This SAE Recommended Practice is intended as the definition of a standard test, which may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use.The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems.The specific purpose of this document is to define a µPVT Test for the evaluation of the variation of wet friction system performance as a function of speed, temperature, and pressure. This procedure is intended as a standard for both suppliers and end users.The only variables selected by the supplier or user of the friction system are:a. Friction materialb. Fluidc. Reaction platesThese three variables must be clearly identified when reporting the results of this test. If any of the test parameters or system hardware as described in

Automatic Transmission and Transaxle Committee

SAE No. 2 Friction Test Machine 6000 rpm Stepped Power Test

J2488_202511 (Current)

11/25/2025

This SAE Recommended Practice is intended as the definition of a standard test, but may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use.The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems.The specific purpose of this document is to define a 6000 rpm stepped power test for the evaluation of wet friction system performance variation as a function of power level. This procedure uses an initial engagement speed of 6000 rpm and is intended as a standard procedure for common use by both suppliers and end users.The only variables selected by the supplier or user of the friction system are:a. Friction materialb. Fluidc. Reaction platesThese three variables must be clearly identified when reporting the results of using this test

Automatic Transmission and Transaxle Committee

SAE No. 2 Friction Test Machine 3600 rpm Stepped Power Test

J2487_202511 (Current)

11/21/2025

This SAE Recommended Practice is intended as the definition of a standard test, but may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use.The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems.The specific purpose of this document is to define a 3600 rpm Stepped Power Test for the evaluation of wet friction system performance variation as a function of power level. This procedure uses an initial engagement speed of 3600 rpm and is intended as a standard procedure for common use by both suppliers and end users.The only variables selected by the supplier or user of the friction system are:a. Friction Materialb. Fluidc. Reaction PlatesThese three variables must be clearly identified when reporting the results of using this test

Automatic Transmission and Transaxle Committee

The Influence of Torsional Vibrations on the Longevity of Manual Transmission Synchronizers and the Durability of Clutch Dampers

2024-01-501001/25/2024

This study delves into the impact of engine torsional vibration on transmission component failures, specifically synchronizers and clutch damper springs. Synchronizers are crucial in ensuring smooth gear shifts by synchronizing the rotational speeds of the transmission input and output shafts. While design factors such as geometry, friction material, and lubrication are often attributed to synchronizer failures, engine-generated torsional vibrations significantly affect their lifespan. Clutch damper mechanisms integrated into the clutch disc are designed to mitigate these vibrations. This research employs 1D powertrain simulation modeling to predict powertrain torsional vibration behavior. Additionally, rig tests are conducted to simulate vehicle-level angular accelerations and examine the impact of torsional vibrations on synchronizer life. The results provide valuable insights into optimizing clutch damper design to effectively dampen vibrations and prolong transmission component

Jagtap, Amol, Rudramath, Sagar, Chollangi, Damodar, Bhandari, Kiran

Drivetrain pressure spike evaluation methodology & optimization: Simulation and Testing Correlation

2024-26-027701/16/2024

This paper describes a simulation methodology developed for pressure spike evaluation and optimization of hydraulic system architecture for off-highway applications with hydraulically actuated clutch. This pressure spike leads to a very high torque spike in driveline components during clutch pop-up conditions in puddling operations. These torque spikes lead to potential failure of driveline components i.e. gear, shaft, bearing and torsional damper during sudden engagement events. To assess the hydraulic system performance during clutch pop-up cornering conditions is very challenging and leads to compromise on operator safety in the paddy field. It is essential to develop a simulation methodology in a virtual environment to understand the system behavior during clutch pop-up condition and impact of various hydraulic system parameters. This study adopts a model-based design approach for understanding hydraulic system pressure spike phenomenon and dynamic response. Pressure spike

Memane, Nilesh, Kumar, Suneel, Veerkar, Vikrant

Development of Transmission adaptor for diesel engine application

2024-26-033601/16/2024

Transmission adapter is solid, located on cylinder block , on which sits the transmission housing. The function of a flexplate is to provide a mounting point for a torque converter which is used to couple the engine and transmission together when an automatic transmission is used. Transmission adapter provide access for torque convertor and flexplate assembly and protect the flexplate from external environment. Transmission adapter is also support and locate the starter. This study deals with different alloy grade material use, improvement in process to reduce porosity. Porosity observed in first samples of the proposed grade material. The study represents investigation of Transmission adaptor porosity root cause. This also included visual observation, radiography -X ray testing , analysis,3D scan, dimensional inspection, chemical analysis and comparison, tensile testing, truck testing validation tasks. Make sure critical parameter of the clearance meet between flexplate and

Karale, Pranjali

A Study on Reduction of Gear Rattle Noise through Clutch Hysteresis Stabilization

2025-01-010005/05/2023

Reducing gear rattle noise within the passenger cabin is a crucial objective in vehicle development due to its direct impact on customer comfort and driving experience. Gear rattle occurs when free gears collide during meshing, primarily driven by high torsional vibrations generated by engine fluctuations. These vibrations are transmitted through the clutch system to the transmission, amplifying noise inside the cabin. To address this issue, this study focuses on optimizing the clutch by stabilizing its hysteresis, which helps in minimizing the torsional vibrations transferred to the transmission input shaft, thereby reducing gear rattle. The investigation centers on a case where significant gear rattle was observed at high vehicle speeds, particularly under high engine torque conditions. A thorough root cause analysis identified that the primary contributor to the noise was a drop in the clutch hysteresis value at elevated engine torques. This drop increased torsional vibrations in

Awasthi, Mradul, Dhankhar, Dinesh Singh, Khare, Devendra Kumar, Rana, Deepak, pandey, Anant

Impact of torsional vibrations on the strength of clutch dampers.

