John Deere Power Systems (JDPS), Waterloo, Iowa, has announced the technology solutions it will use to meet Interim Tier 4/Stage III B mobile off-highway emissions regulations for engines 174 hp and above. These emissions regulations, which begin in 2011, require a 90-percent reduction in diesel particulates (PM) and a 50-percent reduction in oxides of nitrogen (NOx) from previous Tier 3/Stage lll A requirements.
To achieve compliance with these emissions regulations, John Deere will start with its proven Tier 3 PowerTech Plus engine platform, add a diesel oxidation catalyst (DOC)/diesel particulate filter (DPF) unit for reducing particulates, and increase the percentage of cooled exhaust gas recirculation (EGR) for NOx control. John Deere will not use selective catalytic reduction (SCR), an alternate NOx reduction technology, for Interim Tier 4 because the EGR and DOC/DPF technology path is more proven, simpler and less costly to operate, according to the company.
PowerTech Plus engine models in the 174-hp and above power class include the 6.8L, 9.0L and 13.5L in-line, six-cylinder engines, all of which feature a four-valve cylinder head, high-pressure fuel system, variable geometry turbocharger (VGT) and an air-to-air aftercooling system. For Interim Tier 4, the cylinder head, fuel system, EGR, VGT and air-to-air aftercooling systems will be updated but will be similar to Tier 3 configurations. The engine control unit will change substantially to provide twice the RAM, double the processing speed and four times the program memory of the previous version to handle requirements of added sensor and control logic.
“After much evaluation and testing, we found that a DOC/DPF and increased use of EGR, coupled with our proven Tier 3 PowerTech Plus engine platform is the best Interim Tier 4 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,” said John Piasecki, director of worldwide marketing, sales and customer support for JDPS.
John Deere has developed its DOC/DPF unit specifically to meet the demands of off-highway applications. The DOC component reduces carbon monoxide, hydrocarbons and some particulate matter. The downstream DPF traps and holds particulates remaining in the exhaust stream. Trapped particles are eventually incinerated within the DPF through a process known as regeneration. In most cases, the regeneration process will not have an impact on machine operation and will not be noticeable to the operator. Another benefit of the DOC/DPF is that it replaces the need for a muffler in most applications.
Interim Tier 4 regulations require engine manufacturers to also consider crankcase emissions, which must either be managed via a crankcase filter or must be counted in the total engine emissions. The next generation of John Deere engines will be equipped with either a closed or open crankcase ventilation system (CCV/OCV) to manage these crankcase emissions.
Below 130 kW (174 hp), and Final Tier 4/Stage lV
Interim Tier 4 emissions regulations for engines from 56 kW to 129 kW (75 hp-173 hp) are effective in 2012. While it's too early for full disclosure, Piasecki did say, “John Deere is evaluating EGR and DOC/DPF, as well as other technologies for meeting emissions for the lower horsepower categories, and while we're not ready to make any announcements, our technology decision will be based on what we feel will be the best overall value for the customer. John Deere was successful in offering multiple technology solutions to match market needs for Tier 2 and for Tier 3, and we'll likely do something similar for Interim Tier 4. What I will also say is that you are not likely to see the use of SCR on any John Deere engine for Interim Tier 4.”
Already compliant
Six ratings from the John Deere PowerTech M and PowerTech E engine lineups already meet Interim Tier 4 and Stage III A emissions requirements. In early 2007, JDPS announced that PowerTech M 2.4L engines and PowerTech E 2.4L engines under 75 hp are Interim Tier 4 and Stage III A compliant.
PowerTech M engines are designed for lower horsepower applications. Their design and mechanical controls give OEMs and end users additional flexibility and cost savings while maintaining the same engine platform as Tier 2/Stage II engines. PowerTech M 2.4L engines feature 2-valve cylinder heads, fixed-geometry turbochargers, self-adjusting poly-vee fan drives, a mechanical unit pump fuel system, 500-hour oil changes and turbocharged aspiration.
Four new ratings of the PowerTech E 2.4L engine are Interim Tier 4 and Stage III A compliant. PowerTech E engines offer a new electronically controlled unit pump fuel system with improved cold-start performance, precise engine speed control, torque curve shaping and more. These engines feature full-authority electronic engine controls, 2-valve cylinder heads, fixed-geometry turbochargers, self-adjusting poly-vee fan drives, 500-hour oil change intervals and air-to-air-aftercooled aspiration.
“With our PowerTech M and PowerTech E engines below 56 kW (74 hp), we chose to go straight from Tier 2 to Interim Tier 4,” said Doug Laudick, manager of product planning for JDPS. “Because our 2.4L engines demonstrated Interim Tier 4 and Stage III A capabilities well before our 2008 deadline, this shows that the technology we have developed is a great foundation for our Tier 4 solution.”
Information about the full line of JDPS engines and drivetrain components is available online at www.JohnDeere.com/jdpower.
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