A new cooler piston design is currently being tested in high temperature engine environments. The new piston is being developed by Federal-Mogul Powertrain. The new cooler design is said to be a first in piston cooling technology by creating a sealed-for-life coolant chamber within the crown of the heavy-duty diesel piston.
The new cooler piston has been branded as EnviroKool The technology allows pistons to run safely at crown temperatures in excess of 100°C higher than current limits. The design uses high oxidation resistant steel alloys and protective crown coatings.
“Future diesel engines with more efficient combustion and greater specific power will have to run hotter combustion chambers, but engine manufacturers are constrained by piston crown temperature limits,” said Gian Maria Olivetti, Chief Technology Officer, Federal-Mogul Powertrain. “EnviroKool enables higher temperatures without compromising the strength or durability of the piston.”
EnviroKool is the latest evolution of Federal-Mogul’s Monosteel technology. An integral cooling gallery is created within a steel piston using friction-welded construction and then filled during the manufacturing process with a high temperature oil and an inert gas, before being permanently sealed with a welded plug.
The newly developed technology has enabled Federal-Mogul to overcome the temperature limitations of conventional open galleries where engines have to use engine lubricating oil as the heat transfer medium.
“The prolonged exposure of engine oil to higher temperatures in the piston oil cooling gallery leads to degradation and carbon build-up, reducing the cooling efficiency and leading to overheating,” said Keri Westbrooke, Director Engineering & Technology, Federal MogulPowertrain. “The superior high temperature properties of the EnviroKool gallery coolant allow it to handle increased gallery temperatures reliably, with the heat subsequently removed from the undercrown, where temperatures are lower, by a standard cooling oil jet.”
With no build-up of carbon in the cooling gallery, heat dissipation remains unhindered for the life of the piston. According to Federal Mogul, the new technology is so effective the oil cooling flow to the spray jets can be cut by 50 per cent, reducing work for the oil pump, lessening parasitic losses and improving engine efficiency, the company.
The heat removed from the piston as a result of the spray jets is in addition to the heat conducted away through the pin, piston skirt and ring pack.
Federal-Mogul Powertrain reckons it has already accumulated more than 1,400 hours of testing on heavy-duty engines fitted with EnviroKool Monosteel pistons. Development programs are underway with several customers on engines scheduled for production launch within the next five years.