The MIT Technology Review has an article entitled "Why Not a 40-MPG SUV?". It reviews a number of promising technologies that could make the standard internal combustion engine vehicle much more efficient. For example, electromechanical actuators could replace standard camshafts for controlling valve opening:
But the ultimate move toward optimization throws the camshaft away. Instead, electromechanical actuators would provide software-driven control for each valve (see “The Camless Engine,” below). By providing full control over the timing, lift, and duration of each valve motion, such a camless engine optimizes power delivery with the least possible fuel at every engine-rotation speed. The payoff is huge: a camless engine could improve fuel economy by 10 to 18 percent while also increasing engine torque by 15 to 20 percent at low speeds for faster acceleration.
The problem is that to prevent excessive wear and minimize engine noise and vibration, valves must decelerate before landing. A camshaft, though relatively inefficient, does this quite well, thanks to its ovoid shape, which produces a corresponding acceleration and deceleration in the valve motion. Actuators are different; they slam up and down, on and off.
The way to make actuators as gentle as camshafts involves a combination of hardware and software, and many companies are working on the problem.
It is surprising just how much more refinement can be done to the design of the internal combustion engine.
|Share |||Randall Parker, 2002 November 11 07:58 PM Energy Transportation|