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SAE International Journal of Commercial Vehicles
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Driveline System - Suspension Interaction in a 6×6 Terrain Truck

SAE International Journal of Commercial Vehicles

The University of Alabama at Birmingham-Vladimir V. Vantsevich
  • Journal Article
  • 2012-01-1915
Published 2012-09-24 by SAE International in United States
Normal and longitudinal dynamics of vehicles interrelates via the normal and longitudinal tire reactions. The normal reactions are supposed to be formed by characteristics of the suspension system and tires, and the longitudinal forces in the tire patches are produced by the driveline system by supplying torques to the drive wheels. Usually, the normal and longitudinal reactions, independently generated by the two vehicle systems, are considered to interrelate, but not to impact each other.An analytical study presented in this paper showed that the normal tire reactions are formed not only by the design of suspension but also by the longitudinal tire reactions (circumferential wheel forces), which follow from the wheel torques supplied by the driveline system. A 6×6 vehicle with A-type suspension systems at all three axles exhibits different normal tire reactions at the drive axles during motion even when the static weight distribution is equal. The paper presents this analytical study of the influence of the circumferential wheel forces on the normal reactions at the wheels.At the same time, the difference in the normal…
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Powertrain Cycle for Emission Certification

SAE International Journal of Commercial Vehicles

Cummins Inc.-Morgan Andreae, Zhen Sun
  • Journal Article
  • 2012-01-2059
Published 2012-09-24 by SAE International in United States
In August of 2011, the US Environmental Protection Agency issued new Green House Gas (GHG) emissions regulations for heavy duty vehicles. These regulations included new procedures for the evaluation of hybrid powertrains and vehicles. One of the hybrid options allows for the evaluation of an engine plus a hybrid transmission (a powertrain). For this type of testing, EPA has proposed simulating a vehicle following the hybrid vehicle test procedures, including the use of the vehicle cycles and the A to B comparison testing - as required for the full vehicle evaluation option.This paper proposes an alternative approach by defining a powertrain cycle. The powertrain cycle is based on the heavy duty engine emissions cycle - the transient FTP cycle. Simulation and test results are presented showing similar performance over the engine and vehicle cycles. This approach offers several advantages as compared to the procedure described in EPA's GHG rule. Linking the powertrain cycle to the engine cycle ensures an equivalent evaluation as compared to the engine test, and allows evaluation against the engine standard instead…
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A Method for Developing Specific Reference Cycles or Alternatively Test Cases for Commercial Vehicles and Their Auxiliary Systems

SAE International Journal of Commercial Vehicles

IPEK - Institute of Product Engineering-Friedrich Philipp Brezger, Albert Albers
  • Journal Article
  • 2012-01-2026
Published 2012-09-24 by SAE International in United States
In contrast to passenger cars, commercial vehicles exist in many layouts for different customer applications. The Daimler AG provides with their Mercedes Benz Trucks a product portfolio of 6 commercial vehicles (Econic, Atego, Axor, Actros, Zetros, Unimog), which are available in a multiplicity of model variants.Therefore, the well-known driving cycles of passenger cars such as NEDC (Europe), the 10-15 mode (Japan), the FTP & FTP75 (USA) and others cannot be used in regard to fuel consumption or dimensioning of a commercial vehicle [1, 6, 15]. A diversification of type and usage of the commercial vehicles is obligatory necessary, as already shown in publications of Holloh et al. [10]However, this paper offers a method which uses collected data from customers, in order to develop objective reference cycles or test cases. This described method can be equally used for both, creating the reference cycles of commercial vehicles mentioned above, as well as passenger cars. Especially when moving on to the more complex operating strategies and operating points or vehicles with many different auxiliary systems, this method is…
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Dynamic Test Scheduling in Hardware In the Loop Simulation of Commercial Vehicles

