New system revs up efficiency of internal combustion engines

Wednesday, May 2, 2018

Amir Khajepour (right) works with students in his lab at Waterloo EngineeringA decade of research at Waterloo Engineering has yielded promising new technology to boost the efficiency of internal combustion engines.

Validated tests in the lab have shown gains of more than 10 per cent for a patented system to open and close engine valves, an innovation that would save money while also reducing greenhouse gas emissions.

Both simple and reliable, the technology could significantly reduce fuel consumption in everything from ocean-going ships to compact cars.

“This method has the potential to bring the well-established benefits of a fully variable valve system out of the lab and into production engines because cost and complexity aren’t issues,” said Amir Khajepour, a professor of mechanical and mechatronics engineering who led the research.

Intake and exhaust valves in internal combustion engines are typically controlled by cam mechanisms that do not allow the timing of their opening and closing to be varied.

The technology developed by Waterloo researchers replaces cams with hydraulic cylinders and rotary hydraulic valves that enable fully variable timing as the speed and torque of an engine change.

That ability to specifically time the opening and closing of valves based on engine operation is a key to reducing fuel consumption.

“If you think about an ideal solution, it is to make the motion of the valve completely controllable,” said Khajepour, a Canada Research Chair and director of Waterloo’s Mechatronic Vehicle Systems Lab. “That gives you infinite options to work with.”

Although other systems to vary valve timing exist, they are limited to use in experimental engines in laboratories due to their high cost and complexity.

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