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Two-Speed Transmission Gear Shift Process Analysis and Optimization Using Genetic Algorithm

SAE International Journal of Alternative Powertrains

China-Zhan Cao
China Automotive Technology and Research Center Co., Ltd., China-Jiansen Yang, Xinyu Wang
  • Journal Article
  • 08-09-01-0001
Published 2020-01-16 by SAE International in United States
Electric Vehicle (EV) equipped with two-speed transmission has benefit in improving dynamic performance and saving battery consumption. However, during gear shift process, torque interruption and shift impact may lead to a bad shift quality. This work investigates gear shift process in an Automated Manual Transmission (AMT) configuration-based two-speed transmission. First of all, a typical gear shift process is analyzed. Parameters like motor speed, shift force, motor torque change rate, and speed difference between synchronizer and target engage gear are all included to find the relationships with shift duration. Then vehicle jerk is introduced as a criterion to evaluate shift impact. Besides, a comprehensive shift control strategy is developed. While keeping the output torque at wheels unchanged, the shift strategy also improved motor working efficiency after gear shift. Therefore, to determine an optimum shift strategy and achieve a balance among different parameters, Genetic Algorithm (GA) multi-objective optimization method is implemented. Through GA optimization, several solutions are presented and discussed. The final results can well satisfy the requirements of different objectives. This work provides a novel and…
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Band gaps and torsional vibration in a periodic shaft

EATON Ltda.,-André L. A. M. Leão
University of Campinas-J. R. F. Arruda
  • Technical Paper
  • 2019-36-0224
Published 2020-01-13 by SAE International in United States
Shafts used in torque and angular velocity transmission may behave as torsional vibration amplifiers due to resonance followed by unwanted vibrations. Many technologies are applied to attenuate vibration in certain frequency ranges in automotive, aerospace and industrial applications. More recently, using the concept of periodic structures (phononic crystals and metamaterials), it has been shown to be possible to obtain frequency band gaps where elastic waves cannot propagate and, therefore, standing waves cannot build up, thus avoiding resonance. Using a few periodic cells large attenuation can be obtained, so that the structure behaves like a mechanical filter. Investigations in periodic structure dynamics have been developed in recent years aiming at to attenuating specific and wide frequency ranges. The periodic structure can be a combination of different materials, or a unique material varying the geometry periodically. This work explores the possibility of using periodic shaft structures to create torsional band gaps for torsional vibration attenuation. Theoretical models and experimental results for torsional vibrations in a periodic shaft are investigated. The approach is to build a dynamic model…
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Methodology using IPS for creation and installation of flexible components in stationary vehicles

General Motors, do Brasil-André Tognolli, Fernando Utiyke, Douglas Migliorini
  • Technical Paper
  • 2019-36-0125
Published 2020-01-13 by SAE International in United States
Through dynamic computational simulations it is possible to achieve a high reliability index in the development of automotive components, thus reducing the time and cost of the component can generate considerable levels of competitiveness and quality.This work suggests the validation of a methodology to create the virtual routes to find the best design of the flexible components influenced by force of gravity, thermal expansion or even the static balance between the anchor points and used to be designed and installed in the vehicle always in the nominal condition which in many cases diverge from the physical.With the difficulty of predicting mathematically the nonlinear relations of deformation and motion under the effect of forces and moments, we use the NX9 software in the creation of the dynamic movement motion to the motor and transmission assembly imposes on the flexible components through a routine mapped by Cartesian coordinates, simulating the characteristic movements of the vehicle in normal working situations.Using the software IPS - Industrial Path Solution, for the construction of the flexible model to be simulated, the…
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Effects of Engine Speed on the Performance at Extreme Vehicle Driving Conditions