2025-01-009905/05/2023

The clutch is a mechanical device that engages and disengages power transmission from the engine to the wheels. The damper mechanism integrated into the clutch disc is designed to attenuate the torsional vibrations from the engine. This study investigates the impact of torsional vibrations on the structural durability of a clutch disc damper of the intermediate and light commercial vehicle. The baseline clutch damper's springs experienced excessive deflection angles due to driveline resonance experienced in operation, resulting in the springs hitting the contact surface. This caused the springs to fail due to the high stresses created during operation. A 1D simulation model is utilized to predict the torsional vibration behavior of the vehicle. The driveline's 1D model is created using Amesim software, and the simulated results demonstrate a strong correlation with the actual torsional measurements taken at the vehicle level for the baseline clutch damper. A new clutch damper design

Jagtap, Amol Shivaji, Chollangi, Damodar, PACHPANDE, PRASHANT

Reduction of Lubrication System Pressure Pulsation due to Oil Foaming in a Double Clutch Transmission

2022-28-048711/18/2022

Foaming of Oil is accumulation of air bubbles on the surface. The source of air can be environmental or dissolved air or both. Foaming of Lubricant Oil is an undesired effect which has various reasons to occur- sudden decrease of pressure, contamination, reservoir design, etc. The effects can be pressure pulsation in pump discharge which results in abnormal Noise and Vibration, Cavitation, etc. This paper will describe the mechanical design changes done in a gearbox to guide the Oil flow to a less turbulent passage and to the reservoir. This will allow oil to degas while its flow to the reservoir, largely losing its foamability characteristic. By introducing circular enclosing structure around the rotating Clutch pack, the centrifugally escaping oil is guided and escapes into a collection tray via single point opening. The Oil tray will route the oil back to the reservoir. The enclosing structure around the Clutch pack is a carefully designed two-parts structure with close and

Balasubramani, Prathap, Kaushik, Nikhil

Uncertainty Quantification of Wet Clutch Actuator Behaviors in P2 Hybrid Engine Restart Process

2022-01-079103/29/2022

Advanced features in automotive systems often necessitate the management of complex interactions between system components. To accomplish this task, closed-loop feedback is commonly used for effective real-time controls. Alternatively, open-loop schemes with adaptive parameters can be applied when real-time feedback is infeasible. Although these strategies possess certain levels of robustness, their performance can deteriorate in the presence of significant uncertainties, resulting in undesirable system behaviors. This limitation is often further amplified in systems with complex nonlinear dynamics. A hydro-mechanical clutch actuator is among those systems whose behaviors are highly sensitive to variations in sub-component characteristics and operating environment. In a P2 hybrid system, a wet clutch is utilized for cranking the engine during EV-HEV mode switching. It is critical that a controller is capable of stroking hydro-mechanical clutch actuator as quickly and as consistently as

Yang, Hang, Fujii, Yuji, Zhang, Yijing, Haria, Hiral, Devendran, Ram Sudarsan, Saini, Ankit, Gorodetsky, Alex, Wang, Kon-Well

Optimization of Gaussian Process Regression Model for Characterization of In-Vehicle Wet Clutch Behaviors

2022-01-025303/29/2022

The advancement of Machine-learning (ML) methodology enables a data-driven creation of Reduced Order Model (ROM) for automotive components and systems. In recent years Gaussian Process Regression (GPR) has emerged as a powerful tool for building a static ROM as an alternative to a conventional parametric method. It provides a mathematical framework for probabilistically representing complex non-linear behaviors. Today GPR is available in various programing tools and commercial CAE packages. However, its application requires a careful design consideration such as a selection of input features and a specification of kernel functions, depending on the characteristics of a target system. The GPR design optimization is also driven by application requirements. For example, a moving window size must be tuned to balance performance and computational efficiency for tracking changing system behaviors. In this paper, a detailed design evaluation of GPR is conducted for the characterization of an

Shui, Huanyi, Zhang, Yijing, Yi, Elbert, Bichkar, Akshay, McCallum, James, Upadhyay, Devesh, Miller, Justin, Hopka, Michael, Fujii, Yuji

A Time Efficient Thermal and Hydrodynamic Model for Multi Disc Wet Clutches

2022-01-078603/29/2022

Wet Clutches are used in automotive powertrains to enable compact designs and efficient gear shifting. During the slip phase of engagement, significant flash temperatures arise at the friction disc to separator interface as a result of dissipative frictional losses. An important aspect of the design process is to ensure the interface temperature does not exceed the material temperature threshold at which accelerated wear behaviour and/or thermal degradation occurs. During early stages of a design process, it is advantageous to evaluate numerous system and component design iterations exposed to plethora of possible drive cycles. A simulation tool is needed which can determine what are the critical operating conditions that need to be validated for the system performance and durability to be assured. This paper describes a time-efficient multiphysics model developed to predict clutch disc temperatures with a runtime of minutes. It consists of a simplified 1D numerical model of heat

