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This paper details the development of a new dynamic Intake Air Simulator (IAS) for use on single-cylinder test engines, where the gas dynamics are controlled to accurately simulate those on a multi-cylinder engine during transient or steady-state operation. The third generation of Intake Air Simulators (IAS3) continues a development of new technology in the Powertrain Control Research Laboratory (PCRL) that replicates the multi-cylinder engine instantaneous intake gas dynamics on the single-cylinder engine, as well as the control of other boundary conditions. This is accomplished by exactly replicating the intake runner geometry between the plenum and the engine intake valve, and dynamically controlling the instantaneous plenum pressure feeding that runner, to replicate the instantaneous multi-cylinder engine intake flow.

Researchers at the Powertrain Control Research Laboratory (PCRL) at the University of Wisconsin-Madison have developed a transient test system for single-cylinder engines that accurately replicates the dynamics of a multi-cylinder engine. The overall system can perform very rapid transients in excess of 10,000 rpm/second, and also replicates the rotational dynamics, intake gas dynamics, and heat transfer dynamics of a multi-cylinder engine. Testing results using this system accurately represent what would be found in the multi-cylinder engine counterpart. Therefore, engine developments can be refined to a much greater degree at lower cost, and these changes directly incorporated in the multi-cylinder engine with minimal modification. More importantly, various standardized emission tests such as the cold-start, FTP or ETC, can be run on this single-cylinder engine.

The demand for transient dynamometer testing systems is on the rise in the automotive industry. A useful power transmitting device for these systems is a hydraulic pump/motor due to its extremely low-inertia and minimal maintenance requirements. For a high-speed hydrostatic dynamometer system to be commercially acceptable, a pump/motor capable of speeds in excess of 8,000 RPM must be available with appropriate power capacity. Current industrial solutions offer speeds up to 3,000 RPM and 5,500 RPM respectively for external gear and piston pump designs and are therefore unsuitable for testing the upper speed ranges of numerous currently produced automotive engines. In this study, the effects of various pump housing, thrust plate and gear designs are examined utilizing Simerics’ PumpLinx pump/motor specific CFD software.

To serve the increasing demand of the automotive industry for transient systems evaluation, the Powertrain Control Research Laboratory (PCRL) has developed a transient test facility which uses high-bandwidth hydraulic dynamometers for hardware-in-the-loop powertrain simulation and testing. Following building renovation in 2006, the research team assumed the task of reconfiguring the dynamometer laboratory into a state-of-the-art testing facility. This includes the relocation and design of support facilities for both single- and multi-cylinder engine transient test systems. This paper introduces the applications of transient testing facilities and describes the unique challenges faced by the research team to achieve a versatile powertrain research environment with emphasis on accessibility and optimal space utilization, maintainability, and comprehensive documentation to aid future research endeavors.

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.

Developing dynamic models of internal combustion engines can be very challenging because of the broad range of components that comprise the engine, as well as the range of engineering disciplines that are brought to bear in the design. The task is further complicated because the goals of such a model can vary immensely depending upon its use, and in a high-quality dynamic model these goals will drive the overall structure and fidelity of the model. Note that the quality or usefulness of the dynamic model is independent of its fidelity. This paper presents a generalized modular engine modeling structure, developed using MathWorks' MATLAB/Simulink software, which can be used in developing dynamic models of internal combustion engines or other dynamic powertrain models. The generalized block is discussed in detail, and specific applications of this block are shown within an overall engine model.

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.

This paper reviews the engine modeling program in the Powertrain Control Research Laboratory at the University of Wisconsin-Madison, focuses on simulation results obtained from a complete modular turbocharged diesel engine dynamic model developed in this lab, and suggests ways that dynamic engine system models can be used in the design process. It examines the dynamic responses and interactions between various components in the engine system, looks at how these components affect the overall performance of the system in transient and steady state operation.

This Paper introduces a modular, flexible and user-friendly dynamic powertrain model of the US Army's High Mobility Multi-Wheeled Vehicle (HMMWV). It includes the DDC 6.5L diesel engine, Hydra-matic 4L80-E automatic transmission, Torsen differentials, transfer case, and flexible drive and axle shafts. This model is used in a case study on transmission optimization design to demonstrate an application of the model. This study shows how combined optimization of the transmission hardware (clutch capacity) and control strategy (shift time) can be explored, and how the models can help the designer understand dynamic interactions as well as provide useful design guidance early in the system design phase.

Simulation is a useful tool which can significantly reduce resources invested during product development. Vehicle manufacturers are using simulations to aid in the evaluation of designs and components, including powertrain systems and controllers. These simulations can be made more useful by addressing issues such as flexibility, modularity, and causality. These issues and other aspects involved in the development and use of powertrain system simulations are discussed in this paper, and a case study of a powertrain system model developed in the PCRL using methodologies based on considerations of such issues is presented.

Transient operation of automobile engines is known to contribute significantly to regulated exhaust emissions, and is also an area of drivability concerns. Furthermore, many on-board diagnostic algorithms do not perform well during transient operation and are often temporarily disabled to avoid problems. The inability to quickly and repeatedly test engines during transient conditions in a laboratory setting limits researchers and development engineers ability to produce more effective and robust algorithms to lower vehicle emissions. To meet this need, members of the Powertrain Control Research Laboratory (PCRL) at the University of Wisconsin-Madison have developed a high-bandwidth, hydrostatic dynamometer system that will enable researchers to explore transient characteristics of engines and powertrains in the laboratory.

A hydrostatic dynamometer capable of accurately controlling the speed and torque of an engine has been designed and constructed. The thrust of this work is not only to build a better dynamometer, it is the first step in creating a system for laboratory simulation of the actual load environment of engines and powertrains. This paper presents the design, construction, and evaluation of a hydrostatic dynamometer. The evaluation includes speed and torque limits, and bandwidth of the dynamometer. Also, the dynamometer is compared with those in common use, and the feasibility of accurately reproducing the engine or powertrain load environments are assessed. This is the first phase of a development program; future research is discussed.