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Fri December 19, 2008 - National Edition
John Deere Power Systems (JDPS) has announced the technology solutions it will use to meet the stringent Interim Tier IV/Stage III B mobile off-highway emissions regulations for engines 174 hp (130 kW) 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 III/Stage III A requirements.
To achieve compliance with these emissions regulations, John Deere will start with its Tier III 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 IV because the EGR and DOC/DPF technology path is more proven, simpler and less costly to operate, according to John Deere.
PowerTech Plus engine models in the 130 kW (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 IV, the cylinder head, fuel system, EGR, VGT and air-to-air aftercooling systems will be updated but will be similar to Tier III configurations. The engine control unit (ECU), developed and manufactured by Phoenix International, a business unit of John Deere’s Intelligent Mobile Equipment Technologies, 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 III PowerTech Plus engine platform is the best Interim Tier IV 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 (PM). 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 IV regulations require engine manufacturers also to 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.
Experience with Cooled EGR and VGT
John Deere introduced cooled EGR and VGT technologies in off-highway applications in 2005 with the start of Tier III regulations. During Tier III, John Deere has accumulated significant operating hours with these technologies in off-highway applications and has established a proven record of reliability.
With its Tier III engines and these technologies, John Deere was able to achieve record fuel economy gains over its Tier II models. For example, the PowerTech Plus 9.0L engine set fuel economy records in a John Deere 8430 tractor during independent testing at the Nebraska Tractor Test Lab, consuming nearly 9 percent less fuel than its Tier II counterpart. The 8430 is the most fuel-efficient row-crop tractor ever tested by the Nebraska Tractor Test Lab. The Tier III PowerTech Plus 9.0L engine consumes up to 17 percent less fuel than one competitor’s comparable Tier III engine. Because John Deere Interim Tier IV engines continue to use these same technologies, the expectation is they will maintain similar fuel-economy leadership in the off-highway industry.
No Selective Catalytic Reduction
In choosing a solution for Interim Tier IV, John Deere has elected not to use SCR. An SCR system injects liquid urea into the exhaust stream to reduce NOx. While it is effective, it also requires that the vehicle or machine be fitted with a separate tank, a sophisticated urea injection system and an EPA/EU-required tamper-proof diagnostic system. Since urea freezes, heating systems for the tank and delivery lines are required. In addition, urea is not conveniently available in most parts of the world at the present time, which creates access and storage concerns. SCR may be an appropriate technology for Final Tier IV/Stage IV regulations, when the technology is more developed for off-highway applications; however, for Interim Tier IV, the EGR and DOC/DPF technology approach provides the most proven, best value product to the end-user, according to John Deere.
Below 174 hp (130 kW), Final Tier IV/Stage IV
Interim Tier IV emissions regulations for engines from 75 to 173 hp (56 to 129 kW) are effective in 2012.
“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 II and for Tier III, and we’ll likely do something similar for Interim Tier IV. What I also will say is that you are not likely to see the use of SCR on any John Deere engine for Interim Tier IV,” Piasecki said.
For Final Tier IV/Stage IV, Xinqun Gui, manager of engine technology for JDPS, said: “Technologies such as cooled EGR, VGT, DOC and DPF will likely be the foundation technologies for meeting those regulations that start in 2014. SCR may have a role. We are constantly evaluating emerging technologies for their effectiveness and for their ability to provide reliable and durable products in an off-highway setting. And as with engine configurations for previous emissions tiers, we’ll continue to tailor our Final Tier IV engine solutions to fit the variety of applications off-highway customers use them in.”
The need for John Deere to design off-highway after treatment for the upcoming regulations has been supported by the formation of a dedicated after treatment business/technology group within its Waterloo-based product engineering center. While John Deere has been conducting research on after treatment for more than 15 years, the formation of this group has provided the needed focus to not only develop and validate the technologies, but also to do all the necessary sourcing, logistics, marketing and service planning that goes along with a new technology. Throughout the process, JDPS will accumulate an immense number of hours in laboratory and field testing for its Interim Tier IV engine and after treatment designs. In 2008, John Deere will have more than 26 agricultural and construction machines in the field, testing production intent systems for the 2011 regulations.
John Deere Engines under 75 hp (56 kW) Already Interim Tier IV Compliant
Six ratings from the John Deere PowerTech M and PowerTech E engine lineups already meet Interim Tier IV 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 (56 kW) are Interim Tier IV and Stage III A compliant.
PowerTech M 2.4L engines feature 2-valve cylinder heads, fixed-geometry turbochargers, mechanical unit pump fuel systems, and 500-hour oil change intervals. PowerTech E 2.4L engines feature full-authority electronic engine controls, electronic unit pump fuel systems and air-to-air-aftercooling.
For more information, call 800/533-6446 or visit www.JohnDeere.com/jdpower.
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