SAE International Journal of Commercial Vehicles

University of Connecticut/Scania AB-Tenil Cletus
  • Journal Article
  • 2012-01-2028
Published 2012-09-24 by SAE International in United States
Modern day commercial vehicles use Electronic Control Units that are complex. Integration testing of these Control Units as one control system has many challenges. Many of these challenges are met by driving Integration test activities towards automation, based on Hardware In the Loop (HIL) simulation. The simulation scenarios consist of functional tests designed with the aim of replicating real world tests that are performed in an actual vehicle. However, most of the HIL simulators used these days in industry have functional tests which are assumed to be independent and are executed in a sequence pre-determined by a Test engineer. We demonstrate that the assumption of test independence doesn't hold well in many simulation scenarios. Integration test process efficiency can be shown to be improved by dynamically scheduling functional tests while simulation is running instead of a pre-determined sequence. We propose two solutions to for the dynamic test scheduling problem. One solution is to model the integration test process as a state machine. The second proposed solution is functionally similar to a state machine but its…
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Compression-Release Engine Brake Modeling and Braking Performance Simulation

SAE International Journal of Commercial Vehicles

Navistar, Inc.-Peirong Jia, Qianfan (Harry) Xin
  • Journal Article
  • 2012-01-1968
Published 2012-09-24 by SAE International in United States
A diesel engine multi-cylinder valvetrain model including a hydraulic engine braking system was developed. The model can be used for valvetrain dynamics analysis in both engine firing and braking conditions. Moreover, it can be used to investigate engine braking performance with conjugated analysis by combining the valvetrain model with an engine thermodynamic cycle simulation model. Dynamic valve lift profiles, which are important for accurate engine performance simulations, can be simulated with the model, including valve floating prediction for each cylinder during engine braking. The valvetrain model was used in the design of a diesel engine brake system and in the analysis of engine braking performance at the sea level and different high altitude and ambient temperature conditions. Valvetrain dynamics and the impact of EGR (exhaust gas recirculation) valve leakage or opening on engine braking performance were also evaluated.
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A Multi-Objective LMI-Based Antiroll Control System

SAE International Journal of Commercial Vehicles

Jilin University Automotive Engrg Colleg-Jian Zhao
Virginia Tech.-Saied Taheri
  • Journal Article
  • 2012-01-1904
Published 2012-09-24 by SAE International in United States
A long standing problem with heavy vehicle stability has been rollover. With the higher center of gravity, heavier loads, and narrower tracks (as compared to passenger vehicles), they have a lower rollover stability threshold. In this paper, a rollover stability control algorithm based on a two-degrees-of-freedom (DOF) and a three-DOF vehicle model for a two-axle truck was developed. First, the 3DOF model was used to predict the future Lateral load Transfer Rate (LTR). Using this LTR value, the dynamic rollover propensity was estimated. Then, a robust output feedback gain control rollover stability control algorithm based on the combination of active yaw control and active front steering control was developed. A H₂/H∞/poles placement multi-objective control strategy was developed based on the 2DOF reference model. After the control objectives were determined, the Linear Matrix Inequality (LMI) technique was utilized to solve the restrictions and to carry out the output feedback gain for the multi-input multi-output (MIMO) system. Finally, utilizing the commercial software TruckSim, the rollover stability control was evaluated using fishhook and step steering maneuvers. The simulation…
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Study of Vibration from Steering Wheel of an Agricultural Tractor