FCA LATAM, Universidade Federal de Minas Gerais-Fabrício Thomaz, José Guilherme Coelho Baeta
  • Technical Paper
  • 2019-36-0297
Published 2020-01-13 by SAE International in United States
Nowadays, improvements in engine fuel economy and reduction in pollutant emissions have been much discussed. Downsizing and downspeeding are methods widely used in the automotive market, used to increase internal combustion engine efficiency. Fuel consumption is commonly measured through a specific cycle that could differ between countries. Federal Test Procedure (FTP-75) for Latin America and New European Driving Cycle (NEDC) for Europe are some examples. These cycles include normal driving conditions, low vehicle load and mild environmental conditions. The style of gear shifting is one of the main factors affecting fuel efficiency and performance of motor vehicles. At extreme diving conditions, parameters like coolant and air charge temperature could reach limit durability values of the system. In order to avoid knocking and maintain structural reliability, it becomes mandatory to control the engine speed. An increase in engine speed reduces engine load requirements and thus, turbocharger loads. Lower turbocharger requirements reduce ACT and, consequently, reduce knocking. This process allows an advanced ignition timing, enabling more chamber pressure and improving fuel conversion efficiency. However, a higher engine…
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Powertrain Hardware In The Loop X Vehicle Hardware In the Loop: How to Optimize Their Use During the Software Development Cycle

FCA - Fiat Chrysler Automotive-Jeeves Lopes dos Santos, Elaine Cristina Guglielmoni Silva, Cleber Albert Moreira Marques, Gustavo Maximo Urquiza de Sá, José Henrique Silva, Mauricio Vianna de Resende
  • Technical Paper
  • 2019-36-0311
Published 2020-01-13 by SAE International in United States
The advance of technology and the demand for new features on vehicles has been challenging the automotive industry to find ways to speed up its development process, while increases the robustness and quality of its products. On this context, the embedded software development for vehicles has been directly impacted. In other words, the number of Electronic Control Units (ECUs) considerably increased on the past few years and the number of lines of code, as well as their complexity, have been exponentially increased. In order to deal with this new reality, besides the automotive test prototypes used during the development, the automotive industry has been using different virtual environment to develop, verify and validate its products. As an example, we can see an increase in the use of different Hardware In The Loop system architectures (HILs) such as Powertrain HIL (with real Engine and Transmission Control Modules - ECM and TCM) and Vehicle HILs (with real ECM, TCM, several other ECUs, and also several electronic components that composes the vehicle). Each of these options has its…
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A proposal for semi-analytical model of teeth contact with application to gear dynamics

Politecnico di Torino, Department of Mechanical and Aerospac-Carlo Rosso, Fabio Bruzzone, Tommaso Maggi, Claudio Marcellini
  • Technical Paper
  • 2019-01-2269
Published 2019-12-19 by SAE International in United States
In this paper a semi-analytical (SA) algorithm developed for the solution of the contact problem between two mating spur gears is presented and its application to the study of engagement dynamics is shown. Firstly, a quasi-static two-dimensional (2-D) approach is implemented to solve the contact taking into account several flexibility contributions related to the mating gears. In detail, a modified Hertzian model for the investigation of the real contact area considering the variable curvature of the profiles is developed. A comparison between this model and the classical Hertzian model is shown: the limitations of the classical method, for instance the possibility of analyzing bodies with varying curvatures and the peaks of pressure due to corner contact are therefore overcome. Furthermore, all the different tooth and gear deformations due to the meshing interaction are shown. This allows the computation of the Static Transmission Error (STE), main source of vibration and noise. The influence of tooth profile modifications is also highlighted. A comparison of the calculation of the STE with a Finite Element Method (FEM) model and…
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Prediction of Friction Durability in Off-Road Applications Based on Mechanistic Understanding of the Effects of Fluids and Surfaces on Clutch Friction

