• Feb 1, 2009
Scientists at Tufts University have patented a shock absorber that converts compressive energy into electricity, which can then be stored in a hybrid vehicle's batteries. Called the Power-Generating Shock Absorber (PGSA), actually an electromagnetic linear generator, it uses "magnet arrays, high magnetic permeability spaces, coil winding arrays," and a linear electric motor to capture the energy of its motion and use it to charge the batteries.

The movement of a standard shock absorber creates heat, which is neutralized by the oil in the shock. In a PGSA, a linear electric motor converts the magnetic field created by the repetitive motion into electricity. Or, if you like your technology to sound science-y, it "uses an electromagnetic linear generator to convert variable frequency, repetitive intermittent linear displacement motion to useful electrical power."

The technology can be used on any vehicle that uses shocks and batteries, but its greatest application could be on trucks due to their higher mass and electricity-generation potential. Electric Truck, LLC has licensed the shock technology, which is predicted to generate between 2kW and 17kW of energy on an average road. According to the men who created it, "the percentage of recoverable power/energy for a 2,500 lb vehicle that employs four optimized design regenerative magnetic shock absorbers and whose average speed is 45 mph on a typical US highway is likely to be between 20." Put four of those on a Prius and stay in town, and all of a sudden you're talking about interstellar gas mileage. Thanks for the tip, Paul

[Source: Gizmag via iCars]


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  • 44 Comments
      • 5 Years Ago
      Now for someone to devise a way to efficiently convert dissipating heat from the breaks into electrical energy :)
      • 5 Years Ago
      So those lowriders will now be perpetual motion machines?
      • 5 Years Ago
      This is a great idea. Every bit helps, and unless your road is smooth as glass, these will work well.
      • 5 Years Ago
      Turning and braking also modulate the shock. My assumption is that there still will be damping (it could be air damped), however it will generate electricity via the magnets passing the coils.
      • 5 Years Ago
      I’m honestly surprised no-one has thought of this before. Once it’s fully developed it shouldn’t be complicated in design or manufacture. Magnetically damped shocks are nothing new, this just goes a step further to re-capture energy.

      There is another benefit, this type shock absorber easily lends itself to variable dampening control.

      • 5 Years Ago
      So, basically the energy in a normal shock goes into heating the oil and springs. Add some magnets, and that energy creates electricity instead of heat... but you're not creating energy, just changing its form. The amount of electrical energy should equal the amount of heat energy (roughly). Unless a normal shock gets REALLY hot during use, doesn't seem like there would be enough energy there to make any difference.
      • 5 Years Ago
      Very cool. I'm curious as to how much extra cost this would add to a vehicle.
      • 5 Years Ago
      I am no physicist but it seems that if you are on descent roads the amount of energy gained back would be negligible.

      Basically it looks just like one of those LED shake up flashlights that you charge by shaking the magnet through some windings. I am sure its allot more complicated but thats what it looks like.
        • 5 Years Ago
        Well it is exactly the same principle, which is called "Faraday's law of induction", that is used to generate all the electricity you use in the daily life. The amount of electrical energy produced would depend on how much dampening force the shock will be producing times how far the shock can travel, thus the suggestion of usage on heavy trucks. There are hand crank flash lights that give you instant power but are quite hard to keep on winding vs the once charged by almost effortless shaking. The real question here is how feasible this things can be in cost/durability/benefit.
        Cheers.
        • 5 Years Ago
        quote from JZeke: -
        "Actually, I did a sketch of this concept 2 years ago, and a buddy of mine and I thought to patent it. Turns out, there were already 2 patents pending when we were researching it. Cool idea, hope it works out for these guys" -

        I know the feeling. I had an idea for basically the reverse of this(essentially electromagnetic shocks). It was all just thoughts in my head and sketches and then one day I found out about the Bose Suspension System(http://www.bose.com/controller?event=VIEW_STATIC_PAGE_EVENT&url=/learning/project_sound/suspension_challenge.jsp) which they had apparently been working on for quite soem time already. Plus, a few years later, GM introduced their magnetorheological suspension on the Corvette which is a similar idea but more simple and conventional.

        I think this idea has at least some merit. It may not offer as much energy as regenerative braking, but it can also be used far more often. Consider taking a long trip, how often do you use the brakes? Now how often is your suspension working?
        • 5 Years Ago
        You'd be better off with a regular car getting over 20 mpg. The cost of all these regenerative technologies would make the parts so expensive that maintenance would be a nightmare.

        Its nice for them to be thinking in this manner but this technology is better served generating electricity from ocean current.
        • 5 Years Ago
        The idea for this is simple, I'm surprised that no one has thought of it until now.
        • 5 Years Ago
        asus: "Well for those of us who live in broke states that don't fix the roads, this seems like a good idea. :-)"

        Assuming these can take that sort of punishment, and I'll bet these won't be cheap...

        • 5 Years Ago
        Actually, I did a sketch of this concept 2 years ago, and a buddy of mine and I thought to patent it. Turns out, there were already 2 patents pending when we were researching it. Cool idea, hope it works out for these guys.
        • 5 Years Ago
        Weight transfer loads and unloads your vehicle's shock absorbers every time you accelerate, brake, and turn.

        Also, watch a vehicle's wheels the next time you're on a "smooth" highway. At 80 mph, your vehicle's shocks are working pretty hard to digest even small surface variations as their frequency increases.
        • 5 Years Ago
        I don't think going downhill would make a difference.

        • 5 Years Ago
        Well for those of us who live in broke states that don't fix the roads, this seems like a good idea. :-)
      • 5 Years Ago
      Like ccdoggy (snicker) I am not a physicist, but I think everyone's misinterpreting this:

      ""the percentage of recoverable power/energy for a 2,500 lb vehicle that employs four optimized design regenerative magnetic shock absorbers and whose average speed is 45 mph on a typical US highway is likely to be between 20% and 70%"

      I think they mean they can recover 20-70% of the energy expended vertically, which is probably only a very small amount of the cars expended energy overall (although, presumably, it's an energy amount worth going after, or these guys wouldn't be in the business).

      Put it this way - assume a car consumes a gallon of gas and produces X amount of energy from it (we're talking after losses). I would suspect that most of the produced energy - like 90% - is spent towards forward motion. Some of that get's wasted/lost in other residual effects - like going over bumps - but that's out of the remaining 10%*. So I think they mean they can recover 20-70% of the 10%, not 20-70% of the 90, or 100%.

      (* my presumption that 90% is spent towards forward motion and 10% wasted/lost in other travel may well be off. Either way, the 20-70 probably comes out of what is not consumed by forward motion, whatever that is...)
      • 5 Years Ago
      This reminds me of those battery-less self powered flashlights that you have to shake up and down for them to work. Similar concept?
      • 5 Years Ago
      this should be part of the stimulus package. Obama is definitely making things better already. Bush would never allow something like this. I'm glad science is back!
        • 5 Years Ago
        So I would have an excuse to go fast over speed bumps?
      • 5 Years Ago
      It seems these would, as the article mentions, be most efficient in trucks due to the massive weight/force they would place on the shocks and the fact that there's probably plenty of space and not much emphasis on weight efficiency for this kind of part.
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