Camless combustion engine may improve ICE efficiency
By Paul Evans
July 12, 2009
A petrol powered Internal Combustion Engine (ICE) is approx 25-30% energy efficient at the flywheel and around 15% energy efficient at the wheels. There are many losses within the engine itself including friction and waste heat from the combustion process, but Sweden's Cargine Engineering thinks that eliminating the parasitic losses of the camshaft by building a camless engine may help improve energy efficiency. Using pneumatically driven actuators to shoot the valve open the camless engine concept can provide fully variable valve lift and fully variable lift duration without a camshaft in sight.
The system runs on air pressure of 3-16 bar (44-232 psi) and can provide 8mm lift for 5 milliseconds of duration, with a maximum lift of 14mm, and can operate at engine speeds of up to 8000 rpm. The setup consumes 50 percent less space than a conventional DOHC 4-valve layout and reduces mass by 30 percent.
The net power consumption of the air compressor needed to run the system is said to consume less power at low rpm but average out about the same as a camshaft over the entire driving range, consuming more power at high rpm (less than 4kW at 6000 rpm for a 2.0-liter 16-valve four). On a normal driving cycle it consumes less energy than a regular camshaft driven system.
Several development partners have signed on, including supercar-maker Koenigsegg and the Scuderi Group.