Cam less I.C. Engine

Most piston engines today employ a camshaft to operate poppet valves. This normally consists of one or more shafts parallel to the crankshaft with a number of oblong lobes or cams protruding from it, one for each valve. The cams force the valves open either by pressing directly on the valve stem, or by operating some intermediate mechanism. (Exceptions to this system include the two-stroke and Wankel engines, which use piston-controlled ports).

Sliding friction between the surface of the cam and the cam follower reduce the ultimate power of the engine. While attempts have been made to combat this with rollers (which also permit the use of concave cam lobes), there are more frictional losses in the tappet blocks and valve guides. Then there are the losses in hysteresis, whereby not all of the energy used to compress the valve springs is returned as the spring extends again. All these reduce the overall efficiency of the engine. And, of course, camshaft/spring operation introduces valvetrain weight, limiting the rotational speed at which the engine can operate.

One of the approaches designed to overcome these problems, but which has proved difficult to implement, is Camless valvetrains using solenoids or magnetic systems which have long been investigated by BMW and Fiat, and are currently being prototyped by Valeo and Ricardo. The new Fiat Nuova 500 is supposed to have this kind of engine^[1].

The earliest proposed system was on the Tucker Torpedo in 1947, which was planned use oil pressure to open the valves. However, the engine didn't reach production due to legal problems.

Camless engines would not only be more efficient in terms of mechanical energy, they would also be more flexible, as the valves could be computer-controlled and free up more power to the wheels. Infinitely variable valve timing would be possible, though variable valve lift would be more difficult. Valeo estimates that the efficiency of a camless engine would be 20% greater than a comparable camshaft-operated engine, though Ricardo is more conservative. These companies are positioning this technology as an alternative to hybrid engines currently used to increase fuel economy.