Morris, Samuel Adam, Morris, Nicholas John, Leighton PhD, Michael

Investigation of the Drag Losses of Wet Clutches at Dip Lubrication

2022-01-078803/29/2022

Wet running multi-plate clutches and brakes are important components of modern automotive and industrial powertrains. In the open stage, drag losses occur due to fluid shearing. This subsequently can lead to a perceptible reduction in the overall drivetrain efficiency. Depending on the application and requirements, injection or dip lubrication is used. For the first one there is already a deep fundamental understanding existing, whereas the latter was not extensively investigated so far. This contribution gives a detailed insight in the experimental research of the drag losses of wet running multi-plate clutches at dip lubrication. In a base study the flow conditions and origins of the drag torque generation were investigated. Built on this, the effects of operating and geometry parameters such as oil viscosity and level, clearance, groove design, disk size and number of gaps on the drag loss characteristic were determined based on a full-factorial testing. The paper further explains

Pointner-Gabriel, Lukas, Forleo, Cosimo, Voelkel, Katharina, Pflaum, Hermann, Stahl, Karsten

Pseudo Transient Torque Converter Clutch Engagement Process Using Fluid-Structure Interaction Simulation

2022-01-078103/29/2022

This investigation utilizes a correlated fluid-structure interaction (FSI) model of the torque converter and clutch assembly to perform a pseudo transient clutch engagement at steady state operating conditions. The pseudo transient condition consists of a series of nine steady state simulations that transition the torque converter clutch from fully released to near full lockup at a constant input torque and output speed representative of a highway cruising speed. The flow and pressured field of the torque converter torus and clutch are solved using a CFD model and then passed along to a transient structural model to determine the torque capacity of the lockup clutch. Bulk property assumptions regarding the friction material, deformation of the clutch plate and deflection of supporting structures were made to simplify the model setup, run time and solution convergence. Telemetry pressure measurements acquired in an operating torque converter under similar operating conditions on a

Beldar, Aniket, Robinette, Darrell, Blough, Jason

Vehicle surge reduction technology during towing in parallel HEV pickup trucks

2022-01-073303/29/2022

In order to ensure the comfort of the parallel HEV pickup truck, this report proposes a vehicle surge reduction technology during towing that utilizes a motor and shifting. Hybridization is one of the approaches to reduce fuel consumption toward the realization of carbon neutrality. The parallel HEV is more advantageous to high-load operation such as towing and loading, which are often used in pickup trucks than the series parallel HEV represented by the Toyota Hybrid System. Since the parallel HEV has an engine, motor, torque converter, and transmission connected in series, a vehicle surge may occur when engaging the lockup clutch due to fuel efficiency and drivability needs, as with conventional powertrains. Vehicle surge is a low-frequency vibration phenomenon. In general, the applied force is the torque fluctuation caused by the engine and tires, and the amplification is the driveline torsional first-order resonance, suspension resonance, and cabin resonance. The vibration is more

Okaya, Shingo, Kokaji, Jun, Quinteros, Luis, Hasegawa, Yoshio, Masunaga, Seiji

Normally Locked Torque Converter as an Alternative Mutli-speed Transmission for Electric Vehicles

2022-01-077503/29/2022

An emerging trend in electric vehicle (EV) propulsion system engineering is the proposal of a wide range of two-speed transmission to improve performance, energy consumption and potentially alter electric motor characteristics. This paper proposes the design and integration of a torque converter and clutch-damper assembly that is normally locked as an alternative means of achieving a two-speed transmission for EV drive units. The layout of the drive unit with the torque converter is included along with an overview of the hydraulic system and control strategy to minimize energy consumption. The performance attributes required to match the torque converter to an electric motor verse an internal combustion engine are reviewed in the context of achieve comparable performance to a two speed transmission tractive effort. Dynamometer testing of a torque converter in both rotational directions is provided to highlight the preferred method of operation during reverse operation of the drive unit

Robinette, Darrell

Innovative Experimental Approach towards Gear Rattle Investigation

2022-01-078403/29/2022

Today’s customers are very thoughtful towards a new vehicle purchase. Along with the vehicle performance, overall vehicle NVH quality is also one of the most important factor which affects their buying decision. During any new product development, gearbox rattle noise is a fundamental NVH problem which requires to be addressed and solved in the early stages. Gear rattle is an annoying noise phenomenon of the automotive transmission, which is mainly induced by torsional fluctuation of engine. This fluctuation is passed from clutch system to the transmission. The torsional vibration causes the free gears inside the transmission to impact each other, which generates so-called the gear rattle noise. The noise source of the gear rattle in the manual transmission is due to the impact of gears oscillating through their gear backlash and the noise will transfer into the vehicle cabin through the transmission case via shafts, bearings and vehicle structures. This paper describes an experimental

Vaishya, Abhishek Lakhanlal

Wheel Torque-based Control: Transmission Input Torque Determination and Inertia Compensation

