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Future hybrid Vehicles with advanced 48V electrified drive train technology to reduce Co2 emission

Mercedes-Benz R&D India Pvt Ltd.-Chandrakant Palve, Pushkaraj Tilak
  • Technical Paper
  • 2019-28-2487
To be published on 2019-11-21 by SAE International in United States
Future hybrid vehicles with advanced 48V electrified drive train technology to reduce CO2 emission. Chandrakant Palve* Pushkaraj Tilak * * Mercedes-Benz Research & Development India Pvt. Ltd. Bangalore. India. Key Words: 48V, CO2, P3 Hybrid, Electrified powertrain, AMT, emission, shift comfort, motor Research and/or Engineering Questions/Objective Global automotive industry is putting effort in moving from conventional powertrain technology to hybrid & electric powertrains. This efforts plays a vital role to achieve cleaner environment, improved performance, reduced fossil-fuel dependency, low noise for meeting regulatory & customer requirements. Automotive industry is facing a challenge of meeting stringent CO2 emission targets of 95g & 175g per kilometer for passenger cars & light commercial vehicles respectively. 48V is an important stepping stone in this direction. By taking motivation from this strategic challenge, advanced 48V P3 electrified powertrain technology has been proposed. The objective of this research is a novel electrified powertrain which offers Dual Clutch Transmission (DCT) level of shift comfort in combine with CO2 benefit without additional cost and weight penalty. Methodology The present study describes a unique…
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Dual Clutch Transmission Vibrations during Gear Shift: A Simulation-Based Approach for Clunking Noise Assessment

Politecnico di Torino-Enrico Galvagno, Luca Dimauro, Gianluca Mari, Mauro Velardocchia, Angelo Domenico Vella
Published 2019-06-05 by SAE International in United States
A novel methodology, for the assessment of Dual Clutch Transmission vibrations during gear shifts, is proposed in this paper. It is based on the capability to predict through numerical simulation a typical dynamic quantity used to objectively evaluate the vibrational behavior of a gearbox during experimental tests, i.e. the acceleration of a point on the external surface of the gearbox housing. To achieve this result, a two-step approach is proposed: an accurate simulation of the internal transmission dynamics and an offline uncoupled computation of the gearbox housing acceleration from the output of the simulation. The first step required the definition of a suitable nonlinear lumped parameter model of the car equipped with a DCT that was implemented in Amesim software. The second step, developed as a post processing tool in Matlab, is based on the knowledge of the inertance Frequency Response Functions (FRFs) between a single component of force applied in a bearing and a single component of acceleration in the measurement point. The indices used to assess the clunk severity are peak to peak…
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Model Based Control of Synchronizers for Reducing Impacts during Sleeve to Gear Engagement

CEVT China Euro Vehicle Technology-Eva Barrientos, Henrique Budacs, Johan Hellsing
Chalmers University of Technology-Anders Grauers
Published 2019-04-02 by SAE International in United States
This paper presents a model based control strategy aimed to reduce noise and wear during gearshifts in conventional and hybrid Dual Clutch Transmissions (DCT and DCTH) and Automated Manual Transmissions (AMT). The control strategy is based on a newly developed dog teeth position sensor layout at China Euro Vehicle Technology AB (CEVT), a detailed simulation model for gear engagement and already existing speed sensors in the transmission. The details of dog teeth position sensor and simulation model are also presented in this paper. During gear shifting, noise is generated because of impacts between the sleeve teeth and the idler gear dog teeth after speed synchronization. Besides noise, these impacts are also responsible for delaying the completion of shift and contribute to wear in the dog teeth, hence reducing the lifespan of the transmission. The simulation model for gear engagement can simulate these impacts. Based on the simulation model and optimal control theory, an ideal dog teeth position trajectory is formulated that avoids the impact between sleeve and idler gear dog teeth, before the start of…
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In-Gear Slip Control Strategy of Dry-Clutch Systems Using a Sliding Mode Control

