Fuel economy without the need for low sulphur fuel

Orbital’s direct injection system combined with Johnson Matthey’s catalyst technology looks set to reduce the cost and risk of applying direct fuel injection to automobiles.

Orbital Engine Corporation’s direct injection system combined with Johnson Matthey’s catalyst technology looks set to reduce the cost and risk of applying direct fuel injection to automobiles.

A test vehicle featuring the Orbital Combustion Process (OCP) direct injection system achieved a 12% fuel economy improvement (over the PFI baseline vehicle) and Euro 4 emissions standards with a specially developed Johnson Matthey 3-way catalyst. The test results were achieved in a standard 4-door sedan powered by a 2.0 litre, 16-valve, 4-stroke engine running the latest iteration of the OCP direct injection system.

The emissions control system, developed in conjunction with Johnson Matthey, incorporates advanced 3-way catalyst technology, which is not reliant on ultra low sulphur fuel to meet these tight limits. To verify the durability of the system, the catalyst was severely hydrothermally aged by Johnson Matthey at temperatures up to 1050°C.

Director of Orbital’s Automotive group Dr. Rod Houston described the latest test results as a significant step forward in proving the suitability of OCP technology for global applications in the near term.

‘Alternative direct injection systems have been reliant on lean NOx trap systems, to achieve their emissions targets. The durability of these systems in real world driving conditions has not been fully proven, especially in the United States where the sulphur content in the fuel mitigates against their use.’

‘A key characteristic of Orbital’s lean-burn combustion system is the very low raw emissions of hydrocarbons (HC) and oxides of nitrogen (NOx) under stratified conditions. In addition, Orbital has developed new intellectual property to optimise the interaction of the combustion system and the after-treatment system. These test results demonstrate that OCP direct injection could be applicable in regions such as the United States, where the sulphur content of the fuel prohibits the use of NOx trap systems.’

Dr. Martyn Twigg, European Technical Director of Johnson Matthey stated; ‘This is an excellent result which allows fuel economy to be gained without the need for the ultra low sulphur fuel necessary with NOx trap systems. Vehicles equipped with NOx traps and running on appropriate low sulphur fuel demonstrate significant improvements in fuel economy. This result demonstrates a good interim strategy to lower CO2 emissions through improved fuel economy until low sulphur fuel is widely available.’

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