2022-01-089703/29/2022

Traditionally, production vehicles have interpreted the driver pedal request as a transmission input torque demand. However, with the advent of electrified vehicles, where actuators are located at different positions in the drivetrain, and of autonomous vehicles, which are self-driving, there is a requirement to interpret the demand (either human or virtual) in the vehicle acceleration domain. To address this requirement, we develop a Wheel Torque-based longitudinal Control (WTC) framework, wherein the desired vehicle acceleration is first expressed as a wheel torque demand and then transformed into each actuator’s torque domain. For powertrains with a step-ratio transmission and a torque converter (TC), a key challenge of the WTC framework is the determination of the torque request in the transmission input domain, especially during open or slipping TC operation. This determination needs to take into account the Inertia Compensation Torque (ICT), i.e., the torque required to spin up

Roy, Judhajit, Ravichandran, Maruthi, Meyer, Jason, Zhao, Yanan

Improving the design of automotive air conditioning compressors by predicting the minimum engagement voltage of electromagnetic clutches

2022-01-020603/29/2022

In order to insure passengers comfort, automotive air conditioning compressors are designed to be operational in case of low battery voltage. However, the “minimum engagement voltage” of compressors is mostly driven by designers’ know-how and rely extensively on laboratory tests, which can lead to two issues: Costly design modifications if problems are detected too late in the validation phase and the necessity to perform several design iterations before reaching the desired target. This paper presents the benefit of predicting the minimum engagement voltage where both of these drawbacks can be avoided, leading to a more robust design process. The method was tested on an electromagnetic clutch whose purpose is to engage the compressor when the air conditioning is turned on by passengers. The magnetic field generated by the clutch was estimated using an electromagnetic simulation software. Coil design parameters, materials magnetic properties, clutch assembly geometry and air gaps were

PLUY, Nicolas, Ohk, Changheon

Toyota’s New Hybrid Unit “L4A0”

2022-01-079503/29/2022

Toyota developed a new hybrid unit “L4A0” for the new Tundra, which creates both good drivability and environmental performance. To ensure off-road, towing performance and typically truck driving characteristics, the unit is based on a transmission with a torque converter and multi-plate lock up clutch, and installing a motor and K0 clutch between the engine and transmission. The motor and K0 clutch are built into a module, making it possible to create new hybrid units by combining the module with various transmissions. The unit features many different motor controls. For example, in the case of step-in acceleration input, typically to achieve the desired output torque, a kick-down shift is necessary; however, utilizing “L4A0” both high response and high power output is realized without a kick-down shift. This is accomplished by assisting the engine with the motor during engine torque delay at low engine revolutions. Simultaneously, this contributed to better fuel economy by allowing

Tan, Guodong, Ikemura, Masashi, Hasegawa, Yoshio, Ohki, Takao, Baba, Masayuki, Nakamura, Atsuro, Herring, Craig, Niinomi, Atsushi, Hamano, Makoto, Mizoguchi, Yasuhiro

Adaptive control strategy for complex starting conditions of vehicles with dry dual clutch transmission

2022-01-033003/29/2022

For vehicles equipped with the dry dual clutch transmission, due to the diversity of starting conditions, it is a nontrivial task for control strategy to meet the requirements of all kinds of complex starting conditions, which is easy to cause large starting shock and serious clutch wear. Therefore, it is proposed in this paper an adaptive control strategy for complex starting conditions by adjusting two clutches to participate in the starting process at the same time. Based on establishing the transmission system model and clutch model, the starting conditions are identified in terms of starting speed, road adhesion, and driver's intention, in which the driver's intention is identified by fuzzy reasoning model. Based on the identification of starting conditions and considering the safety principle, it is selected the appropriate starting gear and clutch combination mode, and adjusted the combination speed of the two clutches to carry out an adaptive control strategy. The Simulink

Guo, Jun, Wu, Jinglai, Zhang, Yunqing

Simulation of Dynamic and Thermal stresses on clutch assembly and Study of their effect on clutch pedal effort characteristics

2022-01-031103/29/2022

Single plate dry clutch has to sustain higher thermal stresses combined with different dynamic operating conditions during vehicle usage. With growing population of traffic in cities, temperature sustainability of clutch is affected which is evident from the rise in complaints on clutch from metropolitan cities. Child parts of the clutch cover assembly such as diaphragm spring, straps, etc. should be able to sustain the higher operating temperature without much deterioration in the assembly functional parameters such as release load, clamp load, pressure plate lift. Further, different operating speeds of the engine induces different dynamic stresses in the clutch components, adding into the thermal effect. The effect of critical performance attributes of clutch system is on clutch pedal effort characteristics. The deterioration in the release load of the clutch directly affects the clutch pedal effort characteristics and clutch pedal feel for the driver. The clutch release system

Katarki, Shrirang Sharad, Mohire, Sujit, Tendulkar, Vishveshvar, Deokar, Kiran, Sontakke, Swapnil

Thermomechanical Instabilities in Metal-Free Friction Materials Using a Nonlinear Transient Simulation Approach

2021-01-128610/11/2021

The invention of metal-free friction materials is gaining popularity in the manufacturing of brake pads and clutch friction discs because of the negative factors associated with metals such as copper. To gain more insight into the failure mechanism of the recent invention during brake or clutch applications, a nonlinear transient thermomechanical model is established using Finite Element Code. The model is based on a two-dimensional configuration for an investigation on the onset of TMI (Thermo-Mechanical Instability) during sliding contact in such material. The model is validated by comparing the transient simulation results for a full-contact regime to the result from the existing eigenvalue method. A parametric study is carried out to examine how the thermal conductivities and the elastic moduli influence TMI. The simulation results show that the thermal conductivities in the transverse direction and elastic moduli in the longitudinal direction can stabilize the system. Conversely

