, for instance, by providing more power to charge batteries and allowing the truck’s alternator to be less resistant on the belt drive from the engine. They’ll have to figure out how to make this work as a replacement for airbags (the “shocks” most trucks use now), first, though.
When one of the boy’s professors brought the invention to the attention of a friend, Retired General Paul J. Kern, head of AM General, who makes the Humvee, the General was interested. He provided them with a test bed and when the boys delivered, a contract was underway.
Working in between classes in a rental warehouse, the team has been working with the loaner Humvee, adding the shocks, putting in data collection gear, and working out the bugs. The final product must survive totally submerged, last the lifetime of the vehicle, and produce no electrical noise that could interfere with other equipment.
The boys are now talking to the Office of Naval Research, the Army’s Tank Automotive Research, Development and Engineering Center, Navistar and Mack Trucks, and others. The boys all graduated this year and are now working full time on the GenShock system.
If it pans out, they may not have to ever write up a resume’.
