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In-Service Emissions from Model Year 2012 Hydraulic Hybrid and Model Year 2008 Conventional Diesel Package Delivery Trucks

SAE International Journal of Commercial Vehicles

Calstart-Jean-Baptiste Gallo
Engine Fuel & Emissions Engineering Inc-Christopher Weaver
  • Journal Article
  • 2015-01-9016
Published 2015-05-01 by SAE International in United States
In-service emissions measurements were conducted on two package delivery trucks: one model year 2008 FCCC MT-55 conventional diesel and one model year 2012 FCCC MT-55 hydraulic hybrid (HHV). Mass emissions of CO2, CO, NOx, PM, and THC from the HHV and the conventional diesel test vehicle were each measured under conditions closely simulating normal package delivery operation.The HHV demonstrated a 29.4% improvement in fuel economy and a 17.4% reduction in CO2 emissions compared to the conventional diesel vehicle. The HHV showed its best potential in operating areas characterized by low driving speeds and high number of stops (“pick-up and delivery”) with a 40.5% improvement in fuel economy and a 21.2% reduction in CO2 emissions. Depending on operating conditions such as terrain, driver behavior and driving / traffic conditions, some fuel saving were achieved on operating areas characterized by high driving speeds and low number of stops (“highway / arterial”), but savings remained small.While the different EPA emission certification levels prevented the direct comparison of NOx emissions between the conventional diesel truck and the HHV, testing…
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Analyzing Rollover Indices for Critical Truck Maneuvers

SAE International Journal of Commercial Vehicles

Linkoping Univ.-Kristoffer Lundahl, Chih Feng Lee, Erik Frisk, Lars Nielsen
  • Journal Article
  • 2015-01-1595
Published 2015-04-14 by SAE International in United States
Rollover has for long been a major safety concern for trucks, and will be even more so as automated driving is envisaged to becoming a key element of future mobility. A natural way to address rollover is to extend the capabilities of current active-safety systems with a system that intervenes by steering or braking actuation when there is a risk of rollover. Assessing and predicting the rollover is usually performed using rollover indices calculated either from lateral acceleration or lateral load transfer. Since these indices are evaluated based on different physical observations it is not obvious how they can be compared or how well they reflect rollover events in different situations.In this paper we investigate the implication of the above mentioned rollover indices in different critical maneuvers for a heavy 8×4 twin-steer truck. The analysis is based on optimal control applied to a five degrees of freedom chassis model with individual wheel dynamics and high-fidelity tire-force modeling. Driving scenarios prone to rollover accidents are considered, with a circular-shaped turn and a slalom maneuver being studied…
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Active Brake Judder Compensation Using an Electro-Hydraulic Brake System

SAE International Journal of Commercial Vehicles

Ilmenau Technical Univ-Dzmitry Savitski, Valentin Ivanov
Linköping Univ-Chih Feng Lee
  • Journal Article
  • 2015-01-0619
Published 2015-04-14 by SAE International in United States
Geometric imperfections on brake rotor surface are well-known for causing periodic variations in brake torque during braking. This leads to brake judder, where vibrations are felt in the brake pedal, vehicle floor and/or steering wheel. Existing solutions to address judder often involve multiple phases of component design, extensive testing and improvement of manufacturing procedures, leading to the increase in development cost.To address this issue, active brake torque variation (BTV) compensation has been proposed for an electromechanical brake (EMB). The proposed compensator takes advantage of the EMB's powerful actuator, reasonably rigid transmission unit and high bandwidth tracking performance in achieving judder reduction.In a similar vein, recent advancements in hydraulic system design and control have improved the performance of hydraulic brakes on a par with the EMB, therefore invoking the possibility of incorporating the BTV compensation feature of the EMB within hydraulic brake hardware.In this paper, the typical characteristics of electromechanical and electro-hydraulic brake systems are presented. Based on the experimental results, the feasibility of active BTV compensation on the electro-hydraulic brake (EHB) systems is discussed. Furthermore,…
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Development of Three-Motor Electric Vehicle “EMIRAI 2 xEV”