SAE International Journal of Commercial Vehicles

Tractors and Farm Equipment Limited-Ananth Sakthivel, Sethuraman Sriraman, Rakesh B Verma
  • Journal Article
  • 2012-01-1908
Published 2012-09-24 by SAE International in United States
Steering wheel vibration is one of the major factors in determining the operator comfort in agricultural tractors. Main sources of steering wheel vibration are engine imbalance, resonance of steering system, lesser damping, road / field induced vibration, etc. The European Council directive 2002/44/EC recommendations are taken as guidelines in this work.Steering vibration study was conducted on various tractor models (40 - 50 kW range) and one tractor was identified for improvement. Upon detailed analysis on that particular tractor, it was found that the resonance of steering system with engine excitation is the root cause for excessive vibration. Various methods to reduce vibration due to resonance were considered, such as shifting the natural frequency away from the second order engine frequency and increasing damping coefficient to reduce the vibration amplitude at resonance. Six different concepts were generated and analyzed using the design assessment matrix. Two concepts were selected, namely radial damper and axial damper concepts for further processing. These concepts were tested and a significant reduction in vibration levels was achieved. Axial damper concept offers higher…
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Development of a Fuel Consumption Test Procedure for Refrigeration Units

SAE International Journal of Commercial Vehicles

FPINNOVATIONS-Marius-Dorin Surcel
  • Journal Article
  • 2012-01-2060
Published 2012-09-24 by SAE International in United States
This project's objective was the development of a test procedure to evaluate the impact of the refrigerated van box on the fuel consumption of the refrigeration unit. The scope of the project included a review of the test procedures, the development of a testing methodology for measuring the fuel consumption of the refrigeration unit on a specific duty cycle, and testing with a view to validating the methodology.Road and track tests are subject to variations in conditions, and controlling or accounting for these variables as much as possible is an important part of ensuring accurate results. However, when testing a refrigerated van on the track or on the road, it is very difficult to eliminate variable external influences and to isolate the particular influence of the refrigerated van on the refrigeration unit's fuel consumption. For this reason, tests were conducted in an environmental chamber in controlled temperature and humidity conditions.Validation tests took place in an environmental chamber at an ambient temperature of +32°C. The refrigerated box had an interior temperature of −10°C. The tests aimed…
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Analysis of Gear Geometry and Durability with Asymmetric Pressure Angle

SAE International Journal of Commercial Vehicles

Mahindra & Mahindra Ltd-Sagar Jadhav
Mahindra Engineering Services-Amit Sandooja
  • Journal Article
  • 2012-01-1995
Published 2012-09-24 by SAE International in United States
Gear design is one of the most critical components in the Mechanical Power Transmission industry. Among all the gear design parameters pressure angle is the most critical parameter, which mainly affects the load carrying capacity of the gear. Generally gears are designed with a symmetric pressure angle for drive and coast side. It means that both flank side of gear are able to have same load carrying capacity. In some applications, such as in wind turbines, the gears experience only uni-directional loading. In such cases, the geometry of the drive side need not be symmetric to the coast side. This allows for the design of gears with asymmetric teeth. Therefore new gear designs are needed because of the increasing performance requirements, such as high load capacity, high endurance, long life, and high speed. These gears provide flexibility to designers due to their non-standard design. If they are correctly designed, they can make important contributions to the improvement of designs in aerospace industry, automobile industry, and wind turbine industry.In this paper we present a mathematical model…
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Modeling Combined Braking and Cornering Forces Based on Pure Slip Measurements

SAE International Journal of Commercial Vehicles

Konghui Guo
Jilin Univ.-Nan Xu
  • Journal Article
  • 2012-01-1924
Published 2012-09-24 by SAE International in United States
A novel predictable tire model has been proposed for combined braking and cornering forces, which is based on only a few pure baking and pure cornering tests. It avoids elaborate testing of all kinds of combinations of braking and side forces, which are always expensive and time consuming. It is especially important for truck or other large size tires due to the capability constraints of tire testing facilities for combined shear forces tests.In this paper, the predictive model is based on the concept of slip circle and state stiffness method. The slip circle concept has been used in the COMBINATOR model to obtain the magnitude of the resultant force under combined slip conditions; however the direction assumption used in the COMBINATOR is not suitable for anisotropic tire slip stiffness. The state stiffness method, by which the variation of resultant force direction caused by anisotropy of tire slip stiffness can be described well and then the longitudinal and lateral forces under combined situations can be obtained separately. In addition, the friction ellipse is introduced in state…
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