Diesel-engine manufacturers continue to refine their product offerings in preparation for EPA Tier 4 Interim emissions requirements.
On the day John Deere Power Systems announced the technology solutions it will use to meet the stringent regulations, as well as a new naming convention for its engines, Cummins Engine Co. announced its four-cylinder QSB3.3 and QSB4.5 engines will also meet the 2012 EPA Tier 4 Interim/EU Stage III B standards. Required is at least a 90-percent reduction in particulate matter and up to a 50-percent reduction in nitrogen oxides (NOx) from previous Tier 3/Stage III A requirements.
For all of its engines 75 horsepower and above, John Deere Power Systems will start with its Tier 3/Stage III A PowerTech Plus engine platform – which includes cooled exhaust gas recirculation (EGR) for NOx control – and will add an exhaust filter for reducing particulates. Displacements in this power range include the 4.5-, 6.8-, 9.0- and 13.5-liter in-line, four- and six-cylinder engines – all of which feature a four-valve cylinder head, high-pressure fuel system, turbocharging and an air-to-air aftercooling system.
"After much evaluation and testing, we found that an exhaust filter and the use of cooled EGR, coupled with our proven Tier 3/Stage III A PowerTech Plus engine platform, is the best Interim Tier 4/Stage III B solution for meeting emissions and for delivering the performance, reliability, durability and low operating costs our customers have come to expect from John Deere engines," says John Piasecki, director of worldwide marketing, sales and support, explaining why the avoidance of a selective catalytic reduction (SCR) system. "The single-fluid approach of cooled EGR means the technology will be easy for operators to use, and they won't have to incur the cost of diesel fuel plus the urea required by SCR systems. We are using the most operator-friendly technology available today. We chose to take the route of cooled EGR because we believe it's the right technology at this point in time." (EGR vs. SCR)
The new Deere engine names will capitalize on the PowerTech brand, but add a three-letter suffix that designates the engine's technology package. Examples of the new names are the PowerTech PVX 6.8L (pictured) and PSX 6.8L. The three letters define the engine's technology platform, turbocharger and exhaust filter. All of the John Deere Interim Tier 4/Stage III B engines with ratings 174 horsepower and above are designated "P" indicating the Tier 3/Stage III A PowerTech Plus technology platform. These engines use either a variable geometry turbocharger (designated "V") or series turbochargers (designated "S"); and they also feature an exhaust filter (designated "X").
The next-generation four-cylinder Cummins QSB engines retain the same 3.3- and 4.5-liter platforms as their predecessors and will be supplied as a fully integrated air-intake-to-exhaust system. Low emissions are achieved by using cooled EGR for NOx control and exhaust aftertreatment for removing particulate matter, says the company.
Both the cooled-EGR system and the particulate aftertreatment unit have been specifically developed for the four-cylinder platforms as a more compact and simplified version of the Tier 4 Interim technology previously announced for the six-cylinder QSB6.7 engine. A high-pressure common-rail fuel system employed on the Tier-3 QSB3.3 and QSB4.5 is already capable for Tier 4 Interim and will require no major change, says Cummins. An upgraded turbocharger with electronic control will be utilized to manage EGR flow across the entire engine-rpm range.
"Our four-cylinder development program for Tier 4 Interim was driven by the need to avoid the complexity of increasing displacement or overloading the engines with complications such as dual turbochargers," says Hugh Foden, executive director, Cummins Off-Highway Business. "We have instead focused on minimizing the installation impact for our OEM customers with space-saving solutions such as the Cummins Direct Flow air filtration system, and we've scaled down the EGR and aftertreatment technology appropriately for these compact engines."
QSB3.3 ratings extend from 75 to 110 horsepower for Tier 4 Interim, retaining "best-in-class" power output for this size of engine, says Cummins. The QSB4.5 occupies the 110- to 160-horsepower band and will offer "the same or improved torque delivery" as the Tier 3 version.