Koranteng, Kingsford, Shaahu, Joseph-shaahu, Yi, Yun-Bo

Dynamic Brake Test Stand

2021-01-127410/11/2021

Nowadays, inertia dynamometers or roller dynamometers are used for the development and testing of vehicle brakes. However, these testing methods are either entirely unable to simulate dynamical conditions, close to real driving maneuvers, or they can do so approximately only at very high costs. This means that brakes, braking systems and brake-related assistance systems such as the ESC system can ultimately only be tested in a full prototype of the car, or before that on hardware-in-the-loop test stands. In the case of the ESC, these test stands have to simulate the behavior of the brake and the surrounding vehicle in real time, then stimulate the interfaces of the ESC sensors accordingly, and finally evaluate the reaction of the ESC system in different situations. The problem here, however, is that the braking system can only be approximated by simulations. Nevertheless, it would be important to be able to carry out detailed stability tests with real hardware on suitable brake test

Kraus, Andreas, Stiegelmeyr, Andreas

Optimum Solution for Reduction of Clutch Pedal Vibration and Groan Noise Observed During Clutch Pedal Actuation

2021-28-016910/01/2021

Abstract In emerging markets like India, manual transmission vehicles are still most preferred & contributes to 85% of passenger vehicle sales due to its cost benefit. However, customer expects good NVH behavior for comfortable driving experience in the vehicle to maneuver effortlessly in the highly congested traffic conditions in India. Clutch & its hydraulic release system in manual transmission of IC engines are the significant components which affects the NVH behavior & maneuverability of the vehicle and the driver comfort significantly. This paper focuses on the clutch pedal vibration & groan noise concern observed during clutch pedal actuation in high power density SUV vehicle developed for Indian market. The vehicle had highly efficient & light weight engine which has high engine axial vibrations. Axial vibrations are caused due to engine firing impulses & crankshaft bending causes flywheel axial movement. This movement in turn leads to vibrations in clutch cover diaphragm

VARUN KUMAR, D, Sathish, PB, Vellandi, Vikraman, M, Sudhan, Vijayarangan, Deepak

A Unique Methodology to Improve the Clutch Pedal Characteristics of a Compact Sports Utility vehicle

2021-28-024310/01/2021

Clutch characteristics play a vital role in ensuring a smooth and comfortable customer experience of any vehicle. The expectation is to have an optimized clutch pedal effort, reduced pedal travel, adequate modulation zone and a smooth and quick pedal returnability. However, achieving all these customer requirements is extremely challenging in some cases. In the present work, the authors discuss on improving the clutch pedal characteristics of a compact sports utility vehicle (SUV by adapting a unique approach of combining a dual torsion spring (DTS) and a return spring (RS). DTS is widely used in the clutch pedal to improve the pre-load at zero travel (1.5 kg to 2.0 kg) to improve the pedal returnability in the free-play zone. Moreover, it is also quite helpful to reduce the peak pedal effort by giving a positive assistance. However, the introduction of DTS would also bring down the pedal effort (pedal holding force) at the end of the travel affecting the pedal returnability at the

Vellandi, Vikraman, Kanagaraj, Pothiraj

Optimization of Clutch pedal Vibration with hydraulic damper & influence on its position in resolving the vibration without compromising Efficiency of the system

2021-28-024710/01/2021

The clutch pedal in manual transmission plays a significant role in defining the comfort of driver as the component is one of the customer's touchpoint in the vehicle. Whenever driver operates the clutch pedal, comfort & NVH refinement should be felt over the complete pedal travel. The expectations of customer on NVH refinements, such as pedal vibration felt on foot during actuation, becomes the part of perceived Quality and hence addressing the concern is very crucial. Due to advancements of technology & down-sizing of engines, NVH becomes the challenging area where the clutch pedal vibrations need to be eliminated to improve the comfort. In this paper we are explaining the problem statement & NVH solution to eliminate the clutch pedal vibration observed during clutch pedal actuation. Pedal vibrations were very severe at 10% clutch pedal pressed condition, and the same tends to diminish till 50% clutch pedal pressed condition. From initial position (0% clutch pedal pressed condition

S, Kesavprasad, Vellandi, Vikraman, M, Sudhan, Vijayarangan, Deepak

Assessing the effect of torque converter losses on the start emission and Engine stability in TGDI AT Vehicle

2021-28-018510/01/2021

The emission norms around the world are continuously changing and getting stringent with every revision. India is on its way to make its emission norms at par with that prevailing in the developed nations. The cold-start condition is an important factor affecting vehicle emissions from gasoline direct injection (GDI) and port fuel injection (PFI) engines. In this paper, the effects of change in torque converter losses on emissions are experimentally investigated in a TGDI AT vehicle. The instant engagement of the torque converter puts a sudden torque on the engine and thus affects its stability. Thus, to overcome the stability issue, Engine torque has to be simultaneously increased for smooth engagement. As a result, the likelihood of the slightly leaner air-fuel mixture in the cylinder, which results in higher Nox formation, is much greater in an AT vehicle than that of a similar MT vehicle. Additionally, the temporary ineffectiveness of motor vehicle emission controls at startup

