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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.

Powertrain simulation is becoming an increasingly valuable tool to evaluate new technologies proposed for future military vehicles. The powertrain of the M1A1 Abrams tank is currently being modeled in the Powertrain Control Research Laboratory (PCRL) at the University of Wisconsin-Madison. This powertrain model is to be integrated with other component models in an effort to produce a high fidelity simulation of the entire vehicle.

An ongoing goal of the Powertrain Control Research Laboratory (PCRL) at the University of Wisconsin-Madison has been to expand and improve the ability of the single cylinder internal combustion research engine to represent its multi-cylinder engine counterpart. To date, the PCRL single cylinder engine test system is able to replicate both the rotational dynamics (SAE #2004-01-0305) and intake manifold dynamics (SAE #2006-01-1074) of a multi cylinder engine using a single cylinder research engine. Another area of interest is the replication of multi-cylinder engine cold start emissions data with a single-cylinder engine test system. For this replication to occur, the single-cylinder engine must experience heat transfer to the engine coolant as if it were part of a multi-cylinder engine, in addition to the other multi-cylinder engine transient effects.

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.

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.

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 presents details of the development of, and experimental results from, an internal combustion engine dynamic cylinder heat transfer control device for use on single-cylinder research engines. This device replicates the varying temperature profile and heat transfer distribution circumferentially around a cylinder in a multicylinder engine. This circumferential temperature distribution varies around a cylinder because of the location of, or lack of coolant passages around the cylinders, and varies from cylinder to cylinder as a result of the flow of the coolant through these passages as it accumulates thermal energy and increases in temperature. This temperature distribution is important because it directly affects the NO emissions from each cylinder, as will be seen in the experimental results.

A new method for instantaneous friction estimation in firing internal combustion engines has been developed in the Powertrain Control Research Laboratory (PCRL) at the University of Wisconsin - Madison. This Synthetic Variable approach, which has previously been used for combustion quality diagnostics, focuses on carefully measuring instantaneous engine speed and other easily measurable engine variables and combining them with dynamic models of other engine processes. This approach numerically strips away the dynamic effects that mask friction effects on engine speed and reveals friction estimates with clarity. This information could be useful for engine designers and developers to assist in accurately understanding the sources of instantaneous friction within the running engine. The friction results from these studies have been very encouraging.

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 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.

Brake systems in current production automobiles are the result of a long evolutionary process beginning with the first practical hydraulic brake patent in 1917. While the basic hydraulic design has many advantages, recent modifications to this system for anti-lock braking and traction control considerably increase the cost of manufacture. As a result, many manufacturers are investigating the possibility of developing alternate braking system structures that cost less and can easily interface with vehicle electronics. Evaluating these systems for fault tolerance and failure effects is crucial to provide a safe and reliable vehicle braking system. This paper demonstrates the use of the Fault Tree Analysis method for carrying out such an evaluation. An example system is presented to illustrate the application of this method to automobile brake design.

This paper investigates the dynamic errors between the commonly used two-lump mass connecting rod model and the actual connecting rod model for the internal combustion engine. Because of the errors between the actual rod inertia and this simplified two-lump mass model, incorrect engine dynamics and internal forces are often predicted. In this paper, the magnitudes of force differences related to errors of connecting rod inertia are presented for various engines at different engine operating speeds. A method to predict the maximum side force and its maximum deviation is presented. And the technique to minimize variability in connecting rod mass and moment of inertia, as well as minimizing errors in the lumped mass model commonly used in industry are also introduced to avoid incorrect engine dynamics and internal forces.

Many researchers have studied and developed methods for on-board engine combustion misfire detection in production vehicles. Misfiring can damage the catalytic converter within a short time and can lead to increased emission levels. For that reason, the on-board detection of engine misfire is one requirement of the On Board Diagnosis II (OBDII) Regulation and a recent interest for many researchers. One object in this paper is to propose a misfire detection method for multi-cylinder SI engines. The detection is achieved by examining the estimated cylinder pressures and combustion heat release rates in engine cylinders. The Sliding Observer methodology is applied in these estimations. This detection method provides a reliable and low-cost way to diagnose engine misfires. The other object of the paper is to eliminate large estimation errors due to system unobservability and reconstruct cylinder pressures.

Nonlinear observer theories are applied to the engine estimation problem in order to reconstruct engine states based on the measured engine variables, and dynamic mean torque production and cylinder-by-cylinder engine models. Engine cylinder and intake manifold pressures are two important factors in engine control and diagnostics. This paper discusses how to design nonlinear engine cylinder pressure and intake manifold pressure observers that have good robustness and estimation accuracy. Sliding mode theory in Variable Structure Systems (VSS) have shown good performance and been successfully applied to many nonlinear systems. Accordingly, sliding observers are selected for this study.

Stoichiometric air-fuel ratio control during transient operation requires an accurate estimate or measurement of the instantaneous air flow rate in an engine. Two methods are commonly used for determining engine air flow rate: air-mass sensing and conventional “speed-density.” The lead air flow information provided by air-mass sensors helps compensate for manifold filling and other fuel system delays. However, the high cost (and sometimes lower reliability) of air-mass sensors has led many manufacturers to continue to use the less accurate speed-density method for determining air flow rate. This paper develops a model-based nonlinear manifold pressure observer that estimates the flow rates at the throttle and the intake ports of an engine using speed-density type sensors. The throttle flow rate estimate can be used instead of an air-mass sensor to provide the lead information necessary for accurate transient air-fuel control on TBI engines.

A transmission system model for Ford Motor Company's automatic transmission (AOD) system used in the Lincoln Town Car has been developed using the free-body diagram method (Newtonian approach). This model is sophisticated enough to represent the dynamic behavior of the transmission system, yet simple enough to use as a real time computer simulation tool, and as an embedded model within a dynamic observer. The transmission system and torque converter models presented in this paper are part of a larger powertrain system model at the Powertrain Control Research Laboratory, University of Wisconsin-Madison.

The use of graphical dynamic system simulation software is becoming more popular as automotive engineers strive to reduce the time to develop new control systems. The use of model-based control methods designed to meet future emission and diagnostic regulations has also increased the need for validated engine models. A previously validated, nonlinear, mean-torque predictive engine model* is converted to MATLAB / SIMULINK† to illustrate the benefits of a graphical simulation environment. The model simulates a port-fuel-injected, spark-ignition engine and includes air, fuel and EGR dynamics in the intake manifold as well as the process delays inherent in a four-stroke cycle engine.

A nonlinear model-based method for engine misfire detection has been proposed in the earlier work [2]. Many possible reasons for persistent cylinder misfire (e.g., a burned inlet valve or other faults), however, still need to be identified. Identification of engine misfire enables engineers, vehicle operators or technicians to trace the cause of misfire and to identify the faulty components in the engine. Also, a cylinder-by-cylinder manifold model will provide a considerably more accurate estimate of individual cylinder air flows. This paper develops a model-based nonlinear intake manifold pressure observer and an algorithm to identify a burned inlet valve. The proposed manifold model is a runner-by-runner model. A nonlinear observer using this runner-by-runner model can estimate the plenum pressure and all individual runner pressures and their subsequent flows. The estimate is then used as an indication of a faulty inlet valve, one of the possible causes of engine misfire.