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One of the factors preventing widespread use of Homogeneous Charge Compression Ignition or HCCI is the challenge of controlling the process under transient conditions. Current engine control technology does not have the ability to accurately control the individual cylinder states needed for consistent HCCI combustion. The material presented here is a new approach to engine control using a physics-based individual cylinder real time model to calculate the engine states and then controlling the engine with this state information. The model parameters and engine state information calculated within the engine controller can be used to calculate the required actuator positions so that the desired mass of air, fuel, and residual exhaust gas are achieved for each cylinder event. This approach offers a solution to the transient control problem that works with existing sensors and actuators.

This paper provides design, development details, and experimental data of an invention that is able to replicate the transient intake gas dynamics of a multi-cylinder engine on a single-cylinder research engine. This invention directly addresses and solves a significant problem that has persisted in the engine research and development community for over 50 years. Single-cylinder engines have many attractive attributes for use in research and development of multi-cylinder engines, due to their low cost, flexibility, and easy access for instrumentation. However, engine manufacturers continue to decrease the use of these engines in the engine development process because their dynamic and transient behaviors differ significantly from that of the multi-cylinder engine. The most significant differences are in rotational dynamics, gas exchange dynamics, and inter-cylinder dynamic coupling.

A new high-bandwidth transient test system is being developed that allows a single cylinder research engine to be tested under conditions nearly identical to those experienced by individual cylinders of a multi-cylinder engine. The system consists of two unique test components: a high bandwidth transient hydrostatic dynamometer capable of simulating the combustion and rotational dynamics of a multi-cylinder engine, and an air intake simulator that pulls air from the intake manifold plenum to simulate air induction characteristics of the multi-cylinder engine. The system makes it possible to evaluate preliminary engine control strategies and perform more detailed hardware development early in a development program when representative multi-cylinder engines may not be available. This reduces engine development time and allows the transition to multi-cylinder engine hardware to proceed with fewer design changes and less cost.

A new dynamometer system has been developed to improve the accuracy of tests that are run with a single cylinder version of a multi-cylinder engine. The dynamometer control system calculates the inertial torque and combustion torque that would normally be generated in a multi-cylinder engine. The system then applies the torque from the missing cylinders of the engine with the dynamometer. A unique high bandwidth hydraulic system is utilized to accurately apply these torque pulses. This allows the single-cylinder engine to have the identical instantaneous speed trajectory as the multi-cylinder engine, to test the single-cylinder engine at all engine speeds including very low speed operation, and to now do transient speed and load testing. Not only will this dramatically extend the capabilities of current single-cylinder engine test systems, but may open up new areas of research due to its transient testing capabilities.