SAE International Journal of Commercial Vehicles

Mitsubishi Electric Corporation-Kazuto Yokoyama, Masahiro Iezawa, Hideyuki Tanaka, Keiichi Enoki
  • Journal Article
  • 2015-01-1597
Published 2015-04-14 by SAE International in United States
Mitsubishi Electric has developed a concept car “EMIRAI 2 xEV” that features an electric vehicle (EV) powertrain for safe, comfortable, eco-friendly driving experiences in the future. The vehicle was exhibited during the 2013 Tokyo Motor Show and the 2014 Automotive Engineering Exposition. The xEV is a four-wheel-drive EV with three motors: a water-cooled front motor and two air-cooled rear motors with integrated inverters. The rear wheels can be driven independently. The degrees of freedom of the actuation can realize improved maneuverability and safety. The vehicle is also equipped with an onboard charger with a built-in step down DC/DC converter, an EV control unit, a battery management unit, and electric power steering. All of the instruments are developed by Mitsubishi Electric. Motion control systems for the xEV have been developed based on our proprietary motor control technology. In particular, this paper shows the design of three controllers: the high-precision traction control, the smooth G control, and the speed control. The effectiveness of the controllers is verified in simulations and driving experiments.
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Study on Stability Control of Electrical Vehicle Based on Regenerative Braking System

SAE International Journal of Commercial Vehicles

Changshu Institute of Technology-Qingzhang Chen
  • Journal Article
  • 2015-01-1565
Published 2015-04-14 by SAE International in United States
A regenerative braking system coordinated controller was developed for a front wheel drive BEV that also includes an ultra-capacitor storage system. This controller integrates the dual-motor regenerative braking with the hydraulic braking and stability control systems.The vehicle braking mode and the distribution of braking torque were determined according to the vehicle braking requirements, vehicle status and energy storage system (battery plus ultra-capacitor) state, and the stability control torque was provided according to the real-time vehicle stability condition. Simulation results show that, compared with a motor unilateral independence control strategy, the integrated coordinated controller improves the vehicle's stability when the vehicle corners while braking.
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Development of an Electric-based Power Steering System

SAE International Journal of Commercial Vehicles

Honda-Tomoya Ushimura
Honda R & D Americas Inc.-Scott Bradley Zagorski, James Post
  • Journal Article
  • 2015-01-1567
Published 2015-04-14 by SAE International in United States
In this research, a three degree-of-freedom (DOF) rack-type electric-based power steering (EPS) model is developed. The model is coupled with a three DOF vehicle model and includes EPS maps as well as non-linear attributes such as vibration and friction characteristics of the steering system. The model is simulated using Matlab's Simulink. The vibration levels are quantified using on-vehicle straight-line test data where strain-gauge transducers are placed in the tie-rod ends. Full vehicle kinematic and compliance tests are used to verify the total steering system stiffness levels. Frequency response tests are used to adjust tire cornering stiffness levels as well as the tire dynamic characteristics such that vehicle static gain and yaw natural frequency are achieved. On-center discrete sinusoidal on-vehicle tests are used to further validate the model. The validation of the model demonstrates that the interaction of the chassis and steering system can be considered during the early stages of vehicle development.
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Modeling, Analysis and Optimization of the Twist Beam Suspension System

