Federal-Mogul Powertrain has developed a new piston cooling technology by creating a sealed-for-life coolant chamber within the crown of its Monosteel heavy-duty diesel piston. Branded EnviroKoolT, the technology allows pistons to run safely at crown temperatures in excess of 100-degrees Celsius higher than today’s limits, working where appropriate in conjunction with high oxidation-resistant steel alloys and protective crown coatings, according to the company.
“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 of Federal-Mogul Powertrain. “EnviroKool enables higher temperatures without compromising the strength or durability of the piston.”
Delivering superior cooling efficiency with minimum weight, EnviroKool is the latest evolution of Federal-Mogul Powertrain’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 EnviroKool technology has enabled Federal-Mogul Powertrain to overcome the temperature limitations of conventional open galleries that 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 of engineering and technology for Federal-Mogul Powertrain. “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 Powertrain. The new technology is so effective that the oil cooling flow to the spray jets can be cut by 50 percent, reducing work for the oil pump, lessening parasitic losses and improving engine efficiency. The heat removed from the piston as a result of the spray jets is additional to that which is conducted away through the pin, piston skirt and ring pack.
Federal-Mogul Powertrain has 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.
“EnviroKool is our latest in a succession of enabling technologies designed to help our customers produce engines and vehicles with a reduced carbon footprint, without compromising longevity, durability or performance,” Westbrooke said.