A manufacturer is being sought to bring a revolutionary new design of petrol engine to market.
The Merritt engine promises better efficiency than a diesel engine, especially when using lean fuel/air mixtures. It could solve the problem of cutting emissions of nitrogen oxides to levels required by forthcoming EU legislation.
The engine, invented by former Coventry University thermodynamics lecturer Dr Dan Merritt, now managing director of MCC Engines, uses a subsidiary ‘minor cylinder’ off each main engine cylinder, in which fuel and air are premixed for 1.5 engine revolutions before combustion. An extra ‘mush valve’ acts as a piston and controls the flow of mixture into the combustion chamber.
MCC, in which Coventry University and Merritt are shareholders, is looking for a manufacturer to take on the next stage of development.
A year’s development contract with Cosworth in 1996 achieved power, idling-speed and exhaust emission targets.
Further work at Coventry has increased thermal efficiency, said Merritt.
He claimed efficiencies of up to 8% over a turbocharged, direct-injection diesel engine, and 18% over a petrol one. He predicted that these figures could rise to 23% and 45% respectively.
Merritt’s team also discovered that controlled self-ignition is possible, cutting NOx emissions. As the petrol/air mixture makes contact with the combustion chamber’s hot walls, it ignites by compression ignition simultaneously, giving NOx no time to form.
‘We’ve revealed the potential,’ says Merritt. ‘Now it needs a big investment. We need someone to do the rest of the development.’