To answer the challenge of EU Stage IIIB and US (EPA) Tier 4 interim legislation, Volvo Construction Equipment will adopt a combination of ‘in-cylinder’ and ‘external’ solutions to meet the emissions reductions requirements.
Not only will there be significant improvements in air quality, the results of over 100,000 hours of ‘real world’ machine reliability testing of the new technology indicates that Volvo’s Stage IIIB / Tier 4 interim-compliant Volvo diesel engines will prove to offer market-leading performance and economy of operation in terms of power capacity, engine response and fuel efficiency.
Meeting the new engine emission requirements requires a systems approach; engine changes alone are insufficient. As it is one of the few manufacturers that design and make both engine and machine, Volvo is in a strong position, one boosted by its ability to transfer its vast experience and technology from its global on-road Truck and Bus solutions. (Similar emissions requirements to Tier 4i/Stage IIIB are already in force in on-highway applications.) The new generation V-ACT (Volvo-Advanced Combustion Technology) engines feature ultra high pressure variable fuel injection systems, super efficient cooled exhaust gas recirculation (EGR), precise control of the turbochargers, powerful new EMS engine management systems and an integrated exhaust after treatment system that features a particulate filter and thermal regenerator.
At the heart of Volvo’s solution is its new generation electronically controlled diesel engines, V-ACT. As well as lower emissions, they have enhanced engine monitoring and control, and higher torque – as well as improved performance. The new units feature exhaust gas recirculation (EGR), which lowers the amount of oxygen in the combustion chamber, reducing combustion peak temperature and in doing so lowering the formation of nitrogen oxides (NOx), a key requirement of the new regulations. As Tier 4 interim engines require low sulphur fuel a new cooled EGR system has been designed that allows more exhaust recirculation than the previous uncooled generation, thereby lowering NOx further.
90% soot reduction
The reduction of particulate matter (PM) from diesel engines is another target of the latest regulations. The new Volvo system uses an advanced exhaust after treatment system that reduces particulate matter by 90% compared to the previous machine series. The filter traps the particulates and temporarily holds them until there is a sufficient build up to merit ‘regeneration’. This is effectively incinerating the particulates at temperatures above 700oC, turning them to ash using a thermal regenerator. The semi-automatic regeneration system used in the Volvo solution will help maximize the uptime of the machine. Unlike other systems, Volvo’s regeneration solution can be carried out while the machine continues working, meaning no reduction in productivity.
Fuel type is also important, as new generation machines require ultra low sulphur fuels. Such fuel is not only required by the new Stage IIIB/Tier 4 regulations, it is critical for the emission control technology to work. Using other types of fuel can result in engine damage. Consequently, ‘Ultra Low Sulphur Fuel Only’ signs will be prominently placed near the fuel inlet. Using the correct engine oil is also important, as special Ultra Diesel Engine Oil VDS-4 is required, which reduces the build up of ash in the regenerator, increasing the time between ash cleaning.
Processing the process
With such sophistication, the new generation V-ACT electronic control unit (ECU) plays a fundamental role. The new EMS version boasts a more powerful processor with the capability to support more functions than its predecessor, at higher speeds and with more control. The ECU controls the entire EGR process, managing the mix of recirculated exhaust gas and fresh air that is so crucial to reducing NOx and PM emissions, while maintaining performance and economy.
Total solution provider
The impact of the EU Stage IIIB and US (EPA) Tier 4 interim legislation cannot be underestimated. There will be a need for additional operator and technician training in order to understand the principles of the new technology, but in terms of the benefit to the environment, it is worth the effort. Lower emissions, better performance, improved operational economy and higher quality are the hallmarks of the new V-ACT generation engine systems, and represent an engineering achievement of the highest calibre.