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SAE International Journal of Passenger Cars Mechanical Systems
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Application of a New Method for Comparing the Overall Energy Consumption of Different Automotive Thermal Management Systems

SAE International Journal of Passenger Cars - Mechanical Systems

Jan Christoph Menken, Thomas Weustenfeld, Jürgen Köhler
  • Journal Article
  • 06-11-04-0024
Published 2018-10-03 by SAE International in United States
This article applies a new method for the evaluation and estimation of real-life energy consumption of two different thermal management systems based on driving behavior in the course of the day. Recent attempts to find energy-efficient thermal management systems for electric and plug-in hybrid electric vehicles have led to using secondary loop systems as an alternative approach for meeting dynamic heating and cooling demands and reducing refrigerant charge. However, the additional layer of thermal resistance, which influences the system’s transient behavior as well as passenger compartment comfort during cool-down or heat-up, makes it difficult to estimate the annual energy consumption. In this article, the overall energy consumption of a conventional and a secondary loop system is compared using a new method for describing actual customers’ driving behavior in the course of the day. Therefore, a reduced, representative set of 24-hour driving and stopping cycles from an actual data set of travel and transportation patterns in the United States is used. Additionally, respective weather data is considered. This method helps reduce simulation and testing effort significantly…
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Performance Margin for Geometric Road Design

SAE International Journal of Passenger Cars - Mechanical Systems

Virginia Polytechnic Institute and State University-Yong-suk Kang, John B. Ferris
  • Journal Article
  • 06-11-04-0022
Published 2018-08-08 by SAE International in United States
Although several methods exist for measuring the performance capability of a vehicle, many require detailed knowledge of the forces acting at each tire contact patch or do not account for both the vehicle dynamics and the road geometry. A simple vehicle model is proposed to estimate the upper limit of performance capability for a given operating condition (the Performance Envelope) based on the Effective Friction and the road geometry (slope and cross-slope). The Effective Friction accounts for both the vehicle dynamics and road surface properties and is estimated, through simulation or experimentation, using two standard vehicle dynamics tests: constant radius cornering and straight-line braking. The Performance Margin is defined as the additional performance capability available before the vehicle reaches the Performance Envelope, both represented in the intuitive units of gravity. The Performance Margin is applicable to both geometric road design and vehicle control; both of which are crucial as transportation agencies and vehicle manufacturers prepare for the introduction of autonomous vehicles.
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Steady Aeroelastic Response Prediction and Validation for Automobile Hoods

SAE International Journal of Passenger Cars - Mechanical Systems

Honda R&D Americas, Inc.-Austin Kimbrell, Peter Kang
Ohio State University-Justin Pesich, Jack McNamara
  • Journal Article
  • 06-11-04-0021
Published 2018-07-10 by SAE International in United States
The pursuit of improved fuel economy through weight reduction, reduced manufacturing costs, and improved crash safety can result in increased compliance in automobile structures. However, with compliance comes an increased susceptibility to aerodynamic and vibratory loads. The hood in particular withstands considerable aerodynamic force at highway speeds, creating the potential for significant aeroelastic response that may adversely impact customer satisfaction and perception of vehicle quality. This work seeks an improved understanding in computational and experimental study of fluid-structure interactions between automobile hoods and the surrounding internal and external flow. Computational analysis was carried out using coupled CFD-FEM solvers with detailed models of the automobile topology and structural components. The experimental work consisted of wind tunnel tests using a full-scale production vehicle. Comparisons between numerical and experimental results yielded important insights into required modeling fidelity, coupling, and challenges in validation for the aeroelastic response of automobile hoods.
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Vehicle Stability Control through Optimized Coordination of Active Rear Steering and Differential Driving/Braking

