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Transient thermal behavior of dry clutch under non-uniform pressure condition

Shanghai Jiao Tong University-Yongchun Jin, Li Chen, Cheng Cheng
  • Technical Paper
  • 2020-01-1418
To be published on 2020-04-14 by SAE International in United States
Accuracy of thermal models is critical to clutch design in case of excessive temperatures due to large amounts of friction heat generated in the narrow space. Pressure distribution on the clutch friction interface is an important factor affecting heat flux distribution, thus affecting temperature distribution. But no previous literature reported how the pressure is distributed on dry clutches. This study conducts an experiment to obtain the pressure distribution for one typical dry clutch equipped with a set of diaphragm spring. Considering that the frictional interface is in contact, ordinary pressure sensors are not applicable because they have to separate the interface for a certain distance. Addressing this difficulty, this study makes use of pressure sensitive film and acquires data based on image processing techniques. Thereafter, a polynomial model with dimensionless parameters is developed to fit the pressure distribution. Thus, the non-uniform pressure model is worked out. After that, the proposed pressure model is applied to a thermal model based on finite element method. In addition, two conventional thermal models, which use uniform pressure and uniform…
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Modeling, Validation and Control Strategy Development of a Hybrid Super Sport Car based on Lithium Ion Capacitors

Automobili Lamborghini Spa-Riccardo Parenti, Maurizio Reggiani
University of Bologna-Alessandro Franceschi, Nicolo Cavina, Enrico Corti
  • Technical Paper
  • 2020-01-0442
To be published on 2020-04-14 by SAE International in United States
Today, the contribution of the transportation sector on greenhouse gases is evident. The fast consumption of fossil fuels and its impact on the environment have given a strong impetus to the development of vehicles with better fuel economy. Hybrid electric vehicles fit into this context with different targets, starting from the reduction of emissions and fuel consumption, but also for performance and comfort enhancement. Lamborghini has recently invested in the development of a hybrid super sport car, due to performance and comfort reasons. Aventador series gearbox is an Independent Shift Rod gearbox with a single clutch and during gear shifts, as all the single clutch gearbox do, it generates a torque gap. To avoid the additional weight of a Dual Clutch Transmission, a 48V Electric Motor has been connected to the wheels, in a P3 configuration, to fill the torque gap, and to habilitate regenerative braking and electric boost functions. This paper discusses the usage of a control-oriented vehicle and powertrain model to analyze the performance of the first Lithium Ion Capacitor-based hybrid V12 by…
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An LQR Approach of Automatic Transmission Upshift Control Including Use of Off-going Clutch within Inertia Phase

Ford Motor Company-Vladimir Ivanovic, Yijing Zhang, Yuji Fujii
University of Zagreb-Ivan Cvok, Josko Deur
  • Technical Paper
  • 2020-01-0970
To be published on 2020-04-14 by SAE International in United States
The paper first demonstrates, based on control trajectory optimization results, that using the off-going clutch during the inertia phase along with the main, oncoming clutch can improve the performance an automatic transmission (AT) upshift control in terms of faster and/or more comfortable shift, while sacrificing transmission efficiency and control simplicity to some extent. The use of linear quadratic regulation (LQR) in upshift control is beneficial from the standpoint of optimality of multi-input control action, and the possibility to set a trade-off between the aforementioned conflicting criteria. The proposed LQR cost function includes two conflicting criteria related to driving comfort and clutch thermal energy loss, while the third criterion related to shift duration is determined by imposing a linear profile of oncoming clutch slip-speed reference, shown to be nearly-optimal based on control trajectory optimization. A special emphasis is on proper implementation of nonlinear energy loss term through linear LQR cost function cross term and using a clipped optimal control approach to provide that the clutches (described as torque source elements) can only dissipate energy. The LQR…
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Testing of a wet plate clutch system for anti-shudder performance