SAE International Journal of Commercial Vehicles

FAW R&D Center-Jiaquan Chen, Min Qin, Yongfeng Jiang, Lingge Jin
Oakland University-Yin-Ping Chang
  • Journal Article
  • 2015-01-0623
Published 2015-04-14 by SAE International in United States
A twist beam rear suspension system is modeled, analyzed and optimized in this paper. An ADAMS model is established based on the REC (Rigid-Elastic Coupling) Theory, which is verified by FEM (Finite Element Method) approach, the effects of the geometric parameters on the twist beam suspension performance are investigated. In order to increase the calculation efficiency and improve the simulation accuracy, a neural network model and NSGA II (Non-dominated Sorting Genetic Algorithm II) are adopted to conduct a multi-objective optimization on a twist beam rear suspension system.
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Rubber Bushing Model for Vehicle Dynamics Performance Development that Considers Amplitude and Frequency Dependency

SAE International Journal of Commercial Vehicles

Honda R&D Americas Inc.-Koji Yamazaki
Honda R&D Co., Ltd.-Jun Nakahara, Yusuke Otaki
  • Journal Article
  • 2015-01-1579
Published 2015-04-14 by SAE International in United States
In many cars, ride is less comfortable on smooth roads. This is because when the hysteresis in the suspension components rises steeply, the increase of the equivalent spring constant at small amplitude deteriorates the vibration isolation of the suspension. Therefore suspension components should be designed to prevent a steep rises in hysteresis. Investigating the influence of hysteresis, component models, which can reproduce such hysteresis characteristics, should be installed with model parameters in the vehicle model. Using conventional methods, these parameters can be accurately identified if measurement data is provided; however, it is difficult at the earlier phase of vehicle development. Then, if conflicting performances, such as ride and handling, are to be improved, both should be considered concurrently as early in a phase of vehicle development as possible and the design specifications for suspension components should be determined to satisfy both performances. The simulations including ‘Multi-Body Simulation’ (MBS) should be performed using the same model with the same parameters. Furthermore, they should be done even if measurement data is not available. However, there is no…
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Perceptible Roll

SAE International Journal of Commercial Vehicles

Tata Motors Ltd.-Zubin Trivedi, Vivek Lakhera
  • Journal Article
  • 2015-01-1585
Published 2015-04-14 by SAE International in United States
In case of design of passenger vehicles, one of the priorities is how the dynamics behavior shall be perceived by the vehicle occupants. One of many such handling parameters is the vehicle body roll, which is usually quantified by the vehicle's Steady State Roll Gradient. This number gives an indication of the rotation of the vehicle body in response to unit lateral force acting on the vehicle, as in the case of cornering. However it does not necessarily indicate the roll as sensed by a person seated inside it.A study showed that the subjective feel is not entirely dependent on roll gradient. In some cases the occupant may feel more confident and comfortable in a vehicle with a relatively higher roll gradient, or vice versa. In such cases, designing for roll gradient alone may not serve the purpose of secure and comfortable feel. To account for this discrepancy, a study was carried out to quantify the motion felt by the occupant.It was found that the seating position is a vital element influencing the sensation generated…
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The Impact of Gear Meshing Nonlinearities on the Vehicle Launch Shudder

SAE International Journal of Commercial Vehicles

Tongji University-Guangqiang Wu, Wenbo Luan
  • Journal Article
  • 2015-01-0610
Published 2015-04-14 by SAE International in United States
During the launch of a car, severe torsional vibration sometimes may occur in its driveline due to somewhat the slipping of the clutch, its intuitive sense for an occupant is the longitudinal vibration of the vehicle, referred to as the launch shudder whose characteristic frequency is from 5 to 25 Hz generally. As the main vibration sources of the driveline and its crucial nonlinear components, the variable stiffness and backlash of the gear meshing are considered, their impacts on the launch shudder are analyzed in this paper.Conformal mapping, finite element method and regression method etc. are the main approaches to calculate the variable meshing stiffness of a gear pair. If this stiffness is get, it can usually be substituted for its approximate analytical expression, just with finite harmonic terms, in Fourier Series form into Ordinary Differential Equations(ODEs) to calculate the vehicle responses with its nonlinearity considered.There are two methods to model gear backlash, one is to introduce nonlinear backlash function to the stiffness matrix of the system, the other is to model and add restoring…
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