SAE International Journal of Passenger Cars - Mechanical Systems

Dongfeng Motor Corporation-Zhao Yachao
SAIC-GM Wuhan Branch-Fang Cheng
  • Journal Article
  • 06-11-03-0020
Published 2018-07-05 by SAE International in United States
In this article, a hierarchical coordinated control algorithm for integrating active rear steering and driving/braking force distribution (ARS+D/BFD) was presented. The upper-level control was synthesized to generate the required rear steering angle and external yaw moment by using a sliding-mode controller. In the lower-level controller, a control allocation algorithm considering driving/braking actuators and tire forces constraints was designed to assign the desired yaw moment to the four wheels. To this end, an optimization problem including several equality and inequality constraints were defined and solved analytically. Finally, computer simulation results suggest that the proposed hierarchical control scheme was able to help to achieve substantial enhancements in handling performance and stability. Moreover, the comparison between ARS+D/BFD and AFS+D/BFD (active front steering and driving/braking force distribution) by using the proposed controller was presented and analyzed.
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Parametric Study of Asymmetric Side Tapering in Constant Cross Wind Conditions

SAE International Journal of Passenger Cars - Mechanical Systems

Max Varney, Martin Passmore, Adrian Gaylard
  • Journal Article
  • 06-11-03-0018
Published 2018-06-28 by SAE International in United States
Sports Utility Vehicles (SUVs) often have blunt rear end geometries for design and practicality, which is not typically aerodynamic. Drag can be reduced with a number of passive and active methods, which are generally prioritised at zero yaw, which is not entirely representative of the “on road” environment. As such, to combine a visually square geometry (at rest) with optimal drag reductions at non-zero yaw, an adaptive system that applies vertical side edge tapers independently is tested statically. A parametric study has been undertaken in Loughborough University’s Large Wind Tunnel with the ¼ scale Windsor Model. The aerodynamic effect of implementing asymmetric side tapering has been assessed for a range of yaw angles (0°, ±2.5°, ±5° and ±10°) on the force and moment coefficients. This adaptive system reduced drag at every non-zero yaw angle tested, from the simplest geometry (full body taper without wheels) to the most complex geometry (upper body taper with wheels) with varying levels of success; providing additional drag reductions from 3% to 125%. The system also shows potential to beneficially modify…
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Evaluation of the Energy Consumption of a Thermal Management System of a Plug-In Hybrid Electric Vehicle Using the Example of the Audi Q7 e-tron

SAE International Journal of Passenger Cars - Mechanical Systems

AUDI AG-Jan Christoph Menken, Klaus Strasser, Thomas Anzenberger, Christian Rebinger
  • Journal Article
  • 06-11-03-0017
Published 2018-06-18 by SAE International in United States
The transition of vehicle propulsion technologies away from conventional internal combustion engines toward more electrically dominant systems such as plug-in hybrid electric vehicles (PHEV) poses new challenges for vehicle thermal management systems. Especially at low ambient temperatures, consumer demand for cabin comfort as well as legislatively imposed safety considerations significantly reduce the electric driving range because only electric energy can be used for heating during emissions-free driving modes. Recent developments to find energy efficient thermal management systems for electric and plug-in electric vehicles have led to the implementation of automotive heat pump systems. As an alternative approach to meet dynamic heating demands and safety regulations, these systems use heat at a low temperature level, for example the waste heat of electric drivetrain components, to heat the passenger compartment efficiently and therefore increase the electric driving range. Under moderate and humid environmental conditions, thermal management systems operate in a so called reheat mode. This safety-relevant reheat mode is characterized by the cooling and resulting dehumidification of the in-stream air and the subsequent heating to maintain cabin…
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Exhaust Manifold Thermal Assessment with Ambient Heat Transfer Coefficient Optimization

SAE International Journal of Passenger Cars - Mechanical Systems

Ford Otomotiv Sanayi AS-Baran Celikten, İpek Duman, Caner Harman, Sinan Eroglu
  • Journal Article
  • 06-11-03-0016
Published 2018-06-04 by SAE International in United States
Exhaust manifolds are one of the most important components on the engine assembly, which is mounted on engine cylinder head. Exhaust manifolds connect exhaust ports of cylinders to the turbine for turbocharged diesel engine therefore they play a significant role in the performance of engine system. Exhaust manifolds are subjected to very harsh thermal loads; extreme heating under very high temperatures and cooling under low temperatures. Therefore designing a durable exhaust manifold is a challenging task. Computer aided engineering (CAE) is an effective tool to drive an exhaust manifold design at the early stage of engine development. Thus advanced CAE methodologies are required for the accurate prediction of temperature distribution. However, at the end of the development process, for the design verification purposes, various tests have to be carried out in engine dynamometer cells under severe operating conditions. The test running durations up to 2500 hours are required for the heavy duty (HD) diesel engine exhaust manifold; therefore they are very expensive and time consuming. In order to avoid this additional costs, having first time…
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Design, Analysis, Simulation and Validation of Automobile Suspension System Using Drive-Shaft as a Suspension Link

