Direct injection

A consortium from industry and academia has launched a research programme that will investigate an innovative approach to managing a gasoline direct injection engine.

The so-called HOTFIRE consortium is made up of Lotus Engineering, Siemens VDO Automotive, Loughborough University and University College London. Lotus Engineering is managing the consortium which aims to achieve better performance, lower emissions, and improved fuel efficiency from a gasoline direct injection engine.

The HOTFIRE consortium (Homogeneous and Throttleless for Fuel efficiency with Reduced Emissions) is part-funded by the UK Engineering and Physical Sciences Research Council (EPSRC).

Gasoline direct injection is seen as critical to meeting future legislative and market requirements for greater fuel efficiency. Current gasoline direct injection engines operate in two modes. The ‘homogeneous’ mode gives superior performance when higher outputs are required, while lean burn or ‘stratified’ mode delivers more economical fuel consumption at part load through reduced throttling losses.

Despite offering fuel savings, lean burn does not allow proven three-way catalyst technology to be used, forcing manufacturers to fit deNOx catalysts and particulate traps, adding to vehicle costs. Such additional costs have in part been responsible for the slow growth of sales in gasoline direct injection vehicles because the first generation of stratified charge engines did not achieve the fuel savings needed to justify the add-on cost.

As a result, the HOTFIRE consortium sees two options emerging in the future.First, a second generation stratified (spray-guided) concept delivering greater fuel savings justifying the add-on cost of the deNOx system. And second, a homogeneous charge direct injection strategy offering a reduced fuel saving potential for lower system cost. It is this approach that the HOTFIRE programme is exploring.

The HOTFIRE consortium will investigate a new concept for managing the combustion in the chamber. “This research programme will examine engines running permanently in homogenous mode while also eliminating throttling losses by using Lotus’ AVT fully variable valve train to control the intake of air,” explained Ian Watson, Chief Powertrain Engineer at Lotus Engineering.

“With greater control of engine variables afforded by Lotus’ AVT system, there is potential for remarkable strides to be made in maximising the full capability of the internal combustion engine.”

As well as managing the research programme, Lotus Engineering is supplying two single cylinder research engines, one of which has optical access (SCORE) and is fitted with the company’s Research AVT fully variable valve train. Siemens VDO is supplying the direct injection equipment.

The research engines will be run at two UK Universities. Loughborough University will run the optical research engine in conjunction with its impressive laser diagnostics facility to gain a comprehensive understanding of the in-cylinder phenomena. The second single cylinder research engine will run at University College London (UCL) to measure the thermodynamic properties in terms of power and emissions.

“HOTFIRE brings together a formidable depth of world-leading experience and knowledge to address the very real issues facing global vehicle manufacturers: how to achieve increased fuel economy and reduced emissions with acceptable system cost. Together we are confident that progress can be made to develop a leading technology that is commercially viable before the end of the decade,” said Dr. Hans Nuglisch from Siemens VDO.

The HOTFIRE project is scheduled for completion in September 2007, with a PhD student at each university undertaking the research. The consortium is receiving almost £500,000 funding from the EPRSC, with additional funding from Lotus and Siemens VDO taking the total research budget to around £1 million.

The programme is expected to generate further spin-off collaborative projects, and Lotus Engineering and Siemens VDO hope to realise a commercial advantage from the HOTFIRE programme within five years.