"Their prototype shock absorbers use a hydraulic system that forces fluid through a turbine attached to a generator"

Isn't there a better non-mechanical method other than a turbine?

In the course of my day job, I have analyzed and studied active and semiactive suspension systems as an alternative to passive suspensions like we now have on most cars.

Semiactive suspensions are basically, shock absorbers which can vary their damping coefficient rapidly, so as to offer resistance to motion when we want it, but not when we don't. Said devices can use variable orifices, or they may utilize electrorheological or magnetorheological fluids whose viscosity may be varied rapidly simply by varying an applied electrostatic or magnetic field. Magnetorheological fluid based shock absorbers have been used on some cars, i.e. Cadillac sport sedans.

The ultimate in technological sophistication, suspension-wise, is a fully active system where we input energy into an actuator so as to counter unwanted body motion. Such actuators may be hydraulic or electromechanical. Ford Motor Company, years ago, patented an electromechanical active suspension actuator. Bose, the outfit known for consumer electronics, also developed an electric active suspension actuator. Active suspensions require energy input, and have been criticized for costing too much and compromising fuel economy because of their energy requirements.

Suppose one were to take an electromechanical active suspension actuator, and connect the wires to a resistance, and then apply motion to it. It would act as a generator, and the resistor would get hot. By varying the resistance, one could vary the effective coefficient of damping. Now suppose we take the electric energy thus generated, and use it for some useful purpose instead of just converting it to heat in a resistance. Voila! You have an electromagnetic regenerative shock absorber.

What those MIT students came up with, is a hydraulic regenerative arrangement. A purely electric arrangement like I described, would attain semiactive suspension functionality without hydraulic fluid and regenerate energy that would otherwise be wastefully converted to heat.

I think said idea is worth exploring.

@GreenPlease and the group:

Some clarification is in order regarding suspension systems. There are passive systems, semi-active suspensions, and fully active suspensions. The first, is just your basic combination of spring, mass and damper. Actually even a simplified model requires an unsprung mass, sprung mass, a spring and damper (shock absorber) between said masses, and a mathematical model for the tire which could be just a spring, or both a spring and a damper.

A semiactive suspension uses a spring and a damper whose damping coefficient is rapidly variable. A computer controlled system, by varying the damping coefficient in the right manner at the right time, can result in improved comfort for the passengers by reducing undesired body motion. In a semiactive system, there is no energy input except for that required to adjust the damper rapidly.

With a fully active suspension system you need an actuator which provides a force input to the unsprung mass/sprung mass system to counteract unwanted sprung mass motion. This system requires external energy, which comes from the engine in one form or another. The result is, you compromise fuel economy because an active suspension's power demand is an added load on the engine.

With passive and semiactive systems, the spring (coil or leaf) compresses to absorb bumps, then re-levels the car. You need a damper of one form or another, to dissipate energy that would otherwise result in the car bouncing up and down repeatedly every time you hit a bump in the road.

What I proposed in my earlier post and what the MIT students are proposing, is a semiactive system which feeds suspension energy into the vehicle's electrical system instead of dissipating suspension energy as heat, as a conventional shock absorber does and as a semiactive system also does but in a more sophisticated manner.

An electric active suspension actuator can transfer energy in either direction, i.e. from the vehicle electric system to the suspension, or the other way around. We can operate said device in either fully active mode, or in semiactive mode. In the latter mode, we get the benefits of semiactive suspension operation without the power consumption of a fully active suspension. In fact with such an arrangement, we feed a little energy into the vehicle power system, so we should get a slight increase in fuel economy.

This is a brilliant idea! Esspecialy for any place with significant frost heaves like here in Canada! The fact that they are getting significant amounts of power out of it is great, normally this energy is lost as heat so why not?

Now many of you are suggesting the logical next step which is a fully electromagnetic regenerative shock absorber but the current hydraulic unit is a good start. They mention that if the electronics fail somehow this still functions as a regular shock absorber, very important. A fully electromagnetic unit would not have this backup. Think of it like regenerative brakes, with wheel motors you theoretically don't need mechanical brakes any more right? I doubt we will see an electric car with no mechanical brakes anytime soon though, probably never. We may see a car with electromechanical shocks though, but this is a good incremental step. I imagine the magnets and wiring required for a straight linear electromagnetic shock with enough damping force would be rather large, heavy and expensive, any ideas? Unless some levers/gearing are used to turn it into rotational motion. This is a great start though and I hope they can develop it further without too much patent hassel etc.

The fact that chose to do it through an hydraulic appraoch is rather surprising but that's a brilliant idea and achievement indeed. On overwhole when you sum up, start and stop, regenerative braking, waste damping recovery and also waste heat recovery you are talking about big saving

rihcw930

Waht you propose is called "perpetual motion" and consequently doesn't work, you will create more friction than the energy you get my friend. What they propose here is totally different, they tap in wasted energy, if you start to tap in the non wasted energy then it doesn't make any sense. Automatic watches tap into non wasted energy but a tiny winy amount so you don't feel it, but strictly speaking you spend more energy to move your arm when you wear an automatic watch than when you wear a battery powered watch.