Suffering fuels gladly

New and tighter European legislation came into force in October demanding reduced automotive and industrial engine emissions. How will engine designers meet them?

Whether you realised it or not, new and tighter European legislation came into force in October demanding reduced automotive and industrial engine emissions. New designs must already meet the standard while current production engines should comply to the EuroIII standard by October 2001.

Since 1992, a series of European Directives have sought to regulate emissions from new vehicles and the quality of motor fuels. Starting from the EuroI standards in the early 1990’s, each directive has progressively tightened the emission limits for new vehicles.

New vehicles on the market meet EuroIII but few are diesels, and all have catalytic converters.

Toyota’s Avensis offers 109bhp from a two-litre engine and uses around 11% less fuel than earlier models. It is also one of the few diesel engines on the market to comply with EuroIII legislation.

Chrysler has joined forces with Detroit Diesel Corporation and FEV Engine Technology to develop a 1.9-litre turbo diesel which, while designed to meet EUROIII, could also meet proposed EURO IV levels (2006). This is achieved by centrally located fuel injectors; direct injection, 4 valves per cylinder; turbo charging and a catalyst to control nitrogen oxides.

The environmental impact of powered industrial machinery is also under scrutiny. It’s only a matter of time, believes Robert Marshall of Marshall’s Industrial, before the standards imposed on the automotive industry will be applied to industrial engines.

One of the benefits of a diesel engine is the amount of power it gives from relatively low revs. Volkswagen’s AVM 1.9TDI engine is the only sub 2.0 litre industrial engine that meets EuroIII without exhaust treatments, either catalytic or a particulate filter.

The engine also meets 97/68/EC legislation for mobile machinery and appliances.

Industrial engines are designed for different operating conditions than automotive engines. For example, data maps in the engine control unit are modified to give better performance when the engine is coupled to a hydraulic pump or generator.

The AVM engine was developed to achieve EuroIII without the need for any exhaust treatment. VW’s engineers tested prototype engines with different pistons, injection pumps and turbochargers until they obtained the best power and torque curves while keeping within the emissions limits. As a bonus, both power and torque are increased compared to the AFD (AVM’s predecessor).

Although both engines look similar, the engine block on the AVM is different. The oil filter housing has been turned upside down and has a simple cartridge type oil filter that is more accessible. There is also a new valve drive system and turbo charger.

The engine’s control systems will make the biggest impact, says Robert Marshall. The control unit has 7 different data blocks (more than the AFD had) for different applications, and the addition of Can Data Bus technology allows the transfer of information between the engine and many other devices, making the end product more responsive.

Marshall’s Industrial Ltd

01491 834 666

Soot gets clean sweep

Diesel particulates are known to aggravate respiratory and cardiovascular health problems. The ultrafine carbon particles produced by diesel engines are particularly damaging because they become lodged deep inside the lungs. ‘The diesel engine is essential for transporting goods, services and people but it has one major drawback – it pollutes. Even the latest diesel engines still emit smoke under certain operating conditions and all diesel engines produce fine soot particles,’ says Dr Barry Cooper, of Diesel Emission Control Systems, Johnson Matthey.

The company used its experience of catalytic converters to create the CRT to control diesel emissions. They have devised a filter that can trap and destroy the tiny, damaging carbon particles.

Trapping the carbon is fairly simple with a porous ceramic filter consisting of a honey comb of closed tubes. This allows exhaust gases to pass through but retains the carbon. The biggest problem was how to burn off the carbon without melting the filter, because accumulated soot burns at very high temperatures.

Thinking laterally about controlled explosions gave Dr Cooper and Jim Thoss the clue they needed to try combustion in different gases. Nitrogen dioxide enabled the soot to burn at just 300°C, the typical temperature of a diesel exhaust.

The final design of the CRT was born, with a two stage process. First the exhaust gases pass through a grid impregnated with platinum, which catalyses conversion of nitrogen dioxide from nitrogen oxide and oxygen normally present in the exhaust gas. The gases and the soot then go into the ceramic trap, which retains the carbon particles while the gases flow through porous walls.