Afton Chemical Corporation-Mark Devlin, Atanu Adhvaryu
Komatsu Ltd.-Shinpei Kariwa, Toshiharu Abekawa
  • Technical Paper
  • 2019-01-2339
Published 2019-12-19 by SAE International in United States
After new transmission lubricants are developed there is an extensive validation program where friction durability testing is performed on multiple clutch materials. Each durability test can run for long terms and the entire validation program can take much longer terms. A well designed lubricant and friction material will deliver the necessary friction control for construction equipment to operate at optimum level. A mechanistic construct has been evaluated to calculate friction durability in clutch systems based on fluid and surface tribological properties. Fluid properties include both boundary frictional and rheological effects. Surface properties include elastic modulus, surface roughness, asperity density and asperity tip radius. Using this mechanistic construct friction durability has been predicted. In the past, researchers in the field have often associated lubricant induced glazing of the friction material surface as the cause of the loss of friction control in clutch systems. In the current study, results show that wear is also a dominant cause of friction loss. In short clutch friction tests the rate of change in surface properties and fluid properties have been…
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Art of fuel economy lubricant formulation: How appropriate fuel economy assessment tools and new technologies are opening-up new formulation spaces for the next generation fuel economy lubricants

Infineum Japan Ltd.-Tsuyoshi Matsui
Infineum UK Ltd.-Thomas Featherstone, Peter Wright
  • Technical Paper
  • 2019-01-2242
Published 2019-12-19 by SAE International in United States
Designing fuel economy lubricants is an art; finding the right balance between fuel economy and durability requirements is complex, with many trade-offs. To open new formulation spaces with ever increasing fuel economy, a deep understanding of how lubricating oils respond to different drive cycles, engine/transmission type and any coating properties, e.g. DLC, is required.In this paper, we describe how the implementation of WLTC requires lubricant optimization to deliver improved fuel economy under this test cycle and therefore, lubricant viscosity reduction becomes more important. We also illustrate optimization of the sludge system is key to reducing overall viscosity of lubricants for ultra low viscosity application, such as in SAE 0W- 8 viscosity grade oils. To meet the cleanliness challenges in an SAE 0W-8 environment, we describe a developmental sludge handling system with improved cleanliness at constant viscosity to conventional SAE 0W-8 lubricants. A SAE 0W-8 demonstration oil with the developmental sludge handling system at equivalent sludge handling to a conventional system showed lower viscosity properties and demonstrated improved fuel economy performance in a motored rig test…
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Harness Model Development by co-simulation of the Transmission Black Box model and Vehicle model for a Medium Heavy Duty Internal Combustion based Powertrain

Isuzu Technical Center of America-Aishwarya Shetty, Santhosh Pasupathi, Bruce Vernham, Gerald Bergsieker
  • Technical Paper
  • 2019-01-2268
Published 2019-12-19 by SAE International in United States
With the automotive industry moving toward model based development approach, detailed model integration plays an important role in the process. In comparison to map-based models, detailed models have higher fidelity with the results being more accurate & repeatable. High fidelity models are significant as it allows for early design validation through experimentation. The primary objective of this study is to develop a co-simulation between the transmission black box in Simulink and the vehicle model in GT-Suite. The secondary objective of this study is to understand the difference in the fidelity of the map based transmission model and the detailed transmission model. For the detailed transmission model, the transmission black box provided by the supplier, is a comprehensive model setup in the Simulink platform. The co-simulation is initialized from Simulink, where in Simulink acts as the primary platform. The commands are then forwarded to GT-Suite which is embedded in the Simulink environment as an S-function. The co-simulated model has been validated against the data from the field testing. On comparison with the map based transmission model,…
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Reducing winter range loss for electric trucks

SAE Truck & Off-Highway Engineering: December 2019

Paul Weissler
  • Magazine Article
  • 19TOFHP12_02
Published 2019-12-01 by SAE International in United States

Researchers at the Austrian Institute of Technology have developed an air exchange system that's capable of reducing heat load by 37% in real-world tests.

Battery-electric vehicle (BEV) range loss from winter use of PTC (positive temperature coefficient) heating has become a source of major concern as the industry works to make EVs a mainstream choice. Addressing this particular problem area with an economically viable solution was deemed a worthwhile effort by the Austrian Institute of Technology (AIT), which is jointly owned by the Austrian government and the Federation of Austrian Industries. A fleet test of electric delivery trucks is underway on European roads.

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