Afton Chemical Corp.-Philippe Ezanno
BorgWarner Automotive-Jason Bares
  • Technical Paper
  • 2020-01-0560
To be published on 2020-04-14 by SAE International in United States
The wet clutch system ( WCS ) is a complex combination of friction plates, separator plates and lubricant. The basic function of the WCS is to transfer torque under various operating conditions such as slipping, shifting, start/launch and/or torque converter clutch operation. During these conditions the slope of the coefficient of friction versus slip speed ( µ-V ) curve must be positive to prevent shudder of the WCS. A test procedure is needed to evaluate the WCS over a durability duty cycle to monitor the µ-V curve slope and shudder potential. The clutch plates and fluid must be tested together and remain together during the test to evaluate as a WCS. The objective of this paper is to describe this new test procedure which builds on the basics of the SAE J2964 - Low Speed Continuous Slip µ-PVT test procedure but a duty cycle is added to age the WCS. The test includes measurement of the µ-V slope at several intervals during the test ( before break in, after break in, and after each 12…
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Volume of Fluid vs. Cavitation CFD-Models to Calculate Drag Torque in Multi-Plate Clutches

SIMERICS GmbH-Rudi Niedenthal
Technical University of Munich-Daniel Groetsch, Katharina Voelkel, Hermann Pflaum, Karsten Stahl
  • Technical Paper
  • 2020-01-0495
To be published on 2020-04-14 by SAE International in United States
Wet running multi-plate clutches and brakes are important components of modern powershift gearboxes and industrial powertrains. In the open stage, drag losses occur due to fluid shear. Identification of drag losses is possible by experiment or CFD-simulation. For calculation of the complex fluid flow of an open clutch CFD-approaches such as the Volume of Fluid (VoF) method or the Singhal cavitation model are applicable. Every method has its own specific characteristics. This contribution sets up CFD-calculation models for different clutches with diverse groove designs. We present results of calculations in various operating conditions obtained from the Singhal cavitation model and the VoF-method. Despite the high spatial resolution of the calculation models the usage of a modern commercial CFD-solver and mesher (Simerics MP+) results in very short calculation times. The developed CFD-models consider the geometry of a complete clearance consisting of the friction plate, the gap between the plates, the steel plate and the flow conditions arising from the design of the inner and outer plate carrier. The full 360-degree modeling makes it possible to take…
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A Comprehensive Study on the Challenges of Dual Mass Flywheel in Real-World Operating Conditions of the Indian Market

Mahindra & Mahindra Ltd-Vikraman Vellandi, Suresh Kumar Somarajan, Mohan Selvakumar Ganesh
  • Technical Paper
  • 2020-01-1014
To be published on 2020-04-14 by SAE International in United States
Dual mass flywheel (DMF) is widely used to isolate the drivetrain from the high torsional vibrations induced by the engine. While DMF can significantly improve the noise, vibration and harshness (NVH) characteristics of the vehicle, there are multiple challenges experienced in the real-world operating conditions when compared with the single mass flywheel (SMF). This paper explains the challenges of using DMF in a high power-density diesel powertrain for a multi-purpose vehicle (MPV) application in the Indian market. The gradient launch performance of the vehicle is compared for different gradients (6%, 8%, 12%, 18% and 28%) and the results confirmed that the slip time and launch energy of the DMF variant is ~50% higher than the SMF. Moreover, the DMF vehicle could be launched comfortably only upto 12% gradient whereas the SMF variant could negotiate upto 18% gradient easily. Furthermore, the higher launch energy requirement of the DMF is also responsible for a higher temperature of the clutch system by 33% as confirmed by the temperature measurements inside the clutch housing. The increased temperature poses a…
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Dual-mass flywheel with torque limiter: an effective solution for overtorque suppression in automotive transmission

