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Fuel efficiency improvement in automatic Transmissions by Lock-up clutch slip control methodology.

Mahindra & Mahindra, Ltd.-Arun Sukumar
  • Technical Paper
  • 2019-28-0029
To be published on 2019-10-11 by SAE International in United States
Introduction :- Nowdays, Automatic transmissions (AT) have taken over more in the automotive market. Because of traffic, frequently clutch pedal pressing and shift lever operation becomes annoyance in manual transmission.Automatic Transmissions (AT) has better driving comfort, simple operation, but a lower transmission efficiency, higher fuel consumption, can't be competed with manual transmissions. Fuel economy of Automatic Transmissions is poor especially in city drive (Because of driving @ low engine speeds where Torque Converter(TC) is opened). Objective :- The objective of this paper is to present a methodology for torque converter clutches (TCC) to enable clutch slip control at low engine speeds in torque converter without adversely affecting noise and vibration (N&V) performance and increasing fuel economy. The effect of gear state, torque converter slip and power delivered to the driveline on fuel economy are to be discussed. Lock-Up Slip Schedule Determination:- A reasonable slip control area is choosen for achieving increase in transmission efficiency, fuel economy and isolation of torsional vibration. 1. Running in first gear, the torque converter clutch must be unlocked to obtain…

A Novel Heating-Coating Hybrid Strategy for Wind Turbine Icing Mitigation

Iowa State University-Linyue Gao, Liqun Ma, Yang Liu, Hui Hu
Published 2019-06-10 by SAE International in United States
The electro-thermal method is most commonly used for wind turbine anti-/de-icing. The upmost drawback of such systems is the high power consumption. In the present study, we proposed to use a durable slippery liquid-infused porous surface (SLIPS) to effectively reduce the power requirement of the heating element during the anti-/de-icing process. The explorative study was conducted in the Icing Research Tunnel at Iowa State University (ISU-IRT) with a DU91-W2-250 wind turbine blade model exposed under severe icing conditions. During the experiments, while a high-speed imaging system was used to record the dynamic ice accretion process, an infrared (IR) thermal imaging system was also utilized to achieve the simultaneous surface temperature measurements over the test model. In comparison to the traditional electrical heating strategies to brutally heat massive area of entire turbine blades, a novel heating-coating hybrid strategy, i.e., combining a leading-edge (LE) heating element to cover the first 30% of the chord length (C) along with using SLIPS to coat entire blade surface, was found to be able to keep the entire blade surface completely…
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An Experimental Investigation of a Wind-Driven Water Droplet over the Slippery Liquid Infused Porous Surface

Iowa State University-Liqun Ma, Hui Hu
Published 2019-06-10 by SAE International in United States
The promising anti-icing performance of the slippery liquid infused porous surface (SLIPS) has been recently demonstrated for various engineering applications. The runback icing for aircraft and wind turbines could be effectively mitigated considering the timely removal of water droplet by the wind shearing force due to the low adhesion on the SLIPS. In this study, the flow field both inside and around the wind-driven droplet over the SLIPS was experimentally investigated by using Particle Image Velocimetry (PIV) technique. Previous studies majorly focus on the internal flow pattern before the droplet incipient motion. In this study, the flow field inside a moving droplet was firstly investigated. As a result of the low surface adhesion of the SLIPS, droplet oscillations were eliminated and the droplet internal flow field could be corrected from the optical distortion. Besides the discussion on the wind speed, the droplet viscosity was also studied by varying the water concentration of the glycerin-water solution. It was found that the internal circulation was highly related with the droplet viscosity. The inner circulations within the water…
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An Experimental Study to Evaluate the Droplet Impinging Erosion Characteristics of an Icephobic, Elastic Soft Surface

Iowa State University-Liqun Ma, Zichen Zhang, Yang Liu, Hui Hu
Published 2019-06-10 by SAE International in United States
Elastic soft material/surface, such as Polydimethylsiloxane (PDMS), is a perspective, useful and low-cost hydrophobic and icephobic coating. While it has been reported to have good mechanical durability, its erosion durability under the high impacting of water droplets pertinent to aircraft inflight icing phenomena has not been explored. In this study, the droplet imping erosion characteristics of an icephobic PDMS surface/material is evaluated systematically upon the dynamic impinging of water droplets at different impact velocities (~ up to 75m/s), in comparison with other state-of-the-art icephobic materials/surfaces, such as superhydrophobic surface (SHS) and slippery liquid-infused porous surface (SLIPS). Surprisingly, the contact angle (CA) of the elastic PDMS is shown to have an over 20° increase (from 105° to 128°), which represents better hydrophobicity, after the erosion test which is mainly contributed to the higher roughness of the eroded PDMS surface. As for the icephobicity evaluation, intact PDMS was found to has ultra-low ice adhesion (~8 kPa), in comparison with SHS (i.e., ~100kPa) and SLIPS (i.e., ~35kPa). PDMS also shows outstandingly stable ice adhesion during the erosion test…
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Understanding the Stick Slip Behavior of Plastics and Target Setting: An OEM Perspective

