Kyle, Pardon my ignorant, irrational excursion into green shock technology. What you are saying here makes perfect practical sense, even though the PS article played it up so nicely. I am a retired designer of large scale power generating systems. No one should have any regard for what I say on that subject either.
Jeff ;-) -----Original Message----- From: Kyle Mcallister [mailto:[email protected]] Sent: Sunday, May 10, 2009 1:09 PM To: [email protected] Subject: Re: [Vo]:Hey Kyle: power generating shocks --- Michel Jullian <[email protected]> wrote: > Even on a perfectly smooth road there must be a lot > of energy wasted > in conventional shock absorbers, whenever you > accelerate, brake, go > round a bend... If it's of the order of 1 kW or even > 100W on average, > then Jeff is right that it's certainly worth > recovering! Energy is only produced by a shock-recovering system when the moving component (piston compressing gas, magnet 'pushing' against an inductor) is moving. When going around a turn, there is a transient when the piston/actuator moves, but then the vehicle is steadily cocked to one side. When it comes back up after exiting the turn, you can get a little more energy back, perhaps. Even with a 4,000 pound car (say, an old Monte Carlo like I used to have), this is not going to be enough energy to sneeze at. What is 4kw? It is nothing at all. Power, not energy. If I can supply 4kW for 0.5 sec, what is that? A 22hp electric drivetrain requires ~16.5kW continuous. And to make matters worse, you'll need more than that for a 4,000 pound car. And the lighter the car, the less force applied to the shocks, and so on. Now, all that aside, the important thing is cost effectiveness to the consumer, not efficiency. We can make the efficient part somewhere else, say, a nice clean generating station. Or a better engine, whatever. Assume 4 shocks at say $25 apiece, which waste this miniscule amount of energy (not power, energy). Assume you replace that with 4 'green' shocks that recover this tiny amount of energy. Each will cost, what? At least a few hundred dollars. How long will they last? Well, Mercedes Benz costs a lot, and they fail more often than Chevy struts do, in my experience. Now factor in whatever control circuitry and wiring is needed to convey this intermittent power to the charging system, protection against transients which might damage the vehicle's ECU, factor in water and moisture getting into the shock, salt water/road chemicals used on northern streets against snow and ice (corrosive), heat conducting up the shock from the brakes, etc. You recover a few kJ (nothing compared to what's require to move the car), increase the manufacturing price of the car a couple thousand $$$, decrease mean time between failure by increasing complexity of the system, increase repair/operating costs, and quite possibly increase the weight of the vehicle. Gas shocks are LIGHT. How light will this be? But I'm just a mechanic, I don't know what I'm talking about. --Kyle