RAI, ABHISHEK, SARAN KUMAR REDDY, KETHIREDDY, SOMANI, KAPIL

A Unique Methodology to Evaluate the Metallic noise concern of a Dual-Mass Flywheel Under Real-World Usage Conditions

2021-28-024910/01/2021

Dual mass flywheel (DMF) is an excellent solution to improve the noise, vibration and harshness (NVH) characteristic of any vehicle by isolating the driveline from the engine torsional vibrations. For the same reason, DMFs are widely used in high power-density diesel and gasoline engines. However, the real-world usage conditions pose a lot of challenges to the robustness of the DMF. In the present work, a new methodology is developed to evaluate the robustness of a DMF capturing the RWUP conditions fitted in a Sports utility vehicle (SUV) with front-wheel drive architecture. During engagement of clutch system, enormous amount of energy is dissipated. To sustain the operating temperature of the clutch system, generated energy is dissipated through conduction & convection. If the temperature of the clutch friction material is not retained, clutch burning & burst failures happens. Ventilation holes are provided on clutch housing to improve convective heat transfer. During rainy season in

S, Kesavprasad, M, Sudhan, Vijayarangan, Deepak, Rai, Vikas

An experimental approach to monitor the clutch thermal condition to increase the clutch life

2021-28-028110/01/2021

One of the top problems that every Indian automobile manufacturer struggles to manage is the clutch early failure less than 30000 Km. This is mainly due to the extreme heating of the friction lining due to the real-world user profile in the Indian market and users inappropriate driving behaviors like Overloading the goods more than the manufacturer’s recommendation, Non recommended attachments and increased wheel size, Thick traffic leading to high level of clutch modulation and Clutch riding while running and launching the vehicle at higher gears. Although many simulation and testing are done during the development phase, above listed real world user profile and customer driving habits are inevitable by any automobile manufacturer. Hence the prime goal of this experimental research is to indicate or alert the user on the clutch thermal condition due to the driving habit and to encourage the user on right driving habits. This objective is met through an stand alone electronic system

M, Sudhan, B, Vasanthan

Necessity of damper for Hydrostatic Transmission (HST) Tractors

2021-26-027809/22/2021

In a modern world, the tractor customer demands are increasing for more comfortable, new technology, fuel efficient and quieter vehicle. The customer’s expectation for NVH refinement often challenges the limitations for tractor designs. For smaller tractors Hydrostatic Transmission (HST) is need due to higher demand for fuel efficiency, lightweight powertrain, and the operation will become easy in the field. With the Hydrostatic Transmission (HST) tractor without damper, there is a technical challenge like withstanding of the sudden impacts from the implements which are connected to PTO during field operations. The NVH behavior in driveline is critical phenomena which can cause the discomfort to end users and structural failure of driveline parts. During gear engagement due to sudden variation in torque the driveline parts are tends to clash each other because of lashes which will create high level of angular acceleration and noise. Practical measurement study has been done to identify

Rajendran, Ashok Kumar, Bagadekar, Vijaykumar, Alavilli, Satya Pavan

Analytical methodology For the Prediction Of The Wear Of Damper Springs In Dry Friction Clutches

2021-26-038409/22/2021

Coil springs are crucial components of the clutch damper. Quantifying the stresses accumulated on them during operation is crucial in the prediction of remaining usable spring life. This paper demonstrates the use of a mathematical model based approach in predicting the behavior of localized stresses on the spring used in clutch dampers. An equivalent cantilever beam model for spring coils solved using the theory of elastic stability is utilized to predict the spring response in operation, a contact model that translates the spring response into localized stresses due to wear and iterative wear model that accounts for surface morphology and change in geometry due to wear is illustrated in this paper for the prediction of wear.

Anna Jothikumar, Saravana Kumar, Datta, Sauradeep, McCutcheon, Steve, Venkataraman, Aarkesh

Bus NVH refinement: A Journey towards Comfortable Future

2021-26-027209/22/2021

The future of bus transit in new millennium is promising. This optimism is based on an anticipated long-term slowdown in growth of suburbs and revitalization of central cities. It reflects and escalates the public concern with traffic congestion, sprawl and pollution. This calls for double the use of public transport to address above issues. It calls for changing the mind-set of society towards public transports like buses, coaches etc. This could happen if bus design ensures right comfort, safety & TCO by ensuring refined bus transport. Hence, it is responsibility of OEMs to provide the new generation buses and coaches, which will ensure the public demands of comforts in terms of NVH refinement. This paper covers the innovative approach used to convert the existing bus NVH refinement to next level as a short-term solution and with the intention of articulating NVH strategies for new generation bus development. This work explains combined experimental and simulation approach deployed