Mahindra & Mahindra, Ltd.-Sundaralingam Somasundharam, Amit Kumar, Riyazuddin Mohammed, Prasath Raghavendran
Published 2019-06-05 by SAE International in United States
Automotive OEMs are aggressively using different materials for interiors due to value proposition and variety of options available for customers in market. Excessive usage of different grade plastics with zero gap philosophy can cause stick slip effect leading to squeak noise. Even though systems and subsystems are designed using best practices of structural design and manufacturing tolerances, extreme environmental conditions can induce contacts leading to squeak noise. Appropriate selection of interface material pairs can minimize the possibilities of squeak conditions. Stick-slip behavior of different plastics is discussed in the present study, along with critical parameters during material compatibility testing in a tribological test stand. Friction coefficient of different material pairs for a defined normal load and sliding velocity are analyzed for patterns to recognize squeaks versus time. An OEM perspective is presented with focus on material selection using objective metrics like coefficient of friction and set targets for raw material suppliers regarding compatible materials. In the next step, an algorithm based on machine learning approach has been developed for estimating stick-slip performance.
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Distributed Drive Electric Vehicle Longitudinal Velocity Estimation with Adaptive Kalman Filter: Theory and Experiment

China Automotive Engineering Research Institute Co., Ltd.-Yaming Zhang
Tongji University-Bo Leng, Lu Xiong, Zhuoping Yu, Dequan Zeng
Published 2019-04-02 by SAE International in United States
Velocity is one of the most important inputs of active safety systems such as ABS, TCS, ESC, ACC, AEB et al. In a distributed drive electric vehicle equipped with four in-wheel motors, velocity is hard to obtain due to all-wheel drive, especially in wheel slipping conditions. This paper focus on longitudinal velocity estimation of the distributed drive electric vehicle. Firstly, a basic longitudinal velocity estimation method is built based on a typical Kalman filter, where four wheel speeds obtained by wheel speed sensors constitute an observation variable and the longitudinal acceleration measured by an inertia moment unit is chosen as input variable. In simulations, the typical Kalman filter show good results when no wheel slips; when one or more wheels slip, the typical Kalman filter with constant covariance matrices does not work well. Therefore, a gain matrix adjusting Kalman filter which can detect the wheel slip and cope with that is proposed. Simulations are carried out in different conditions, including no wheel slips, one wheel slips, all wheel slip, passing a bump, and variable acceleration…
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Extended Kalman Filter Based Road Friction Coefficient Estimation and Experimental Verification

APTIV PLC-Bin Li, Guobiao Song
Ford Motor Co., Ltd.-Arlene Fang
Published 2019-04-02 by SAE International in United States
Accurate road friction coefficient is crucial for the proper functioning of active chassis control systems. However, road friction coefficient is difficult to be measured directly. Using the available onboard sensors, a model-based Extended Kalman filter (EKF) algorithm is proposed in this paper to estimate road friction coefficient. In the development of estimation algorithm, vehicle motion states such as sideslip angle, yaw rate and vehicle speed are first estimated. Then, road friction coefficient estimator is designed using nonlinear vehicle model together with the pre-estimated vehicle motion states. The proposed estimation algorithm is validated by both simulations and tests on a scaled model vehicle.
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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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Estimation of Side Slip Angle Interacting Multiple Bicycle Models Approach for Vehicle Stability Control

Andong National University-Bongchoon Jang
Chassis R&D-Youngjin Hyun
Published 2019-04-02 by SAE International in United States
This paper presents an Interacting Multiple Model (IMM) based side slip angle estimation method to estimate side slip angle under various road conditions for vehicle stability control. Knowledge of the side slip angle is essential enhancing vehicle handling and stability. For the estimation of the side slip angles in previous researches, prior knowledge of tire parameters and road conditions have been employed, and sometimes additional sensors have been needed. These prior knowledge and additional sensors, however, necessitates many efforts and make an application of the estimation algorithm difficult. In this paper, side slip angle has been estimated using on-board vehicle sensors such as yaw rate and lateral acceleration sensors. The proposed estimation algorithm integrates the estimates from multiple Kalman filters based on the multiple models with different parameter set. The IMM approach enables a side slip angle estimation from originally equipped vehicle sensors without prior knowledge of tire and road. The proposed estimation algorithm is evaluated via vehicle tests in electronic control unit level. The results have shown that the proposed estimator can successfully estimate…
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A Computational Study of Crystal Orientation Effects on High Strain Rate Performance of Single Crystal Copper

Mississippi State University-Yucheng Liu, Yangqing Dou
Published 2019-04-02 by SAE International in United States
This paper presents a computational study to investigate effects of crystal orientations on plasticity and damage of copper crystal at atomic scale. In the present study, a single crystal copper model was created as a target, which was struck and penetrated by a single crystal nickel. Three orientations, single slip system [1 0 1, 1 2 -1, -1 1 1], double slip system [1 1 2, 1 1 0, 1 1 -1], and octal slip system [1 0 0, 0 1 0, 0 0 1], were applied to the copper crystal. Their effects on plasticity and damage behavior of the single crystal copper were studied and compared using molecular dynamics simulations. Modified Embedded Atom Method potentials were applied to determine the pair interactions between the copper and nickel atoms.
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