A new valve technology developed at the University of Waterloo may lead to more affordable — and more environmentally friendly — engines.
According to the inventors, the patented VVA (Variable Valve Actuation) system could increase the efficiency of an internal combustion engine (ICE) by more than 10 percent and reduce fuel consumption in ships, compact cars, and other large vehicles.
The university’s engine idea — one developed over a span of almost ten years — replaces a common ICE component: the cam.
Often a rotating or sliding piece in a mechanical connection, the camshaft of a vehicle transforms the engine’s rotary motion into the linear motion that operates the cylinders’ intake and exhaust valves.
So, what’s the problem with the cam?
To maximize the energy transfer to the piston, the timings of the valves need to be synced to the combustion process. All high-performance engines have some limited forms of variable valve timing.
The cam-control mechanisms in internal combustion engines do not allow the timing of the valves’ opening and closing to fluctuate
The new setup from the University of Waterloo, led by mechanical and mechatronics engineering professor Amir Khajepour, eliminates the camshaft, cams, and the drive system.
By swapping cams with hydraulic cylinders and rotary hydraulic valves, variable timing is enabled as the speed and torque of an engine change.
The engine valves are directly connected to small hydraulic cylinders that are driven by rotary valves. The rotary valves are run by the crankshaft, making them fully failsafe, said Professor Khajepour.
“It is simpler because we use a rotary valve that does not need any electronics and complex control to drive it,” Khajepour told Tech Briefs.” The rotary valve is driven directly by the crankshaft.”
Timing the opening and closing of valves to engine operation – and maximizing energy transfer – increases fuel efficiency, reducing both costs and greenhouse gas emissions.
The technology developed and tested at Waterloo could be especially valuable for bigger vehicles, like trucks and mining equipment.
“It can be used on any engine,” said Khajepour. “However, it will be first more effective on large engines where any improvement on fuel economy accounts for a large saving.”
After testing the new VVA on an actual engine, Khajepour and his student team are currently seeking an industry partner to evaluate the system on a production engine.
The hydraulic variable valve system study, which builds on research that began in 2008, appears in the journal Mechatronics.