Hyundai Motor Co.-Jinsung Kim, Juhyun Nam
Published 2019-04-02 by SAE International in United States
This paper proposes a clutch control strategy during in-gear driving situations for Dual Clutch Transmissions (DCTs). The clutch is intentionally controlled to make small amount of a slip to identify the torque transfer capacity. The control objective of this phase is to ensure the clutch slip fairly remaining the specified value. To achieve this, the micro-slip controller is designed based on sliding mode control theory. Experimental verifications performed on onboard control system of the DCT equipped vehicle demonstrate that the proposed controller good tracking performance of the desired slip speed.
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Control Strategy and Energy Recovery Potential for P2 Parallel Hybrid Step Gear Automatic Transmissions

Michigan Technological University-Darrell Robinette, Joshua Orlando
Published 2019-04-02 by SAE International in United States
The purpose of this investigation is to present a control strategy and energy recovery potential for P2 parallel hybrid step gear automatic transmissions. The automatic transmission types considered for the investigation are rear wheel drive 8 speed dual clutch transmission and 8 speed planetary automatic equipped each equipped with an electric motor between the engine and transmission. The governing equations of clutch-to-clutch upshift controls are presented and are identical for each transmission type. Various strategies are explored for executing the upshift under a range of input torques, shift times and engine torque management approaches. The differences in energy recovery potential based upon control strategy is explored piecewise as well as through a DFSS study. On a comprehensive drive cycle consisting of FTP 75, US06 and HWFET test cycles, it is shown that upshift regen torque management can be equivalent to approximately 0.8% of the total fuel energy used. Additionally, it is shown that the utilization of the P2 electric motor is a further enabler to reduced shift times and improved shift quality at part throttle…
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Design and Analysis of a Novel Magnetorheological Fluid Dual Clutch for Electric Vehicle Transmission

Shanghai Jiao Tong University-Yafei Wang
University of Wollongong-Huan Zhang, Haiping Du, Shuaishuai Sun, Weihua Li
Published 2019-02-18 by SAE International in United States
A novel magnetorheological fluid dual clutch (MRFDC) for electric vehicle transmission is proposed in this article. The structure was based on the MR fluid clutch and traditional dual clutch equipped on internal combustion engine vehicle. Therefore the MRFDC combines the advantages of MR fluid clutch and dual clutch transmission (DCT) to achieve high control accuracy and fast response. The structure of MRFDC was designed by Unigraphics (UG) three-dimensional (3D) modeling software. Then, finite element analysis (FEA) for magnetic field was conducted by ANSYS under different applied currents from 0.1A to 1A with 0.1A space to obtain the relation between the applied current and magnetic field. In this article, Herschel-Bulkley model is used to predict the MR fluid behavior because of the high shear rate of MR fluid. Finally, output torque of MRFDC can be estimated by calculus with geometric dimensions of MRFDC structure and rheological properties of MR fluid dependent on the magnetic field generated by the applied current. Finally the relation between the applied current and output torque of the internal clutch and external…
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A Guide to Handle Dry DCT (Dual Clutch Transmission) Motor

Hyundai Autron-Jeehoon Kim, Seonmi Han, Seungman Choi
Infineon Technologies Korea-Haram Kim
Published 2018-04-03 by SAE International in United States
These days, the usage of Dual Clutch Transmission (DCT) system is increasing in the transmission systems according to Strategy Analytics [1]. The reason is mainly due to its quicker and smoother transition of gear shifting than conventional single clutched transmissions. Among two main types of DCTs, dry DCT is more beneficial in reducing fuel consumption than wet DCT due to the lack of hydraulic structure. However, dry DCT requires highly precise control due to its mechanical structure. Therefore, the main focus in this paper will be on dry DCT as the main idea of this paper was found during developing its particular control algorithm. Due to this reason, where DCT is mentioned later in this paper, it means “dry” type of DCT.When a conventional hydraulic automatic transmission with single clutch fails, the system simply locks at the third speed gear mechanically. However, the failure modes can vary numerously in DCT systems where several moving parts should be controlled simultaneously. However, in the authors’ opinion, the current criteria of failure mode detection are so broad that…
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A Development of Fuel Saving Driving Technique for Parallel HEV