Politecnico di Torino-Enrico Galvagno, Alessandro Vigliani, Giuseppe Calenda
  • Technical Paper
  • 2020-01-1016
To be published on 2020-04-14 by SAE International in United States
During some critical maneuvers, transmission systems using Dual Mass Flywheel (DMF) may experience overtorques, which could possibly lead to structural damages of the transmission components. A dual mass flywheel is essentially composed by two inertias: a primary mass connected to the engine and a secondary mass to the clutch. The torque delivered by the engine is transmitted through a drive plate and arc springs, the latter absorbing the torsional oscillations coming from internal combustion engine. This paper investigates overtorque issues that affect DMFs in automotive transmission and proposes a solution based on a torque limiter, consisting in a friction clutch inserted between the two masses. This device limits the maximum torque to a specific slipping value. Experimental analysis on a dedicated bench tested the durability of different friction pads and the variation of the slipping torque with time. The paper analyzes the torque limiter benefits through a detailed torsional model implemented in LMS Amesim. This model simulates the transmission torsional dynamics focusing on DMF with torque limiter; overtorque phenomenon are excited by choosing dedicated tests,…
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An Intuitive Derivation of the Dual-Clutch Model for Clutch Shift Dynamics

FCA US LLC-Pradeep Attibele
  • Technical Paper
  • 2020-01-0433
To be published on 2020-04-14 by SAE International in United States
There are several commercial off-the-shelf software available to study transmission and driveline dynamics. Many of these software require a faithful representation of the transmission topology in order to carry out the analyses. This approach utilizes several redundant degrees of freedom which may not be necessary for studying low frequency (<~30 Hz) dynamics and may be computationally inefficient. The dual-clutch model has been proposed as a generic 2-DOF model that overcomes some of these drawbacks. In this paper, the dual-clutch model is initially derived from first principles, starting with the equations of motion for a planetary automatic transmission. The model coefficients - the inertia matrix and the matrix of clutch gains - are then derived using a more intuitive approach and compared to the model derived from first principles.
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A Study on the Development of the CPA (Centrifugal Pendulum Absorber)Reducing the Rattle & Booming Noise in the Manual Transmission Vehicle

Ukjin Kim
  • Technical Paper
  • 2020-01-0397
To be published on 2020-04-14 by SAE International in United States
In recent years, the automotive engine strategies are forced on downsizing and down speeding to enhance fuel economy and reduce the emission. These make torque increase significantly in order to improve the vehicle performance, especially in diesel engines. At this time, the torsional damper performs the most important role in the driveline NVH of the manual transmission system. The clutch disk with torsional dampers is not easy to be applicable to the high torque of low speed RPM range. And DMF with sufficient isolation of vibrations of driving system includes disadvantages of the expensive cost, delayed response, and engine NVH aspect deteriorated due to increase of angular acceleration of engine. This paper presents that the Centrifugal Pendulum Absorber (CPA) is applied to maximize the isolation and to compensate for the disadvantages of DMF and SMF system. Furthermore, CPA was developed for the first time in the world on SMF clutch discs in manual transmission.
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Development and Demonstration of a New Range-Extension Hybrid Powertrain Concept

Tongji University-Zhiyu Han, Zhenkuo Wu, Xiaojie Gao, Yongzheng Sun, Runyu Ni, Jian Feng, Jian zhong, Xinbo Chen, Zhiguo Zhao, Zhuoping Yu
  • Technical Paper
  • 2020-01-0845
To be published on 2020-04-14 by SAE International in United States
A new range-extension hybrid powertrain concept, namely the Tongji Extended-range Hybrid Technology (TJEHT) was developed and demonstrated in this study. This hybrid system is composed of a direct-injection gasoline engine, a traction motor, an integrated starter-generator (ISG) motor, and a transmission. In addition, an electronically controlled clutch between the ISG motor and engine, and an electronically controlled synchronizer between the ISG motor and transmission are also employed in the transmission case. Hence, this system can provide six basic operating modes including the single-motor driving, dual-motor driving, serial driving, parallel driving, engine-only driving and regeneration mode depending on the engagement status of the clutch and synchronizer. Importantly, the unique dual-motor operation mode can improve vehicle acceleration performance and the overall operating efficiency. The hybrid system controls and energy management strategy based on equivalent fuel consumption minimization were developed and validated. The choice of an operating mode is optimized according to the drivers’ demand, actual vehicle state, operation conditions, and other boundary conditions. In this paper, the powertrain architecture and operating modes are firstly described. Secondly, the…