Search

Look ahead information can be used to improve the powertrain’s fuel consumption while efficiently controlling exhaust emissions. A passenger car propelled by a Euro 6d capable diesel engine is studied. In the conventional approach, the diesel powertrain subsystem control is rule based. It uses no information of future load requests but is operated with the objective of low engine out exhaust emission species until the Exhaust After-Treatment System (EATS) light off has occurred, even if fuel economy is compromised greatly. Upon EATS light off, the engine is operated more fuel efficiently since the EATS system is able to treat emissions effectively. This paper presents a supervisory control structure with the intended purpose to operate the complete powertrain using a minimum of fuel while improving the robustness of exhaust emissions. A supervisory controller assisted by look ahead information, and using a supervisory control interface that works in concert with low level local controllers, can make subsystems operate near optimal. The look ahead parametrized supervisory control calculates the set-points for the subsystems: Internal Combustion Engine (ICE), Lean NOx Trap (LNT) and the Selective Catalytic Reduction (SCR) based on the Emission Equivalent Fuel Consumption minimization strategy (EEFC). The controller performance is analyzed for the World wide harmonized Light vehicles Test Cycle (WLTC) and randomly sequenced WLTCs under different initial conditions. This paper extends upon the earlier work where an LNT-SCR EATS supervisory control structure was proposed that optimizes based on the EEFC strategy. The future work will focus on extending the approach to more subsystems and characterizing the look ahead information.

Due to stricter emission regulations and more environmental awareness, the powertrain systems are moving toward higher fuel efficiency and lower emissions. In response to these pressing needs, new technologies have been designed and implemented by manufacturers. As a result of increasing complexity of the powertrain systems, their control and optimization become more and more challenging. Virtual powertrain calibration, also known as model-based calibration, has been introduced to transfer a part of test bench testing into a virtual environment, and hence considerably reduce time and cost of product development process while increasing the product quality. Nevertheless, virtual calibration has not yet reached its full potential in industrial applications. Volvo Penta has recently developed a virtual test cell named VIRTEC, which is used in an ongoing pilot project to meet the Stage V emission standards. The integrated powertrain system includes engine, Exhaust Aftertreatment System (EATS), and Engine Management System (EMS). The objective of this paper is to describe the essential aspects required to increase the contribution of virtual testing in powertrain calibration activities. These aspects comprise the following: Hardware-in-the-Loop (HiL) system, simulation models, and working process for joint virtual and physical testing to facilitate efficient powertrain development process. The current paper describes the design, test and verification of a calibration platform based on the requirements of the project. The future phases in the current project (Virtual Calibration at Volvo Penta) will cover validation of the platform by performing calibrations in industrial scales on the virtual system.

Low Carbon fuels will play a relevant role in the transportation sector contributing, over the powertrain technology progress, to mitigate global CO2 emissions. Compressed Natural Gas (CNG), mainly composed by methane, is one of the best candidate thanks to its chemical composition and to its wide diffusion and use. Blending Hydrogen in Natural Gas could represent a further step for a better CO2 footprint (considering renewable or biohydrogen) but also to optimize the combustion process, increasing the engine thermal efficiency and reducing pollutant formation. On the other hand, capability to automatically adapt the engine parameters to variable concentrations of Hydrogen in Natural Gas (in the range from 0% to 40% by volume) is a mandatory step to maintain engine performance, emissions and efficiency The activities described in this paper are part of a large collaborative project, “Biomethair”, funded by Regione Piemonte, where material specifications on gas tanks, valves, feeding lines, gas pressure regulator, engine pipes and injectors have been set and prototype components procured and implemented into the demonstrator vehicle to ensure safe operating conditions. In this paper a software algorithm is presented, able to provide, during normal car operation, real time estimates of methane-hydrogen composition, allowing the engine control system to adapt the control parameters engine. The algorithm is based on the innovative data-driven technology Direct Virtual Sensor, which allows to design the Virtual Sensor from the experimental data collected from a testing car, subject to suitable manoeuvres in different operational conditions, without requiring deep first principle modelling of the involved systems. The Virtual Sensor has been designed and implemented on the Electronic Control Unit of the demonstrator vehicle, giving suitably discretized estimates of Methane-Hydrogen composition, using measurements of engine revolution speed, of the lambda probe value and a variable from engine control unit. Experimental results of the Virtual Sensor performance evaluated in different operational conditions are presented.

