Zetor tractors are developed with a view to offer attractive design and high product manufacture qualities and last but not least to be environmentally friendly. Our company places emphasis on regardful behavior to nature not only by new product development but also in its production and subsequent operation by customers.
Europe legislation determines maximal values of harmful compounds in exhaust gas. Tighter limits are a challenge for our constructors, who are currently finalizing development of new drive units satisfying emission limits TIER IIIb taking effect from 2012.
Drive units for of road applications manufactured since 2006 have to meet emission limits TIER IIIa. It is necessary to solve a combustion process in a new way for NOx emissions abatement. The system of air supercharging and way of its cooling was changed. It was also used controlled and cooled recirculation of exhaust gases. So-called small electronization of fuel injection pump was introduced, which controls EGR valve depending up engine load and engine speed.
Experience and endurance tests show that for emission limits TIER IIIb it will be necessary to use four-valve technology of cylinder head, cooled and controlled recirculation of exhaust gases with filter of solids.
To meet emission limits TIER IV, which will be valid from 2014, it will be necessary to inject carbamide solution into exhaust emission system to markedly decrease NOx. It will be also indispensable to use controlled fuel delivery system with a pressure reservoir.
Two inlet valves and two exhaust valves enable an increase of combustion process efficiency, improve course of torque and cut fuel consumption.
Centric location of a combustion chamber causes uniform piston temperature load and correct circulation definition inside the engine combustion chamber.
Control according engine load and engine speed was already on pump for TIER IIIa. To meet TIER IIIb it is necessary to develop a pump with empowered electronic elements for better monitoring of control rod position.
The fuel injected into the engine's combustion chamber from vertically constructed fuel injection valve enable uniform fuel distribution covering in engine's combustion chamber, which leads to creation of more homogenous compound of fuel with air.
EGR valve with proportional control enables adapting recycled exhaust emissions to engine operating mode regarding abatement of NOx emissions.