Since the internal combustion engine was born engineers have been developing the concept to make the system more efficient. Having digital control of the key elements that make the engine work (fuel, air and ignition) has provided one of the biggest leaps of improvement. Ignition and fuelling used to be mechanically dispensed through distributors and carburettors but are now electronically controlled using the Engine Control Unit (ECU). Controlling the air supply electronically is the last key element and holy grail to engine designers
Camshafts, which control the opening and closing of the inlet and exhaust valves, are mechanically linked to the crankshaft, meaning that the time and duration of the valve event is fixed and dictated by engine position. Camless engines, which are being developed by a few companies, remove the mechanical link between valve event and engine positon. The valves are instead controlled electronically, so engineers have complete control of the positioning of the valve and as a result, the air supplied to the combustion chamber.
Perhaps the best known example of a camless engine is Koenigsegg’s FreeValve. The company has retrofitted the technology to an existing production engine and results show a 47% increase in torque, 45% increase in power, fuel consumption reduction of 15% and emissions reduction of 35%.
Other key benefits? Removing the camshafts and all the associated timing gear means the engine becomes much more compact and lighter. Valve positon can be optimised for cylinder deactivation to reduce pumping losses. Aftertreatment, such as catalytic converters, can be reduced or even removed. The inlet valves can be used to throttle the engine, significantly improving fuel consumption and reducing cost.
So why haven’t we done this before? Controlling valves electronically is a huge challenge and actuation has been one of the biggest barriers. Let’s take a normal road car engine that revs to 6,000rpm as an example, and bear with me. This means that at redline an intake valve in a cylinder will open and close 50 times every second, that’s one valve event every 20milliseconds. Actuating valves at this speed with the precision necessary in an engine requires a very complex actuation system.
So when will we be driving vehicles with camless engines? Well, FreeValve already has a working prototype, backing from Qoros Auto (a Chinese vehicle manufacturer) and the technology can be used with existing engine architectures. However, car makers are traditionally cautious about adopting unproven technologies, especially in the engine department. I would expect to see the first production version on one of Mr Koenigsegg’s own vehicles first, where production numbers are low and reliability issues can be closely monitored.