EMISSIONS & IT4


EMISSIONS AND TIER 4


37 percent compared to Tier 2. To meet the Tier 3 regulations for machines between 75 and 100 horsepower, Bobcat implemented a cooled exhaust gas recirculation (CEGR) process. Additional components were added to help Bobcat meet the regulations.


Interim Tier 4 and Final Tier 4


These are the fi nal steps the EPA is implementing as part of its nonroad diesel rules to curb emissions. Deadlines needed for compliance vary the most among the tiers at this point. They began in 2008 and


CEGR: Cooled exhaust gas recirculation takes some of the diesel engine’s exhaust, cools it to a lower temperature and sends the cooled exhaust back to the engine cylinders. This cooled exhaust takes up some of the space that air normally would consume. Since the exhaust gases have already combusted, they don’t burn again when new combustion takes place. Doing this chemically slows combustion and cools it by several hundred degrees, reducing the formation of NOx


.


Particulate Matter (PM): Partially composed of leftover fuel that didn’t get burned during combustion in the diesel engine. Simply put, it’s the black soot you see emitting from a machine’s exhaust stack.


Nitrogen Oxides (NOx ):


Atmospheric pollutants produced in combustion that are invisible, but help form smog. They typically cause the most pollution.


6 WORKSAVER BobCatalog 2011


will continue through 2015 when the Final Tier 4 regulations are complete.


The good news is that many Bobcat machines are already Interim Tier 4 (25-75 hp) or Final Tier 4 (under 25 hp) compliant. This is the case with Bobcat machines with engines that are less than 75 horsepower because the emission standards were less stringent. These machines have particulate matter reductions of 50 percent and comply with the low-sulfur and ultra- low sulfur diesel fuel requirements. Bobcat machines with diesel engines that have horsepower ranges between 75 and 100 will not become Interim Tier 4 compliant until 2012 and Final Tier 4 compliant until 2015.


PART3


Interim Tier 4 and Tier 4 Technologies


Now that we’ve looked at the history of the EPA emission standards, it’s time to review the technologies available to manufacturers to reach iT4/T4 compliance. This is a comprehensive list of the available technologies, at a high level, and not necessarily how Bobcat equipment will reach iT4/T4 compliance.


Engine manufacturers identifi ed the fuel injection system as a major focus point to help meet the EPA nonroad diesel engine emission levels for iT4/T4. Fuel injection systems affect the diesel engine’s fuel consumption, torque, noise and emission levels.


High-Pressure Common-Rail Fuel System (HPCR) The fuel injection system is a major


area of focus for advancement toward clean-operating diesel engines. HPCR is an advanced fuel-injection design that


regulates fuel pressure and injection timing. The HPCR regulates how and when fuel is injected into the engine. First, it takes fuel and applies high amounts of pressure to it (22,000 to 34,000 psi). The rail stores the high pressure fuel and delivers it to the injectors.


Fuel pressure • The pump applies extreme pressure to fuel (22,000 to 34,000 psi).


• The common rail stores pressurized fuel. • The injectors deliver fuel to the engine.


Injection timing The electronic control unit (ECU) precisely controls injector to allow multiple fuel injections during each combustion cycle.


HPCR benefi ts Extreme pressure transforms fuel into extremely fi ne mist as it leaves the injectors. Fuel mist combusts (burns) more thoroughly.


1. Lower operating costs: When fuel combusts more thoroughly, less is needed to make the engine run. The result is improved fuel economy.


2. Cleaner exhaust: When fuel combusts more thoroughly, less of it is left over in the exhaust after combustion. The result is cleaner exhaust.


When fuel is injected multiple times during each combustion cycle, the combustion lasts longer to create more energy and lower peak engine cylinder pressure:


3. Better performance: Creating more energy during combustion results in more torque output from the engine.


4. More operator comfort: Lower peak engine cylinder pressure reduces engine noise levels.


High-pressure common-rail fuel system (HPCR)


Fuel


Pressure Pump


Fuel Tank


Pressure Fuel


High


Electronic Control Unit


High


Common Rail


InjectorInjectorInjectorInjector


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