In October, Bobcat became the latest manufacturer to announce a Tier 4 solution that eliminates the need for a diesel particulate filter (DPF). As part of its strategy, Bobcat will move away from its current engine supplier and instead utilize engines built by parent company Doosan in select equipment for 2014.
Development of the new Tier 4-compliant engine is a collaboration between Bobcat, Doosan and such top engineering consultants and engine design firms as Ricardo and FEV, among others. The Doosan-built engine will include three models with 1.8L to 3.4L displacements and 33 to 99 hp. The engines will not require a diesel particulate filter to achieve Tier 4 compliance. They will be available in select Bobcat machines meeting Tier 4 horsepower requirement ranges sometime in early 2014.
While Bobcat and Doosan are not yet prepared to release details of the technology behind the engines, several other engine suppliers have already made their solutions public. Following is a synopsis of their designs for 2014 and beyond.
Two Key Suppliers Join Forces
In the fall of 2011, Kohler Engines and Lombardini came together to unveil the Kohler KDI1903TCR and KDI2504TCR heavy-duty diesel engines, which achieve Tier 4 Final emissions compliance minus the DPF. This was made possible by combining such components as Kohler’s direct injection system, cooled exhaust gas recirculation (EGR) and a diesel oxygenated catalyst (DOC).
High-pressure common rail fuel injection was a big contributor to the new engine design. Kohler centrally located the fuel injector within a four-valve head and optimized the injector nozzles and spray pattern. The result is a high-pressure system that utilizes pressures at 29,000 psi, resulting in better atomization of the fuel, improved fuel consumption and a reduction in emission particulates.
An electronic control unit (ECU) drives the fuel injection system. The mapping program within the ECU monitors and manages power output in varying conditions by injecting fuel multiple times into the combustion cycle to maximize torque and power when needed most.
According to Kohler, the direct injection system provides the ability to save up to $1,400 on fuel and $116 on oil per year compared to indirect injection diesel engines with diesel particulate filters. This is based on 1,000 hours of annual operation at $3.75 per gallon of diesel fuel and $4.10 per quart of oil.
The engines continue to deliver sufficient power for a variety of industrial, construction and agricultural applications. The 1.9-liter KDI1903TCR supplies 56 hp at 2,600 rpm and 166 ft.-lbs. of torque at 1,500 rpm. The 2.5-liter KDI2504TCR has a power density of 74.3 hp at 2,600 rpm and 221.3 ft.-lbs. of torque at 1,500 rpm. Other features include less noise and vibration, as well as a heavy-duty crankcase for increased durability to extend engine life.
No DPF for Under 750-hp Engines
At MINExpo 2012 , the Tognum Group, a global supplier of engines and propulsion systems and distributed power generation systems, showcased its MTU-brand C&I engines designed to meet Tier 4 Final emissions regulations.
The Series 1000, 1100, 1300 and 1500 engines will use selective catalytic reduction (SCR) exhaust aftertreatment technology to achieve compliance with limits set for nitrogen oxides (NOx) and particulate emissions. No DPF is required to achieve further particulate reduction.
The new engines will cover the 750-hp and below power range, offering outputs ranging from 134 to 617 hp. According to Tognum, they will provide up to 5% reductions in fuel consumption, up to a 20% increase in service life, higher torque at low engine speeds, greater engine brake power and fast, straightforward maintenance.
Series 1600 C&I engines — which meet Tier 4 Final regulations without either SCR systems or DPFs — will be introduced to extend the range to 980 hp. The engines will incorporate in-cylinder technology, along with high-pressure common rail injection, two-stage turbocharging and cooled EGR. Particular emphasis has been placed on optimizing the combustion process in order to minimize fuel consumption.