SAE International Journal of Passenger Cars - Mechanical Systems

College of Engineering Pune-Shubham Ramchandra Nehe, Ashay Ghogare, Shubham Vatsa, Lokesh Tekade, Shantanu Thakare, Prajakta Yadav, Pranav Shool, Pratik Wankhade, Vivekanand Dhakane, Satish Charjan
  • Journal Article
  • 06-11-02-0011
Published 2018-04-18 by SAE International in United States
With increasing demands for higher performance along with lower vehicle emissions, lightweight vehicle system construction is key to meet such demands. Suspension and transmission assemblies being the key areas for weight-reduction, we have designed a revolutionary new type of suspension system which combines the suspension links with the powertrain assembly and thus completely eliminates one suspension member. Less weight means lower fuel-consumption with improved passenger-comfort and road-holding due to reduction in unsprung mass. Elimination of a suspension link reduces the overall cost of material, machining & fabrication making our design cost-effective than existing setups. This article deals with the design and implementation of of our concept. A working prototype is also constructed and tested which completely validates our design. Our design has major benefits of ultralight-weight construction with reduced space requirement and component-count and improved serviceability.
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Introducing the Modified Tire Power Loss and Resistant Force Regarding Longitudinal Slip

SAE International Journal of Passenger Cars - Mechanical Systems

K.N. Toosi University of Technology-Shahram Azadi
University of Tehran-Naser Sina, Vahid Esfahanian, Mohammad Reza Hairi Yazdi
  • Journal Article
  • 06-11-02-0014
Published 2018-04-18 by SAE International in United States
Investigation of vehicle resistant forces and power losses is of crucial importance owing to current state of energy consumption in transport sector. Meanwhile, considerable portion of resistant forces in a ground vehicle is traced back to tires. Pneumatic tires are known to be a source of energy dissipation as a consequence of their viscoelastic nature. The current study aims to provide a modification to tire resistance by considering the power loss in a tire due to longitudinal slip. The modified tire resistance is comprised of rolling resistance and a newly introduced resistance caused by tire slip, called slip resistance. The physical model is chosen for parameters sensitivity study since the tractive force is described in this model via tangible physical parameters, e.g. tire tangential stiffness, coefficient of friction, and contact patch length. Hence, the tire physical model is capable to investigate the influence of different parameters such as coefficient of friction, normal load, and inflation pressure on dependency of tractive force upon longitudinal slip. The results show that tractive force is a determining factor in…
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Development of Safe and Sustainable EPAS (Electric Power Assist Steering) System for Emerging Markets

SAE International Journal of Passenger Cars - Mechanical Systems

Tata Motors Ltd-Swapnil Salunkhe
Tata Technologies Ltd-Anand Mule, Jayant Kumar Sinha, Shrihari Matsagar
  • Journal Article
  • 06-11-02-0012
Published 2018-04-07 by SAE International in United States
The vehicle attributes developed for emerging markets like India are unique because of different topographical conditions, diversity and culture within the different states. Major attributes in vehicle development process is development of safe and sustainable vehicle systems (steering, brakes etc.) for the driver. India is presently an emerging market for automotive sector. With booming economy, purchasing power of the consumer has gone up in the past few years. Most of young population of India have started buying the cars. At the same time, India’s road infrastructure, vehicle regulations have exalted over the years. The consumer cognizance towards the vehicles have started changing now. They want safer, robust system in their vehicles with new convenience features at affordable cost. In recent years, almost all OEM’s in India have migrated steering systems from HPAS to EPAS for payback on fuel economy and weight. This article discusses development of EPAS system with the following features for India market based on customer expectations and benchmark data.Assist control at different speedsActive steering returnabilityActive damping controlSoft stop- at rack bar end…
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