Due to the prevalent fuel economy, research on electric hybrid vehicles (HEVs) has attracted recently widespread attention. However, most researches were focused on electrification, neglecting the crucial role of internal combustion engines (ICEs) in reducing fuel consumption. Holding the opinion that ICEs can contribute more in developing fuel economic vehicles, we present in this paper a new HEV topology with two ICEs - Dualhybrid. Two separate traction units, conventional drivetrain with ICE1at front axle and electric hybrid drivetrain with ICE2+battery at rear axle constitute the powertrain of this new HEV concept. One dimensional simulation with sub-models built upon different modelling methods is implemented. Energy management of Dualhybrid is identified with a rule-based control strategy. Base and Fullhybrid model were built as references and a comparative simulation among the three models as conducted. On the basis of the simulation results, an analysis of the efficiency of the powertrains was performed in detail. Results show that Dualhybrid equipped with two ICEs is more fuel economic compared to the reference models and has proven to be an effective HEV concept.

This paper shows the main results of a research activity carried out in order to investigate the impact of different hybridization concepts on vehicle fuel economy during standard homologation cycles (NEDC, FTP75, US Highway, Artemis). Comparative analysis between a standard passenger vehicle and three different hybrid solutions based on the same vehicle platform is presented. The following parallel hybrid powertrain solutions were investigated: Hybrid Electric Vehicle (HEV) solution (three different levels of hybridization are investigated with respect to different Electric Motor Generator size and battery storage/power capacity), High Speed Flywheel (HSF) system described as a fully integrated mechanical (kinetic) hybrid solution based on the quite innovative approach, and hydraulic hybrid system (HHV). In order to perform a fare analysis between different hybrid systems, analysis is also carried out for equal system storage capacities. All hybrid powertrain architectures include state-of-the-art hybrid components and are analyzed from the aspects of fuel economy related to the overall system efficiency, load point moving of the internal combustion engine due to energy flow control strategy operation, and regenerative braking (applying realistic drivability constraints). The simulations were performed within the IAV-VeLoDyn software environment. VeLoDyn (Vehicle Longitudinal Dynamics Simulation) is a modular and highly flexible Simulink-based software tool, which offers a straightforward simulation of longitudinal vehicle dynamics with special considerations on the driveline and model management functionality. In order to provide control and management of the hybrid powertrain system, a cycleindependent control strategy has been implemented into the supervisory hybrid control unit model, based on Equivalent Consumption Minimization Strategy (ECMS) approach. Due to the modular nature of the simulation tool, the control strategy was effectively implemented in all analyzed hybrid models with marginal modifications. In order to determine energy flows and validate hybrid powertrain behavior, a cycle-based energetic analysis was carried out, and the main results are presented in the paper.

This paper describes a vehicle-level simulation model for climate control and powertrain cooling developed and currently utilized at GM. The tool was developed in response to GM's need to speed vehicle development for HVAC and powertrain cooling to meet world-class program execution timing (18 to 24 month vehicle development cycles). At the same time the simulation tool had to complement GM's strategy to move additional engineering responsibility to its HVAC suppliers. This simulation tool called "e-Thermal" was quickly developed and currently is in widespread (global) use across GM. This paper describes GM's objectives and requirements for developing e-Thermal. The structure of the tool and the capabilities of the simulation tool modules (refrigeration, front end airflow, passenger compartment, engine, transmission, Interior air handling ...) is introduced. Model data requirements and GM's strategy for acquiring component data are also described. The paper includes an example of a typical application of the tool with sample output from the simulation and some comparison to actual test data from a vehicle under the same test scenario.