Doshi, Sohin, Taware, Girish, Kalsule, Dhanaji, Bijwe, Vilas, Naidu, Sudhakara

Slip energy evaluation for a conventional friction clutch

2021-26-048009/22/2021

The importance of clutch in a vehicle’s performance is not new to the automotive, commercial or agricultural sectors. So is the importance of the clutch life when it comes to the durability of a vehicle. In process of making the machines more and more efficient, one can observe a steady reduction in the overall mass of the vehicle and the parts in it. While the parts were heavier, and the friction lining surfaces were more than adequate, the life of clutch has been the best. But with reduction of the overall masses, the energy has lesser amount of sink to dissipate and is being liberated in the form of heat, rising the overall temperatures. This leads to an early wear or even a burn in the clutch. In such scenario, it is necessary to estimate accurately the energy dissipation through a defined cycle to understand the clutch performance. Although different methods exist to evaluate energy, most cases include obtaining a high amount of sophisticated data. This paper discusses a simpler

Alavilli, Satya Pavan, KADHAR MAIDEEN, SALIM MALIK

Improving the clutch design robustness by Virtual validation to Predict Clutch Energy Dissipation and Temperature in Clutch Housing

2021-26-032909/22/2021

Clutch is a very important component of any vehicle equipped with the manual transmission (MT), automated manual transmission (AMT) or dual-clutch transmission (DCT). During launch of a vehicle(moving from “0” speed), clutch is being slowly engaged by the Driver or TCU(for AMT vehicle) for smooth torque transfer between engine and transmission. The clutch is design to transfer max engine torque with min heat generation. During the clutch engagement, the difference in the input (engine flywheel) and output shaft (clutch disc) speed of clutch called the clutch slipping phase which then leads to a huge amount of energy being dissipated in terms heat due to friction. As a result, clutch surface temperature increase consistently, when the surface temperature cross the threshold limit, the clutch wear out quickly or burns spontaneously. Hence it is crucial to predict the energy dissipation and temperature variation in various components of clutch assembly through virtual simulation. During

Ganesh, Mohan Selvakumar, Chopra, Ujjwal, Kanagaraj, Pothiraj, M, Sudhan

Co-Simulation of BLDC Motor Control and Clutch actuation system with Ball Ramp Mechanism

2021-01-123609/21/2021

Electro-mechanical actuators are widely used in different forms in the automotive industry these days and are very effective in translating rotary motion of the motor to a linear motion with precision as per the requirement. With onset of electric drivelines and other complex driveline configurations, we see an increase in actuator applications. In this study, we developed high fidelity analytical model for a ball ramp clutch actuation system as per the proposed mechanical design and the software controls. The controls architecture is built in SIMULINK environment to drive the plant model of the BLDC motor. Whereas, the entire mechanical system which includes the gear train, ball ramp mechanism, clutch pack stiffness, etc. is modelled in ADAMS tool. The Ball Ramp consists of metal balls positioned in between opposing paired arc-shaped ramp grooves and guided by a cage to keep them equally separated in the same plane. While ADAMS model deals with high-fidelity contact dynamics using non

Rajendran, Raveen K., Roy, Nantu, Mehta, Yogesh

Customized and market specific thermal robust clutch system solution

2021-01-123909/21/2021

The goal of reducing fuel consumption and CO2-Emission is leading to turbo-charged combustion engines that deliver high torque at low speeds (down speeding). To meet NVH requirements damper technologies such as DMF (Dual Mass Flywheel) are established, leading to reduced space for the clutch system. Specific measures need to be considered if switching over from SMF (Single Mass Flywheel) to DMF. It has an impact on thermal behavior of the clutch system for example due to reduced and different distribution of thermal masses and heat transfer to surroundings. Taking these trends into account, clutch systems within vehicle power-trains are facing challenges to meet requirements e.g. clutch life, cost targets and space limitation. Clutch development process must ensure to deliver a clutch system that meets requirements taking boundary conditions such as load cycles and driver behavior into account. Relevant load cycles are derived based on feedback & an analysis of driver behavior under

Kapse, Ravi Ramesh, Lakshminarayanan, Saravanan, Németh, Ákos, Thakare, Ankit, Bernhardt, Johannes

Analyses of Low-Frequency Motorcycle Noise Under Both Steady-State and Transient Operating Conditions

2021-01-110808/31/2021

This paper presents experimental investigations of diagnosing and analyzing the low-frequency, low- SNR (Signal to Noise Ratio) noise sources of three motorcycles using a hybrid technology that consists of a passive SODAR (Sonic Detection And Ranging) and modified HELS (Helmholtz Equation Least Squares) methods. The former enables one to determine the precise locations of multiple sound sources in 3D space simultaneously over the entire frequency range that is consistent with a measurement microphone in non-ideal environment, where there are random background noise and unknown interfering signals. The latter enables one to reconstruct all acoustic quantities such as the acoustic pressure, acoustic intensity, time-averaged acoustic power, radiation patterns, and sound transmission paths through arbitrarily shaped vibrating structures. By combining a passive SODAR and modified HELS methods, engineers are able to reveal the low-frequency noise sources that cannot be accomplished by using

Lu, Yazhong, Wu, Sean, Yuan, Zeyu, He, Wen, li, Zhaoting, Li, Huijun

Driveline Torsional Vibration Analysis and Clutch Damper Characteristics Optimization for reducing Commercial Vehicle Noise and Vibrations

