Valve control is fundamentally compromised on conventional engines. But that’s all changing with the arrival of infinitely variable valves. By Ian Adcock
IMAGINE A VALVE control system without compromises, one that isn’t crank-driven and doesn’t play by conventional rules. Such an engine would allow infinitely variable timing on all its valves, independent of one another, meaning it could effectively tune itself on the move, boosting power and efficiency. It could also offer cylinder deactivation, eliminate a turbocharger’s wastegate, switch between four- and two-stroke cycles and even run as an ingenious, very efficient 12-stroke.
Camcon, a Midlands-based firm, is working on intelligent valve actuation (IVA), which is now attracting the attention of big component manufacturers, and is predicted to be in production for mainstream cars within the next five years. Prototypes are showing a fuel consumption improvement of up to 7.5 per cent.
IVA employs a four-phase rotary actuator driving a separate camshaft for each conventional poppet valve. A desmodromic linkage connects this camshaft to the valves. All aspects of the valve timing are independently and infinitely variable, with full feedback control, allowing features such as maximum opening position shifting, lift-dwell return, double and missed events, roaming cylinder deactivation and control of both combustion chamber swirl and tumble.
Because it’s an active system, Camcon is still discovering the system’s potential, as Camcon’s Roger Stone explains: ‘It could unlock homogenous charge compression ignition [a very efficient, diesel-like combustion process], and both the Miller and Atkinson cycles respond well to IVA.’
And that 12-stroke system we mentioned? In motorway cruising, every cylinder fires only every third stroke, which is potentially cleaner than cylinder deactivation since there are no CO2 spikes as cylinders are reactivated.