Future demands regarding emissions, fuel consumption and driveability lead to complex engine and power train control systems. The calibration of the increasing number of free parameters in the ECU s contradicts the demand for reduced time in the power train development cycle. This paper will focus on the automatic, unmanned closed loop optimization of driveability quality on a high dynamic engine test bed. The collaboration of three advanced methods will be presented: • Objective real time driveability assessment, to predict the expected feelings of the buyers of the car • Automatic computer assisted variation of ECU parameters on the basis of statistical methods like design of experiments (DoE). Thus data are measured in an automated process allowing an optimization based on models (e.g. neural networks). • A reproducible simulation of a real vehicle behavior, including power train and driver action simulation on a high dynamic engine test bed is used as well as special test runs for the automatic driveability calibration. Thus by utilizing this driveability model it will be possible, to produce market oriented calibrations by simply changing the target parameters. The current practice for optimizing driveability through ECU calibration, is an empirical process. It is performed utilizing complete vehicles on the road. In this paper an improved methodology will be presented. The ECU-parameters will be optimized with regard to the customer specific driveability demands within a traceable process. INTRODUCTION The paper describes a typical ECU-application work in the field of driveability and shows the possibility of automation of this task using the corresponding development tools on the test bed: • AVL-DRIVE: Objective real time driveability evaluation tool for applications in the vehicle, on test beds and in simulation • AVL-PUMA / ISAC: Dynamic engine testing plus simulation of the vehicle • AVL-CAMEO: Optimization of the ECU-Parameters according the specified driveability target TEST BED CONFIGURATION The used configuration on test bed is shown in the following picture. Additional to standard PUMA /ISAC configuration the test bed was equipped with AVLDRIVE, an ECU Application system and AVL-CAMEO. PUMA 5.6.1 ISAC 300 /KIWI V2.2 ECU Application System Test run Control

The present paper aims at developing an innovative procedure to create a one-dimensional (1D) real-time capable simulation model for a heavy-duty diesel engine. The novelty of this approach is the use of the top-level engine configuration, test cell measurement data, and manufacturer maps as opposite to common practice of utilizing a detailed 1D engine model. The objective is to facilitate effective model adjustments and hence further increase the application of Hardware-in-the-Loop (HiL) simulations in powertrain development. This work describes the development of Fast Running Model (FRM) in GT-SUITE simulation software. The cylinder and gas-path modeling and calibration are described in detail. The results for engine performance and exhaust emissions produced satisfactory agreement with both steady-state and transient experimental data. Therefore, the presented methodology shows a great potential for testing and validation of new control strategies in Engine Management System (EMS) and for optimizing engine performance using HiL systems. The model has been successfully used in powertrain testing and calibration in the VIRtual TEst Cell (VIRTEC) system at Volvo Penta.

