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As a result of environmental pressures and end-user demands many manufacturers are working on fuel injection systems for the small engines market [reference 1, 2, 3, 4, 5]. A common approach is to take an automotive or motorcycle system and work to reduce its cost and complexity. This paper will present an engine management system designed from the outset specifically for low cost small engines. The key topics covered in this paper are sensor selection & minimisation, practical application of electronic throttle & ignition, power consumption minimisation and discussion of the software control strategy. In conclusion, this paper shows that most components required for a small engine management system can be integrated into a throttle body requiring only 3 external components. It is also possible, with the addition of electronic throttle and ignition, to deliver significant user enhancements.

Two methods have been achieved of facilitating controlled auto-ignition (CAI) combustion in a 4-stroke engine. This has been accomplished without the need to pre-heat intake air and was made possible through the use of the Active Valve Train (AVT) system. AVT was used to vary the amount of trapped exhaust gasses (otherwise known as exhaust residuals) inside the cylinder prior to the compression stroke. Both methods represent examples of internal exhaust gas recirculation (EGR). It was observed that the amount of internal EGR determined the combustion initiation point as a function of crank angle, thus demonstrating that both methods are controllable reproducible processes. Initial results (taken at 2000rpm and 3.5bar IMEP) show that this combustion significantly reduces NOx emissions to ultra-low levels compared to conventional spark ignition combustion. Data presented here represents the first published results of our internal EGR methodologies.

Controlled auto ignition (CAI) is a form of combustion which uses an auto-ignited homogeneous air/fuel mixture but is controlled (or moderated) by regulating the quantity of internal exhaust gas residuals. In this paper, using a fully variable valve train and a newly developed exhaust valve control strategy, we substituted EGR with hot nitrogen or hot air. We found that the internal exhaust gas residuals have both thermal and chemical effects on CAI combustion. To investigate the thermal effect, nitrogen was used as it is a chemically inert gas. Although its temperature was raised to that of the internal exhaust gas residuals during testing, CAI combustion could not be promoted without assistance from a spark in a form of hybrid CAI, thus indicating that exhaust gas residuals have a chemical effect as well.

Recently [SAE 2001-01-0251], we reported for the first time on using a fully variable valve train (FVVT) to facilitate controlled auto-ignition (CAI) in 4-stroke gasoline engines, with a 23% reduction in fuel consumption and a reduction of up to 95% in emission levels. In this paper we look at the industry trends towards increased control over combustion related processes occurring in modern engines, which signaled the direction towards the CAI work, and review a range of valve train technologies available to meet these trends. Previous key work conducted by industry and academic researchers is also reviewed to establish a minimum specification requirement for the new fully variable valve train systems. The paper then describes two electro-hydraulic valve actuation systems capable of meeting these specifications, the first a research grade system used on single cylinder engines and the second a new production viable system that is aimed at bringing FVVT's to high volume production.

The purpose of the ELEVATE (European Low Emission V4 Automotive Two-stroke Engine) industrial research project is to develop a small, compact, light weight, high torque and highly efficient clean gasoline 2-stroke engine of 120 kW which could industrially replace the relatively big existing automotive spark ignition or diesel 4-stroke engine used in the top of the mid size or in the large size vehicles, including the minivan vehicles used for multi people and family transportation. This new gasoline direct injection engine concept is based on the combined implementation on a 4-stroke bottom end of several 2-stroke engine innovative technologies such as the IAPAC compressed air assisted direct fuel injection, the CAI (Controlled Auto-Ignition) combustion process, the D2SC (Dual Delivery Screw SuperCharger) for both low pressure engine scavenging and higher pressure IAPAC air assisted DI and the ETV (Exhaust charge Trapping Valve).