/ Emissions Technologies
A long history of environmental responsibility
John Deere takes its responsibility to the environment very seriously. We have been working on reducing engine emissions since 1967, when John Deere first installed emissions testing equipment — years before governments recognized the need for emissions regulations. John Deere also actively worked with industry partners such as the Engine Manufacturers Association (EMA), the European Association of Internal Combustion Engine Manufacturers (EUROMOT), and regulatory agencies worldwide to advance environmental initiatives.
In our efforts to reduce engine emissions and fuel consumption, John Deere engineers employ a global network of technical resources. Today, we utilize the latest technology for lowering nitrogen oxides (NOx), particulate matter (PM), carbon monoxide (CO), hydrocarbons (HC), and carbon dioxide (CO2) emissions — all while improving fuel efficiency.
These efforts result in engines that meet or surpass nonroad emissions regulations for the U.S. Environmental Protection Agency (EPA), California Air Resource Board (CARB), the European Union (EU), and other regulated regions. We launched all of our previous engines ahead of EPA and EU deadlines, and plan to do the same for Interim Tier 4/Stage III B engines. And we are accomplishing it while maximizing fuel efficiency and engine performance.
The non-road industry has made significant gains in its efforts to reduce emissions and improve performance. Currently, less than 0.3 percent of non-road engine exhaust contains emissions pollutants like NOx, CO, HC, and PM. The rest (99.7 percent) of engine exhaust is made up of natural elements in the air like nitrogen (N2), oxygen (O2), and water vapor (H2O). Throughout the same period, power output from our engines has steadily increased.
Charge air cooling
Keeping air intake temperatures as low as possible controls NOx. John Deere leads the industry in applying air-to-air charge air cooling to nonroad applications. This technology has been used on John Deere engines for nearly 20 years. Air-to-air charge air cooling not only reduces NOx, it improves engine durability and increases low-speed torque and power density. It is the most efficient method of cooling intake air to help reduce engine emissions while maintaining low-speed torque, transient response time, and peak torque. Charge air cooling enables an engine to meet emissions regulations with better fuel economy and lower installed costs.
Exhaust gas recirculation (EGR)
The lower an engine’s peak combustion temperature, the less the amount of NOx created. EGR is an effective method of reducing peak combustion temperature, thereby reducing NOx. The concept is simple. During certain conditions of engine operation, the EGR valve opens and controlled amounts of exhaust gas are routed back into the intake manifold and mixed with the incoming fresh air. Since this process removes some oxygen from the air, the exhaust temperatures in the combustion process are lowered and the levels of NOx are reduced.
Cooled EGR, as used in John Deere PowerTech Plus engines, increases the effectiveness of NOx reduction, while enhancing engine efficiency and power density (similar to charge air cooling).
Fixed geometry turbocharger
Fixed geometry turbochargers are precisely matched to power level and application. Transient smoke is controlled by using higher-boost turbochargers which increase low-speed torque and prevent over-boosting at high speed. Variable geometry turbocharger (VGT)
Another key feature of John Deere PowerTech Plus engines is the VGT, which tailors the amount of cooled recirculated exhaust gas that mixes with the fresh air. This tailoring is accomplished by the engine control unit (ECU), which changes the pitch of the VGT vanes in order to maximize power and efficiency. The amount of cooled EGR required is determined by load and engine speed. When exhaust flow is low, the vanes are partially closed. This partial closure increases the pressure against the turbine blades, making the turbine spin faster and generating more boost. Series turbocharging
One of the methods to reduce NOx emissions is to increase EGR rates. This in turn requires increased intake air pressure. Series turbocharging is an effective means for supplying this increased intake air.
In series turbocharging, filtered ambient air is drawn into the first turbocharger compressor stage. The pressurized air is then passed to the second turbocharger compressor stage after which it is cooled and then introduced into the intake manifold. The two compressor stages enable much higher intake air pressure than what is capable with a single turbocharger. Also, using two turbochargers broadens the operating range of the engine.
Diesel exhaust filters
Diesel oxidation catalyst (DOC)
The diesel oxidation catalyst (DOC) is effective at reducing carbon monoxide, hydrocarbon, and some particulate matter (PM). This flow-through catalyst oxidizes both gaseous (volatile) hydrocarbons and the portion of PM known as the volatile organic fraction (VOF). At higher exhaust temperatures, DOCs can also oxidize sulfur to form sulfate PM. Catalyst manufacturers have been able to achieve the needed VOF reduction while minimizing sulfate formation.
DOCs typically reduce emissions of carbon monoxide by 40 percent, hydrocarbons by 50 percent, and PM by 20 percent. Diesel particulate filter (DPF)
DPFs play an important role to meet emissions regulations for Interim Tier 4/Stage III B and Final Tier 4/Stage IV. The questions that OEMs want answered are: “How much will they cost?” “What size will they be?” “How long will they last before servicing is needed?” Manufacturers are working hard to reduce the cost and optimize the size of these exhaust filters.
The DPF traps and holds particulates from the exhaust. Exhaust gas flows through channels with porous walls that allow exhaust to escape, but traps soot and particulates. One challenge is to ensure regeneration, or cleaning, under all operating conditions.