Trucks, buses, automobiles and industrial equipment are negatively affected by the intrinsic weight, vibrational characteristics and critical speed of metal driveshafts. It has been proven that composite driveshafts are effective in overcoming these limitations. Indeed, the very nature of the composite materials (fiber and resinous binder) allows driveshafts to be designed to meet specific critical operational characteristics, and thus tailored to match the requirements of individual applications. 1.0 SUMMARY AND BACKGROUND Weight, vibrational, fatigue, and critical speed limitations have been recognized as serious problems in automotive and industrial drivetrains for many years. The associated effects and possible solutions have been subjected to detailed analysis. Numerous solutions such as flywheels, harmonic dampers, multiple shafts with additional bearings, and heavy rubber shock (vibration) absorbers have shown limited success in overcoming the problems, but always at the expense of increased weight, rotational inertia, and resistance in the drivetrain. Composite tubing has long been recognized to offer the potential of lighter weight driveshafts. Aerospace development efforts also demonstrated that correctly designed composite components have inherently superior fatigue and vibration damping characteristics to metals. Finally, the advent of higher modulus graphite fibers combined with these lighter weight and vibration damping characteristics allowed the design of driveshafts with much higher critical speed capabilities. These improvements have been realized and the reliability of composite driveshafts has been proven in heavy trucks, on race tracks, in automobiles and light trucks, and in industrial applications. ACPT, Inc. has been designing and producing carbon fiber composite driveshafts for these applications since 1982. 2.0 DRIVETRAIN VIBRATION PROBLEMS Vibration in drivetrains has been recognized as a major problem and has for many years been the subject of much theoretical analysis and trial-and-error vibrational control/reduction experimentation. 2.1 TRUCKS Mazziotti 1 in 1960 published a review and analysis of torsional vibrations associated with drivelines. He delineated some of the sources of non-uniform motion, which result in vibrational excitation of the drivetrain and presented a detailed mathematical analysis relating those sources of excitation to the physical dimensions, mechanical properties, and rotational speeds of driveshafts. He reported data firmly establishing the relationships between non-uniform motion sources and the natural frequency of the driveline components. He concluded that vibrations can be amplified or subdued while being transmitted through the driveline and recommends that (with metal shafts) the driveline be operated at no less than 1.5 times the natural frequency (torsional) of the system. Herein it was assumed that rubber springs, flywheels, flexible couplings and other natural frequency reduction additions were the best way to modify the natural frequency. In 1960 the technology did not exist to design or produce carbon fiber composite driveshafts. Mazziotti also stated that, “a resonant condition can produce objectionable disturbances as follows: 1. The high oscillating torque value can result in failure in rotating members. 2. Variable reactions on supporting members can be a source of objectionable noise and vibration. 3. Damage to gears, bearings, and other components can occur because of non-uniform loading.” All of these predictions have been proven to be accurate and are still sources of aggravation for truck designers, builders and operators. In recognition of, and in order to assist in the design of better truck drive systems, SAE paper #942322, 2 published by Spicer, division of Dana, describes a detailed torsional analysis computer simulation of truck drivetrains. The paper supports Mazziotti’s work and concludes, “torsional vibrations cause comfort problems for occupants and produce component failures.” “Torsionals also introduce dynamic loads on top of the mean static torque transmitted through the power train.” “...could easily cause catastrophic dynamic fatigue failures.” “At least responsible for wear problems at springs, splines, gear teeth, etc, eventually leading to the failure of these components.” This paper also presents a fairly detailed list of references on the subject of vibrations and their effect on automotive drivelines. Higher specific modulus (modulus/density) gives carbon fiber shafts the ability to run longer one piece lengths than metal shafts. A composite shaft, of the same length as a metal shaft, will start to resonate laterally at a much higher speed and have correspondingly increased margin of safety at the higher RPMs. This allows one piece composite shafts to replace two piece steel shafts. The benefits of eliminating the two piece shafts are significant reductions in weight, noise, vibration and harshness. The composite shafts have also proven to dampen vibration and absorb shock, greatly reducing wear on other drivetrain components as well as increasing tire traction. In a test started in August of 1994, a one piece carbon fiber driveshaft was installed in a garbage truck operating in Texas, Figure 2-1 and 2-2. This shaft replaced a two piece steel shaft and a center bearing, Figure 2-3. The resultant weight savings was about 80 lbs. The shaft has now seen daily use for the last two years in what has been described as one of the most torturous commercial truck applications possible. Absolutely no problems have been recorded. The operator is maintaining records of repairs with which to compare histories with other driveline components of identical trucks in the fleet. It is still too early to draw any conclusions from these records. It can be said, however, that the carbon fiber shaft is performing flawlessly. Figure 2-1: Garbage Truck Operating with One Piece Carbon Fiber Driveshaft The garbage truck shaft replacement was a cooperative effort with Inland Empire Driveline Services, Ontario, CA. They have been instrumental in helping us to develop and supply carbon fiber driveshafts to the automotive community. Inland has successfully developed and employs aluminum welding techniques, which resulted in moving torque testing failures from the weld joint to the U-joint. They have provided constant support in obtaining information and hardware mating carbon fiber tubing to the correct driveshaft fittings. Inland Empire Driveline Services continues to be of great technical assistance and currently performs all of the welding and balancing required in the manufacture of our carbon fiber driveshafts. Other direct experience is being obtained from OEM’s. Three major OEMs have run composite driveshafts on test tracks and have performed extensive laboratory evaluations. One of these companies is now running “on the road” fleet evaluations. 2.2 AUTOMOTIVE AND LIGHT TRUCKS The vibration problems in automobiles and light trucks are not so much “catastrophic failures”, but rather more of weight, noise, harshness and passenger discomfort. Component failure can still be a problem at high speeds, as natural resonant frequencies of the driveshaft are approached. GKN 3 states that, “the Mark VIII is top speed limited by its long steel driveshaft to 128 mph. Above 128 mph the driveshaft gets into a bending and vibration frequency that would eventually tear it apart.” They continue that, “to eliminate this problem most high speed European cars usually have a two piece shaft connected through a center bearing.” Carbon fiber driveshafts can alleviate this problem. 2.3 INDUSTRY Heavy duty industrial drivetrains, such as pump shafts and cooling tower driveshafts, suffer from similar torsional vibrations, natural frequency, and critical speed problems as heavy duty trucks and buses. The industrial community has demonstrated that composite driveshafts will reliably solve these problems. Figure 2-2: One Piece Carbon Fiber Driveshaft, Garbage

