Smarter Heads: Replacing Dumb Iron Cams with Smart E-Cams

Opinion


Perhaps ironically, one of the dumbest remaining parts of a modern, electronically controlled combustion engine is the cylinder head. Sure, many of them can alter valve timing and lift, but not infinitely, not very quickly, and never on a per-cylinder, per-combustion-event basis.

Great engineering minds at Lotus, Ricardo, Valeo, and others have endeavored to replace dumb steel camshafts with smart air- or oil-operated valves, but either they drew too much power or lacked the necessary computing power. These barriers are falling. Last year, I covered a hydropneumatic camless valve solution from Koenigsegg called Freevalve that might hit production in a Chinese Qoros vehicle within a year. Then I discovered Intelligent Valve Technology from British tech company Camcon Auto, which strikes me as simpler and therefore better.

IVT is not camless, per se. Rather, the technology opens and closes the valves with multiple desmodromic cams, each powered by its own high-precision, eight-pole permanent-magnet electric stepper motor—no coil or hydraulic springs, no compressed air, and no check valves. Want full lift? Rotate the cam 360 degrees. Want less than that? Rotate it part way and then back again. Unlike the Freevalve concept, this one can create almost any valve opening or closing profile desired, allowing engineers to “calibrate without compromise.” (Camcon also markets it as an engineering tool for developing conventional cam profiles.)

Claimed power and efficiency benefits include reduced pumping losses (no throttle required), 30 percent less cranking torque to start (permitting more frequent auto-stops and perhaps a smaller, lighter starter), selective cylinder deactivation, reduced parasitic losses (most steady-state operating modes benefit from only actuating one intake or exhaust valve), on-demand Atkinson-cycle operation, and infinitely variable swirl, tumble, or “swumble.” Side benefits include packaging (lower valvetrain height, no cam drive) and improved sound—the valves themselves operate more quietly, and opening exhaust valves slightly out of phase prevents their resulting shock waves from reinforcing each other, which could reduce sound-deadening and exhaust-muffling requirements.

The system can operate on 12- or 48-volt electrical architecture, but the demonstrator vehicle (a Jaguar XE with a 2.0-liter Ingenium gas engine) runs on 12 volts. Early testing indicates a 7.5 percent improvement in steady-state running. The latest actuators can fully open in 5.5 milliseconds and are rated for 6,750-rpm operation. The parasitic power draw on the electrical system is a bit higher than that of a conventional crank-driven valvetrain during high-load operation using all the valves at full lift, but under the more prevalent lower-lift single-valve operating modes, the power draw (and certainly the friction) is reduced.

The ultimate efficiency improvement expected with iVT operating all valves and an artificial-intelligence controller tailoring timing, lift, cylinder deactivation, and more on a per-cycle basis is diesel-equivalent consumption (so figure upward of 30 percent).

What about cost? Research by Camcon, Jaguar, and a Tier 1 supplier suggests that at volume production it will cost less than other technologies promising similar savings. Vehicles requiring less CO2 improvement can cut costs further by electrifying only the intake and/or by operating two valves with one actuator.

What if it fails? Because the valves can be opened quicker and stay open longer, Camcon has demonstrated that it can flow enough air to match the stock engine’s power with a lower max lift that prevents piston interference.

Fully independent control enables other cool capabilities—like routing only half of the exhaust ports through a turbocharger to heat the catalyst more quickly and eliminate the wastegate. The lower starting torque and ability to selectively deactivate cylinders make iVT great for hybrids, allowing for more frequent shutoff and battery charging at higher efficiency running on fewer cylinders. With an electric supercharger and the right combustion chamber, it’s even possible to briefly switch to two-stroke operation for peak power. Don’t count out the internal combustion engine just yet.



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