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A Reverse Engineering Method for Powertrain Parameters Characterization Applied to a P2 Plug-In Hybrid Electric Vehicle with Automatic Transmission

FEV Group GmbH-Alessandro Perazzo
Politecnico di Torino-Enrico Galvagno, Federico Millo, Giuseppe DiPierro, Mauro Velardocchia, Gianluca Mari
  • Technical Paper
  • 2020-37-0021
To be published on 2020-06-23 by SAE International in United States
Over the next decade, CO2 legislation will be more demanding and the automotive industry has seen in vehicle electrification a possible solution. This has led to an increasing need for advanced powertrain systems and systematic model-based control approaches, along with additional complexity. This represents a serious challenge for all the OEMs. This paper describes a novel reverse engineering methodology developed to estimate relevant but unknown powertrain data required for fuel consumption-oriented hybrid electric vehicle modelling. The main estimated quantities include high-voltage battery internal resistance, electric motor and transmission efficiency maps, torque converter and lock-up clutch operating maps, internal combustion engine and electric motor mass moment of inertia, and finally front/rear brake torque distribution. This activity introduces a list of limited and dedicated experimental tests, carried out both on road and on a chassis dynamometer, aiming at powertrain characterization thanks to a suitable post-processing algorithm. In this regard, the methodology was tested on a P2 architecture Diesel Plug-in HEV equipped with a 9-speed AT. voltage and current sensors are used to measure the electrical power exchanged…
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On Prediction of Automotive Clutch Torsional Vibrations

Theofilos Gkinis PhD
Loughborough Univ-Homer Rahnejat
  • Technical Paper
  • 2020-01-1508
To be published on 2020-06-03 by SAE International in United States
Automotive clutches are prone to rigid body torsional vibrations during engagement, a phenomenon referred to as take-up judder. This is also accompanied by fore and aft vehicle motions. Aside from driver behaviour in sudden release of clutch pedal (resulting in loss of clamp load), and type and state of friction lining material, the interfacial slip speed and contact temperature can significantly affect the propensity of clutch to judder. The ability to accurately predict the judder phenomenon relies significantly on the determination of operational frictional characteristics of the clutch lining material. This is dependent upon contact pressure, temperature and interfacial slip speed. The current study investigates the ability to predict clutch judder vibration with the degree of complexity of the torsional dynamics model. For this purpose, the results from a four and nine degrees of freedom dynamics models are compared and discussed. Subsequently, the predictions are compared with the acquired data from an automotive driveline test rig. It is shown that the complexity of the dynamic model, intended for the study of a clutch system, can…
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On the Effect of Clutch Dynamic Properties on Noise, Vibration and Harshness Phenomena

Ford Motor Co Ltd-Martin O'Mahony
Ford Motor Company Ltd-Jeronimas Voveris
  • Technical Paper
  • 2020-01-1510
To be published on 2020-06-03 by SAE International in United States
Noise, vibration and harshness phenomena (NVH) can manifest itself during the engagement and disengagement process of dry friction clutch systems. Such phenomena can have a negative impact on cabin occupants driving experience (as well as others in the immediate vicinity of the vehicle). Typically, unwanted NVH phenomena that pertain to the clutch system include Judder, Chatter, Squeal and Eek. These phenomena are recognised by the quality of the radiated noise, as well as the dynamics occurring during clutch actuation. The aim of the current study is to utilise a numerical clutch system model (fully coupling the main motions of clutch components) to predict clutch dynamics during engagement manoeuvres. The model will be used to assess the effect of various clutch design parameters on mitigating system instability. The clutch model utilises measured coefficient of friction data from a rotary tribometer at representative slip speeds and contact pressures. The paper highlights potential NVH issues and demonstrates the improvement of such unwanted behaviour through varying clutch system dynamic properties. The improved understanding of the parameters that affect the…
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Thermal Analysis of Clutch Assembly Using Co-Simulation Approach

