David J. Cleary

Dynamics and control of an electro-hydraulic fully flexible valve actuation system

As the internal combustion engine moves into the 21/sup st/ century, fully flexible valve actuation (FFVA) systems are being proposed as an enabling technology for advanced internal combustion engine concepts. This paper focuses on exploring the dynamics and control of an electro-hydraulic fully flexible valve actuation system. Challenges and approaches for developing variable valve actuation systems are first outlined and discussed. Dynamic model of the electro-hydraulic actuator was obtained based on experimental data. A robust repetitive controller is then designed and implemented using a dSpace system. We are able to achieve valve profile tracking errors within 140 microns for a 9.5 mm lift at engine speed up to 3000 rpm. To demonstrate the flexibility and robustness of the system, we show real-time valve-lift profiles used to explore advanced combustion technologies.

Development and Optimization of a Two-Valve Spark-Ignition Direct-Injection (SIDI) Small Block Engine

A systems approach is implemented to fully optimize the overall performance of a gasoline SIDI two-valve “small block” engine. The objective is to maximize fuel economy while achieving significant improvements in idle stability, cold-start emissions, and torque and power performance relative a baseline port-fuel-injected (PFI) engine. The scope includes the optimization of the fuel injector, piston, cylinder head, cams, in-cylinder charge motion, and the intake-manifold. The results show that the SIDI engine provides the potential to achieve 6.5% better fuel economy; a result of higher efficiency when implementing a higher geometric compression ratio and significantly better combustion performance. A multiple fuel-injection strategy is examined to provide lower HC emissions at a representative cold-start operating condition. The engine’s idle stability is improved by a factor of three; the individual contributions from a better combustion system design and from multiple fuel injections are identified. The new SIDI engine concept demonstrated significantly better wide-open-throttle (WOT) performance, including up to 10% higher torque and 6% more power when using premium fuel. This document further demonstrates the performance sensitivity to engine design variables while emphasizing the importance of using a systems approach to achieve optimized performance for the direct-injection engine technology.Copyright