2021-01-110208/31/2021

The automotive world has seen an increase in customer demands for vehicles having low noise and vibrations. One of the most important source of noise and vibrations associated with vehicles is the vibration of driveline systems. For commercial vehicles, the refinement of drivelines from NVH point of view is complex due to the cost and efficiency constraints. The typical rear wheel drive configuration of commercial vehicles mostly amplifies the torsional vibrations produced by engine which results into higher noise in the vehicle operating speed range. Theoretically, there are various options available for fine tuning the torsional vibration performance of the vehicle drive train. The mass moments of inertia and stiffness of the drivetrain components play significant role in torsional vibration damping, however, except minor changes to flywheel mass, it is hardly possible to change other components, subject to design limitations. Considering this, clutch disc torque twist

Jagtap, Amol, Chollangi, Damodar, Mamoriya, Sandeep

Vibration Mitigation of Dynamic Skip Fire Engines with Flywheel Optimization and Torque Converter Clutch Slip

2021-01-110508/31/2021

Dynamic Skip Fire (DSF) is an advanced cylinder deactivation technology to reduce fuel consumption and emissions of internal combustion engines. The firing sequence may vary dynamically depending on driver demanded torque with all cylinders capable of deactivation. This creates a challenge for managing noise vibration and harshness (NVH) caused by the low frequency excitation in the engine’s torque profile, especially in smaller engines with 3 or 4 cylinders. Due to the varying nature of firing sequences, the excitation is not limited to one or two engine orders and can vary with time, requiring broadband mitigation of the driveline. This work proposes the optimization of flywheel inertia combined with careful control of torque converter slip to overcome this challenge. Four different flywheel configurations and varying levels of torque converter slip were tested on a VW Jetta fitted with a 1.8L 4-cylinder engine with DSF control capability. For each configuration, DSF flyzone maps

Srinivasan, Vijay, Arvanitis, Anastasios

Modeling and Simulation of Clutch Damper Spring Saturation Phenomenon

2021-01-110408/31/2021

In modern automotive vehicles, there is a major concern for noise and vibrations generating from drivetrain. These noise and vibrations affect the passenger comfort and drivetrain parts life. Engine generates fluctuating torque and causes angular acceleration that results into torsional vibrations. These vibrations are transmitted to powertrain. Clutch disc consists damper springs and hysteresis which aids reducing these torsional vibrations. Based on the damper spring stiffness, one can control the resonance speed range and shift the resonance rpm out of driving speed range of engine. The resonance should not happen within driving speed range of vehicle to avoid large amplitude torsional vibration. But here limitation is put on the torque transmission capability of clutch for meeting vehicle requirements. As, low stiffness of damper spring requires large wind-up angle so, it is critical to decide its stiffness. The present work is related to resolving the issues of clutch damper

Mamoriya, Sandeep, Chollangi, Damodar, Jagtap, Amol

Innovative Control and Monitoring Algorithms and Strategies Based on Judicious Functional Partitioning and Frugal Engineering Concepts

2021-01-0124

04/06/2021

As embedded electronic control systems are increasingly penetrating vehicle subsystems, the designers are faced with a dilemma of providing state of art vehicle features on one hand and ensuring frugal implementation of the same to meet competitive pressures on the other. For embedded software and hardware systems this means adoption of judicious and innovative design choices with reusable building blocks. This paper dwells upon various design aspects of control and monitoring which are frequently used for automotive applications such as feed-forward and proportional integral control, diagnostics for sensor boundary conditions, handling of intermittent faults without causing nuisance to the vehicle users etc.

Vaidya, Vishwas Manohar

Study of Flywheel Energy Storage in a Pure EV Powertrain in a Parallel Hybrid Setup and Development of a Novel Flywheel Design for Regeneration Efficiency Improvement

2021-01-072104/06/2021

In electric vehicles, there is a continuous shift in the charging and discharging of the battery due to energy generation and regeneration. This adds up to the total number of charging-discharging cycles of the battery. This fluctuation amounts to faster battery degradation and life-cycle reduction. Also, we are exploring solutions to improve the low regeneration efficiency of EVs. For example, overall regeneration efficiency from wheels-to-wheels is only around 64% in Tesla Roadster. Even in current EV powertrains, the regeneration efficiency only reaches up to around 75%, which is much lower compared to the potential efficiency of flywheel-based energy storage (FES) as no energy conversion takes place from one form to another. We implemented FESS in a parallel hybrid setup solely for regenerative braking. Based on the power requirements from the vehicle, the drivetrain smartly switches its power source between the Electric motor and flywheel during the drive cycle. It uses a high

Seshadri Venkatesh, Pawan, Chandran, Vishnu, Anil, Sreeram

Effect of Wear on Frictionally Excited Thermoelastic Instability

2020-01-162910/05/2020

The effect of wear on Thermoelastic Instability (TEI) is investigated using a finite element approach. The equations of thermoelasticity, the classical wear law and the conforming contact conditions are considered. The method is based on a two-dimensional, frictional sliding model with a bimaterial interface and a simplified geometry of finite thickness. An assumption of the solution in the perturbation form leads to a quadratic eigenvalue problem. The existing analytical solutions using two infinite half planes are employed to validate the numerical solutions for several representative scenarios, including a limiting case in the absence of wear. The analytical solutions are also sought for the special cases when one of the materials is a non-conductor and when the two materials are identical, for the purpose of comparison. In general, the satisfactory agreements between the numerical and analytical approaches have been obtained. However, there are noticeable discrepancies when the

Qiao, Yijun, Yi, Yun-Bo

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