The U.S. Department of Energy (DOE) has invested considerable research and development (R&D) effort into Plug-in Hybrid Electric Vehicle (PHEV) technology because of the potential fuel displacement offered by the technology. DOE’s PHEV R&D Plan [1], which is driven by the desire to reduce dependence on foreign oil by diversifying the fuel sources of automobiles, describes the various activities required to achieve the goals. The U.S. DOE will use Argonne’s Powertrain Systems Analysis Toolkit (PSAT) to guide its analysis activities, stating, “Argonne’s Powertrain Systems Analysis Toolkit (PSAT) will be used to design and evaluate a series of PHEVs with various 'primary electric' ranges, considering all-electric and charge-depleting strategies.” PSAT was used to simulate three possible chargedepleting (CD) PHEV control strategies for a power split hybrid. Trip distance was factored into the CD strategies before the cycle was started. The results are examined in this paper to determine if any of the three strategies could reduce the power split configuration’s fuel consumption beyond what a simple all-electrical strategy followed by a charge-sustaining (CS) strategy could afford. The results show that the improvements for this configuration are small and depend on the ratio of the engine efficiency when operating in CS mode to the engine efficiency when operating in CD mode.

Because of their high efficiency and low emissions, fuelcell vehicles are undergoing extensive research and development. As the entire powertrain system needs to be optimized, the requirements of each component to achieve FreedomCAR goals need to be determined. With the collaboration of FreedomCAR fuel cell, energy storage, and vehicle Technical Teams, Argonne National Laboratory (ANL) used several modeling tools to define the energy storage requirements for fuel cell vehicles. For example, the Powertrain System Analysis Toolkit (PSAT), which is a transient vehicle simulation software, was used with a transient fuel cell model derived from the General Computational Toolkit (GCtool). This paper describes the impact of degree of hybridization, control strategy, and energy storage technology on energy storage requirements for a fuel cell SUV vehicle platform.