Hyundai Motor Company-Jeong Soo Eo, Sung Jae Kim, Jiwon Oh, Yeon Kwang Chung, Young Joon Chang
Published 2018-04-03 by SAE International in United States
This paper examines the effect of pulse-and-glide (PnG) driving strategies on the fuel efficiency when applied on parallel HEVs. Several PnG strategies are proposed, and these include the electrical, mechanical, and combined PnG strategies. The electrical PnG strategy denotes the hybrid powertrain control tactics in which the battery is charged or discharged according to the power demanded while maintaining the constant vehicle speed. On the other hand, the mechanical PnG strategy denotes the powertrain control tactics in which the vehicle accelerates or decelerates according to the power load while minimizing the battery usage. The combined PnG strategy involves both electrical and mechanical strategies to find a balanced point in between them. Here, a tradeoff relationship between the fuel efficiency and the vehicle drivability related to the tracking performance of the desired target speed is revealed. In the assessment of the feasibility of applying each of the formerly mentioned hybrid driving strategies, the causes of driveline heat loss are recorded and analyzed by their types. These include the engine heat loss, engine friction loss, motor loss,…
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Lubricant Technology for Hybrid Electric Automatic Transmissions

Lubrizol Corp.-Michael P Gahagan
Published 2017-10-08 by SAE International in United States
The automotive vehicle market has seen an increase in the number of hybrid electric vehicles (HEVs), and forecasts predict additional growth. In HEVs, the hybrid drivetrain hardware can combine electric motor, clutches, gearbox, electro-hydraulics and the control unit. In HEV hardware the transmission fluid can be designed to be in contact with an integrated electric motor. One transmission type well-suited to such hybridization is the increasingly utilized dual clutch transmission (DCT), where a lubricating fluid is in contact with the complete motor assembly as well as the DCT driveline architecture. This includes its electrical components and therefore raises questions around the suitability of standard transmission fluids in such an application. This in turn drives the need for further understanding of fluid electrical properties in addition to the more usually studied engineering hardware electrical properties. New understanding around the properties of transmission fluids in electric fields has been gained. This knowledge has been used to design a fluid with the appropriate electrical characteristics coupled with those essential performance characteristics for a fluid required to lubricate a…
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A Theoretical Investigation of the Influence of Powertrain Mounts on Transmission Torsional Dynamics

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Politecnico di Torino-Enrico Galvagno, Pablo Gutierrez, Mauro Velardocchia, Alessandro Vigliani
  • Journal Article
  • 2017-01-1124
Published 2017-03-28 by SAE International in United States
This paper investigates the effect of the powertrain mounting system on the linear and nonlinear torsional dynamical behaviour of a transmission system. To this aim, two dynamic models, one with rigid mounts and the other with flexible mounts, are presented and compared: the first model considers only the torsional dynamics of transmission and driveline, while the second model includes also a 3 degrees-of-freedom powertrain block. The mechanical coupling and interaction between the powertrain block and transmission system is discussed and formulated. These models are then analyzed in terms of vibrational mode shapes, natural frequencies and Frequency Response Functions (FRFs); a sensitivity analysis of the main transmission parameters, e.g. the gear ratio, is also presented. From the comparison of the two simulated configurations (with and without powertrain mounts) both in time and frequency domain, a significant interaction between the two subsystems is noticed, particularly in the vehicle acceleration signal. Neglecting the powertrain mounts may lead to underestimating the real vibration level. A nonlinear model of a dual clutch transmission, including the main backlashes present along the…
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