A Transient Single Cylinder Test System for Engine Research and Control Development

Abstract

A transient test system was developed for a single cylinder research engine that greatly improves test accuracy by allowing the single cylinder to operate as though it were part of a multi-cylinder engine. The system contains two unique test components: a high bandwidth transient hydrostatic dynamometer, and an intake airflow simulator. The high bandwidth dynamometer is used to produce a speed trajectory for the single cylinder engine that is equivalent to that produced by a multi-cylinder engine. The dynamometer has high torque capacity and low inertia allowing it to simulate the speed ripple of a multi-cylinder engine while the single cylinder engine is firing. Hardware in loop models of the drivetrain and other components can be used to test the engine as though it were part of a complete vehicle, allowing standardized emissions tests to be run. The intake airflow simulator is a specialized intake manifold that uses solenoid air valves and a vacuum pump to draw air from the manifold plenum in a manner that simulates flow to other engine cylinders, which are not present in the single cylinder test configuration. By regulating this flow from the intake manifold, the pressure in the manifold and the flow through the induction system are nearly identical to that of the multi-cylinder application. The intake airflow simulator allows the intake runner wave dynamics to be more representative of the intended multi-cylinder application because the appropriate pressure trajectory is maintained in the intake manifold plenum throughout the engine cycle. The system is ideally suited for engine control development because an actual engine cylinder is used along with a test system capable of generating a wide range of transient test conditions. The ability to perform transient tests with a single cylinder engine may open up new areas of research exploring combustion and flow under transient conditions. The system can also be used for testing the engine under conditions such as cylinder deactivation, fuel cut-off, and engine restart. The improved rotational dynamics and improved intake manifold dynamics of the test system allow the single cylinder engine to be used for control development and emissions testing early in the engine development process. This can reduce development time and cost because it allows hardware problems to be identified before building more expensive multi-cylinder engines.