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Technical Paper

Feasibility of Multiple Piston Motion Control Approaches in a Free Piston Engine Generator

The design optimization and control of Free Piston Linear Engine (FPLE) has been found to be difficult as each independent variable changes the dynamics with respect to time. These dynamics, in turn, alters the alternator and engine response to other governing variables. As a result, the FPLE system necessitates an energy balance control algorithm with high-speed dynamic response for stable operation and perhaps optimized system efficiency. The main objective of this control algorithm is to match the power generated by the engine to the power demanded by the alternator. This energy balance control is similar to the use of a governor to control the crankshaft rotational speed in a conventional crankshaft driven engine. In addition to that, when stiff springs are added to the FPLE system, the dynamics becomes more sinusoidal and more consistent with increasing spring stiffness.
Technical Paper

An Approach to Simulate Chassis Dynamometer Test Cycles with Engine Dynamometer Test Cycles for Heavy-Duty Urban Buses

A mathematical model has been developed to transfer Chassis Dynamometer (CD) test cycles for heavy duty vehicles to the equivalent Engine Dynamometer (ED) test cycles. The model assumed a generalized drivetrain layout, and a variable drive line efficiency. An interactive computer code was written to represent the mathematical model for different drivetrain systems. Several CD test cycles were used to obtain equivalent ED test cycles for a sample based upon an urban bus equipped with an automatic transmission. Results showed the possibility of simulating CD test cycles with equivalent ED test cycles for heavy-duty urban buses under certain assumptions.
Technical Paper

Measurement Delays and Modal Analysis for a Heavy Duty Transportable Emissions Testing Laboratory

Concern over atmospheric pollution has led to the development of testing procedures to evaluate the hydrocarbon, carbon dioxide, carbon monoxide and oxides of nitrogen emissions from internal combustion engines. In order to perform emissions testing on vehicles, a chassis dynamometer capable of simulating expected driving conditions must be employed. West Virginia University has developed a Heavy Duty Transportable Emissions Testing Laboratory to perform chassis testing on trucks and buses. Emissions from the vehicle are monitored and recorded over the duration of a testing schedule. Usually the vehicle emissions from the whole test are reported as mass of emissions per unit distance driven. However, there is interest in relating the instantaneous emissions to the immediate conditions at specific points in the test, and in determining the emissions for discrete segments of the test (modal analysis).