Mahindra & Mahindra Ltd-Tanmay Sushant Santra, Nagarajan Gopinathan, Kumar Raju, Ganesh Sugumar, Udaya Paradarami, Vikraman Vellandi
  • Technical Paper
  • 2020-28-0024
To be published on 2020-04-30 by SAE International in United States
Automotive clutches are rotary components which transmits the torque from the engine to the transmission. The flywheel lining rotates with the engine, and the pressure plate is rotating with the transmission input shaft, both parts are rotating at different speeds, dependent on the engine speed and the engaged gear ratio. During the engagement, due the difference in speed of the shafts the friction lining initially slips until it makes a complete engagement. Enormous amount of heat is generated due to the slippage of the friction lining, leading to poor shift quality & clutch failure. Depending on the road & traffic conditions, & frequency of engagement and disengagement of the clutch, it generates transient heating & cooling cycles. The friction coefficient drops sharply until it cannot pass valid torque once temperature exceeds the threshold value. This further worsen clutch slippage and lead to more severe temperature rise. To preform transient CFD simulation, co-simulation methodology is applied, for the clutch to predict operating surface temperature of both pressure, flywheel & air temperature for hill holding with maximum…
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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
This paper considers using linear quadratic regulation (LQR) for multi-input control of the Automatic Transmission (AT) upshift inertia phase. The considered control inputs include the transmission input/engine torque, oncoming clutch torque, and traditionally not used off-going clutch torque. Use of the off-going clutch has been motivated by discussed Control Trajectory Optimization (CTO) results demonstrating that employing the off-going clutch during the inertia phase along with the main, oncoming clutch can improve the upshift control performance in terms of the shift duration and/or comfort by trading off the transmission efficiency and control simplicity to some extent. The proposed LQR approach provides setting an optimal trade-off between the conflicting criteria related to driving comfort and clutches thermal energy loss. It ensures tracking a linear-like profile of oncoming clutch slip speed reference, which was found to be nearly optimal based on control trajectory optimization results. A special attention is given on proper implementation of nonlinear energy loss term through LQR cost function cross term and using a clipped optimal control approach to provide that the clutches (described as…
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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
The present work is focussed on the real-world challenges of a dual mass flywheel (DMF) equipped vehicle in the Indian market. DMFs are widely used to isolate the drivetrain from the high torsional vibrations induced by the engine. While DMFs can significantly improve noise, vibration and harshness (NVH) characteristics of a vehicle, there are multiple challenges experienced in real-world operating conditions when compared with the single mass flywheel (SMF). The present work explains the challenges of using a DMF in a high power-density diesel powertrain for a multi-purpose vehicle (MPV) application in the Indian market. Measurements on the flat-road operating conditions revealed that the DMF vehicle is very sensitive for launch behaviour and requires a higher clutch modulation. Vibration measurements at the driver’s seat confirm that the SMF vehicle could be launched more comfortably at the engine idle speed of 850 RPM. However, the DMF vehicle needs a "launch assist" of an additional 100 RPM to meet the acceptable vibration levels in line with that of the SMF. Further, the gradient launch performance of the…
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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 lead to structural damages of the transmission components. In a dual mass flywheel, total inertia is divided into two parts: a primary mass connected to the engine and a secondary mass to the transmission. The torque delivered by the engine is transferred from one mass to the other through a drive plate and a set of arc springs, the latter absorbing the torsional oscillations coming from internal combustion engine and the shocks caused by fast clutch engagements. This paper investigates overtorque issues and proposes a solution based on a torque limiter, consisting of a friction clutch inserted between the two masses, that limits the maximum torque transmitted through it. The basic idea is to replace the classic flat drive plate with a tapered drive plate that functions as a Belleville spring. The experimental analysis carried out on dedicated benches has tested the elastic characteristic of the tapered drive plate, the durability of friction pads and the variation of the…
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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.