e-Thermal is a vehicle level thermal analysis tool developed by General Motors to simulate the transient performance of the entire vehicle HVAC and Powertrain cooling system. It is currently in widespread (global) use across GM. This paper discusses the details of the airconditioning module of e-Thermal. Most of the literature available on transient modeling of the air conditioning systems is based on finite difference approach that require large simulation times. This has been overcome by appropriately modeling the components using Sinda/Fluint. The basic components of automotive air conditioning system, evaporator, condenser, compressor and expansion valve, are parametrically modeled in Sinda/Fluint. For each component, physical characteristics and performance data is collected in form of component data standards. This performance data is used to curve fit parameters that then reproduce the component performance. These components are then integrated together to form various A/C system configurations including orifice tube systems, txv systems and dual evaporator systems. The A/C subsystem uses airflow rates, temperatures, humidity’s and compressor speed as inputs. The outputs include overall system energy balance, system COP, refrigerant flow rates and system pressures. The A/C simulation runs about three times faster to three times slower than real time. The modeling technique used is also capable of tracking the effect of system charge on the overall system performance. A database of automotive air conditioning components accompanies the simulation tool. This database is then integrated in e-Thermal to provide the component data for modeling. Validation results for component level models are demonstrated. They form the basis of system level models. System level validation is also demonstrated. The simulation times vary from 3 times faster than real time to 5 times slower than real time depending on the nature of the simulation.

An integrated vehicle system simulation has been developed to take advantage of advances in physical process and component models, flexibility of graphical programming environments (such as MATLAB-SIMULINK), and ever increasing capabilities of engineering workstations. A comprehensive, transient model of the multi-cylinder engine is linked with models of the torque converter, transmission, transfer case and differentials. The engine model is based on linking the appropriate number of single-cylinder modules, with the latter being thermodynamic models of the in-cylinder processes with built-in physical sub-models and transient capabilities to ensure high fidelity predictions. Either point mass or multi-body vehicle dynamics models can be coupled with the powertrain module to produce the ground vehicle simulation. The integrated simulation can be used for predictions of dynamic response and performance of engine and driveline systems, for assessment of alternative system configurations and for integration studies in conjunction with the rest of the components of ground vehicles. Various illustrative studies are conducted for heavy-duty truck vehicles to demonstrate the capability of the simulation to predict performance and transient system response. Copyright © 1999 Society of Automotive Engineers, Inc.

Power dense internal combustion engines (ICEs) are interesting candidates for onboard charging devices in different electric powertrain applications where the weight, volume and price of the energy storage components are critical. Single-cylinder naturally aspirated two-stroke spark-ignited (SI) engines are very small and power dense compared to four-stroke SI engines and the installation volume from a single cylinder two-stroke engine can become very interesting in some concepts. During charged conditions, four-stroke engines become more powerful than naturally aspirated two-stroke engines. The performance level of a two-stroke SI engines with a charging system is less well understood since only a limited number of articles have so far been published. However, if charging can be successfully applied to a two-stroke engine, it can become very power dense. This article outlines some of the challenges related to charging systems for a single-cylinder crank case scavenged two-stroke SI engine. Different charging scenarios were investigated and a charging system was selected and optimized to meet the scavenging and gas exchange needs of two-stroke engine. A 125 cc single-cylinder two-stroke engine with a turbocharger was simulated and tested successfully to a performance level of 400 kW/L.

The requirements set for the next-generation powertrain systems (e.g. performance and emissions) are becoming increasingly stringent with ever-shortening time-to-markets at reduced costs. To remain competitive automotive companies are progressively relying on model-driven development and virtual testing. Virtual test benches, such as Hardware-in the-Loop simulators, are powerful tools to reduce the amount of physical testing and speed up engine software calibration process. The introduction of these technologies places new, often conflicting demands (such as higher predictability, faster simulation speed, and reduced calibration effort ) upon simulation models used at Hardware-in-the-Loop test benches. The new models are also expected to offer compliance to industry standards, performance and usability to further increase the usage of virtual tests in powertrain development. The present work describes a novel verification process for creating a fast running model for a heavy-duty diesel engine using FRM-d Builder in GT-SUITE simulation software. The approach uniquely applies the combination physical modelling and parameter estimation techniques, while relying solely on test cell measurements without data maps from the manufactures (e.g. for turbine and compressor). The procedure provides detailed description for subsystem calibration for turbocharger and intake path. The developed model is successfully employed at the VIRTEC system in Volvo Penta. The simulation results for engine performance and exhaust emissions provide favourable results for both steady-state and transient operating conditions.