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To form the EnviroKool crown, an integral cooling gallery is created by friction welding within the crown of the cast and forged piston, and then filled with high-temperature oil and an inert gas.

New Piston Cooling Technology for Heavy-Duty Diesel Engines

July 12, 2016
Federal-Mogul Powertrain’s “sealed-for-life” coolant chamber allows steel pistons to run 100°C hotter Monosteel pistons for heavy truck, industrial engines Future diesel engines will have to run hotter +1,400 hours testing completed

Federal-Mogul Powertrain is preparing to introduce a new steel piston for diesel engines it has designed with a “sealed-for-life” coolant chamber in the crown, allowing the pistons to operate safely at crown temperatures more than 100°C higher than current limits.

“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,” stated chief technology officer Gian Maria Olivetti. “EnviroKool enables higher temperatures without compromising the strength or durability of the piston.”

The EnviroKool technology is designed for Federal-Mogul’s Monosteel pistons for heavy-truck and industrial diesel engines, which are formed from forged and cast steel sections.

To form the EnviroKool crown, an integral cooling gallery is created within the piston using friction welding, and then filled with high-temperature oil and an inert gas. This chamber is permanently sealed with a welded plug.  According Federal-Mogul Powertrain, EnviroKool makes it possible to overcome the temperature limitations of conventional open galleries that use lubricating oil as a heat-transfer medium.

The developer indicated it has completed more than 1,400 hours of testing for the EnviroKool Monosteel pistons on heavy-duty engines, and development programs are underway with several customers on engines scheduled to begin production within the next five years.

“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,” explained Keri Westbrooke, director of Engineering and Technology. “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.”

Because there is no build-up of carbon in the cooling gallery, heat dissipation is unhindered for the life of the piston. Federal-Mogul stated the new technology is so effective that the oil cooling flow to the spray jets can be cut by 50%, reducing work for the oil pump, and improving engine efficiency.