Regenerative Suspension

[Foxpaw]

Right then. A friend of mine had an idea at work today. He was thinking about ways to generate energy, or something, and at any rate he asked me if it would be possible to generate energy by harnessing the up-and-down motion of shock absorbers. This would cause some resistance, of course, but that's exactly what you want in shock absorbers.

That got me thinking. If there was an electromagnet (permanent magnets probrably wouldn't work due to lower power levels, but maybe) on the "piston" part and a coil on the "sleeve" part, you could, in theory, do away with the gas chamber deal they've got going now and induce a current in the coil by the moving electromagnet. Of course, the electromagnet would probrably only be powered when the suspension was detected to be in motion, to save energy.

Anyways, this seems like a sound idea to me. However, I don't know how much energy may be recoverable in this manner. Also, there may be some manufacturing or other basic flaw in my thinking here. To that end, I'm posting the idea here looking for some feedback. Could this work, and/or would the amount of energy produced (assuming somewhat bumpy roads) be significant?

[Corey872]

That is an interesting idea...and I suppose technologically feasable. I believe some of the higher end sports/luxury cars already have a type of "electric" shock. An electric current is sent through a fluid which then changes the viscosity of the fluid. Your idea would be an adaptation of that to some extent.

I'm not exactly sure how to go about calculating the energy...at sometimes you would have essentially the entire car swooping down a couple of inches, at others I could see how only one tire would bounce into a pot-hole and the car body and (other three shocks) would remain essentially stationary. The one thought I do have, though, is that since normal car shocks don't make any provision for heat dissipation and don't really get hot enough to require any special treatment, the amount of energy generated would probably be pretty low. We'll see what others have to say.

[Holicow]

The new Corvette (and the 50th Anniv. edition) have the option of the electrically-controlled shock fluid (I can't remember their name for the stuff, but it is cool). I don't think it is yet used on any other car. Some high-end cars have "dynamic ride control" where there is a remote reservoir and all the shocks are plumbed together, and the damping is controlled in a diagonal pattern by sensing wheel travel.

I am all for capturing available energy (that's probably the main reason I have this car). I don't see this kind of system being very productive, in a "return-on-investment sense", but that's not the whole ballgame. Now, if a suspension-regeneration system makes the price of the car 100 grand, I would have to pass. Reality will always win.

[Tim Maddux]

Sounds like a linear generator is what you are suggesting. I think the biggest drawback for an Insight would be the relatively small travel in the suspension.

[b1shmu63]

Sure it would work and if properly designed it would not ad to the weight of the car. Rare earth magnets could be used to achieve high flux density. (They are used in the IMA.) Greatest gains would be achieved on rough roads of course. The drver could dial in sporty or smooth suspension as a bonus. Accounting for system losses you would probably see less than a 1 MPG improvement, but it all adds up. If you coupled this with solar and thermo electric exhaust recovery you would start to see some real numbers.

[Holicow]

Here it is, thanks to Bose:

Bose Suspension

[bretthans]

The Bose system is similar to other electronic suspensions found in luxury vehicles and is designed for ride control. It will consume energy, not recover energy, and does the opposite of Foxpaw's original intent, but, hey, the ride would be better. Bose has done something uncommon in that energy can be recaptured on the return travel to offset energy consumed on the extension. This reduces the overall consumption to, according to them, less than 1/3 the energy of a "typical" vehicle air conditioner.

I thought of recovering energy from the potholes once (we have plenty) and with a quick search on the web found that some have tried to do what Foxpaw is suggesting. I don't remember any sites off the top of my head but they were typically part of college research or solar vehicle design projects.

With the short travel of the Insight suspension, it may be very difficult to offset the extra weight of such a system with the recaptured energy. That and you would need some way to deliver that energy to the electrical system, further adding weight, cost, and complexity. Nonetheless, it would be an interesting project.

[b1shmu63]

I think that the Bose system is still experimental, but if you could get one it could be set up to run as a passive system that recovers energy with out using energy. Bose could never market it as a passive system as no one would buy it except for a few hypermileage enthusiasts.

[boogetyboogety]

How funny you would mention gathering energy from shock absorbers. You brought back some long-forgotten memories for me...

Remember, Arthur C. Clarke could have become one of the wealthiest people in the world if he had patented his concept of a geosynchronous earth satellite when he first conceived the idea in a novel. So remember that when I give you these ideas of mine... for free.

I had thought about using shock-absorber-generated energy to recharge batteries years and years ago, when a buddy of mine and I sat around one beery evening thinking about the ultimate electric car. Our goal was: Nothing less than perpetual motion for unlimited driving range. Stop scoffing here, and hear me out:

No one system can generate more energy than goes into it, of course. But how about stacking systems on top of systems to achieve your end? We now have only the IMA system, recharging batteries from braking and from normal ICE operation on the hybrids... But consider this: Build a plug-in-at-night-or-while-at-work EV with rechargeable, high-energy lightweight batteries (with an admittedly better performance than what's now available... we were thinking far in the future, like in 2005 ). Use the braking system to recapture energy to recharge the batteries, add shock absorber-based energy capture, little air wheels inside the grille for even more energy capture, solar panels on top of the car for sunny days, use some system to capture heat on sunny days and cold on wintry days and convert same to electricity for the batteries, and for extra measure of safety in emergency situations (there were a lot of beers consumed that day), a small lawn-mower-sized engine in the trunk with its own fossil fuel supply (and we even considered stationary-bike pedals in the back seat wheel wells to make the kiddos earn their keep) to get you back from the imaginary boonies to a charging station somewhere, so you could get home regardless of the situation.

As I remember, my headache the following morning was a bit more exquisite than usual... but I've always regretted not following up on my ideas to see their real-world possibilities. Any sober engineers out there want to shatter our hopes and dreams?

[Holicow]

Originally Posted by bretthans

The Bose system is similar to other electronic suspensions found in luxury vehicles and is designed for ride control. ...

Not really. The "adaptive" suspensions on high-end performance and luxury cars only have controllable valving in the dampers or something of the sort. They still have springs, and dampers...old tech.

the Bose system does away with springs and dampers, and uses only these linear motors to do the job. I think it's way cool, and the fact that it can regenerate enery is also cool, except that they probably use more than they make.