Browse Topic: Clutch components

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Engine Flywheel Housing and Mating Transmission Housing FlangesJ617_202009 (Current)9/29/2020
This SAE Standard specifies the major dimensions and tolerances for Engine Flywheel Housings and the Mating Transmission Housing Flanges. It also locates the crankshaft flange face or the transmission pilot bore (or pilot bearing bore) stop face in relation to housing SAE flange face. This document is not intended to cover the design of the flywheel housing face mating with the engine crankcase rear face or the design of housing walls and ribs. Housing strength analysis and the selection of housing materials are also excluded. This document applies to any internal combustion engine which can utilize SAE No. 6 through SAE No. 00 size flywheel housing for mounting a transmission.
Automatic Transmission and Transaxle Committee
Development of GM Allison 10-Speed Heavy Duty Transmission2020-01-04384/14/2020
This paper describes the development of the GM Allison 10-Speed Heavy Duty (HD) Transmission. The trend of increased towing capacity and engine horsepower in the automotive heavy-duty truck segment has been steadily climbing for the past 10 years. The development of 10-Speed HD Transmission is designed to be best in class in for towing performance in the 2500/3500 series segment while optimizing fuel economy. The 10-Speed HD Transmission also gives the customers the option to order an integrated power take-off (PTO) unit that benefits downstream installation of utility accessories such as hydraulic pumps, generators, etc.
Lee, Chi Teck, Ames, David, Caldwell, Brett, Knoth, Matthew, Reinhart, Timothy, Kelly, Jeffrey, Kannan, Rajesh, Tanasi, German
A Study of Mechanism of Engine Idling Rattle Noise in Hybrid Transaxles2020-01-04214/14/2020
Quietness is one of the most important characteristics for Hybrid Electric Vehicle quality. Reduction of the rattle noise caused by the torque fluctuation of an internal combustion engine can contribute to get a customer satisfaction. Toyota Hybrid System(THS) also has same requirement. Especially, the rattle noise during idling may happen discontinuously despite of periodical engine combustion excitation. It is necessary to study the mechanism and reduce the rattle noise. At lower engine torque range, decreasing the torsional damper’s stiffness can improve this condition as the manual transaxle done. However, the rattle noise can occur easily in conditions of relatively large torque spike inputs to the torsional system, such as the engine start/stop function of THS using the motor/generator in the transaxle. It is necessary to analyze the dynamics of all related components in lower engine torque range and need to find the new technique satisfying in both the idling and engine start/stop condition. This paper presents one method to clarify the mechanism of rattle noise occurring during engine idling through the measurement of shafts torque, gear speed and gear mesh backlash within a transaxle. The results of the study contributed to the reduction of transaxle rattle noise, positively affecting customer satisfaction.
Takeuchi, Tomoya, Miyasaka, Kenji, Ito, Masatoshi, Nakamura, Shingo
Development of a Component Level Test Methodology to Validate the Transmission Bush of a Manual Gear Box2020-01-14094/14/2020
In the era of fierce competition, launching a defect free product on time would be the key to success. In a modern automobile, the transmission system is designed with utmost care in order to transfer the maximum power from engine to driveline smoothly and efficiently. Optimized design of all the transmission components is necessary in order to meet the power requirement with the least possible weight. This optimization may require gear designs with different internal diameters. The assembly of these gears may not be possible on a solid transmission shaft. To facilitate assembling while retaining optimum design of transmission parts, a separate bush is designed to overcome this limitation. Some bushes may require a flange to restrict any free play of the mounted gear in its axial direction. During complete system level testing of one newly developed manual transmission, bush failure was observed. Bushes are generally press fitted on the transmission shafts, on which the needle roller bearing is mounted. In some cases, the free axial movement of the gear is restricted by the hub or shaft itself. But in other cases, due to assembly constraints, the bush itself is flanged to restrict the axial free play of the gear. When the respective gear is not in engaged condition, the bush does not get any axial thrust. Once the gear is engaged, due to the axial thrust caused by the helical gear, the bush experiences a certain amount of axial thrust. This axial thrust was suspected to be the reason of failure. A component level test set up maintaining the boundary condition was made and axial load was applied on the bush using a hydraulic actuator. The failure mode was simulated consistently, and design modifications were carried out. Modified designs were also tested using the newly derived test methodology and the modified design with the required durability life was adopted for implementation. The complete system level durability test was again performed with the modified bush and no failure was reported thereafter. The component level test methodology helped to test a number of design iterations and a number of samples within a stipulated time and cost. This methodology can be used in all future projects as a part of front-loading support before performing complete system level test.
Kathrecha, Devanshu, Chakraborty, Abhirup, Sirur, Avinash, Sebastian, Jobin, Savla, Jinesh
Characterization and Modeling of Wet Clutch Actuator for High-Fidelity Propulsion System Simulations2020-01-14144/14/2020
Innovations in mobility are built upon a management of complex interactions between sub-systems and components. A need for CAE tools that are capable of system simulations is well recognized, as evidenced by a growing number of commercial packages. However impressive they are, the predictability of such simulations still rests on the representation of the base components. Among them, a wet clutch actuator continues to play a critical role in the next generation propulsion systems. It converts hydraulic pressure to mechanical force to control torque transmitted through a clutch pack. The actuator is typically modeled as a hydraulic piston opposed by a mechanical spring. Because the piston slides over a seal, some models have a framework to account for seal friction. However, there are few contributions to the literature that describe the effects of seals on clutch actuator behaviors. In a routine simulation, a spring constant is commonly tuned to match vehicle data, assuming that it captures the effects of seal friction. The validity of this approach is not well established. This article describes the characterization and empirical modeling of a wet clutch actuator. The effect of seal friction is examined in detail during stroking and de-stroking. It is found that the seal friction is highly non-linear and directional. It introduces a significant error in clutch applied force calculation unless seal friction is explicitly accounted for. Propulsion system simulations are conducted to demonstrate the significant impact of seal friction on clutch operation and the quality of simulations. A framework of a new actuator model is proposed to represent seal friction based on empirical observations of its complex behaviors.
Haria, Hiral, McCallum, James, Fujii, Yuji, Tsuchiya, Takahiro, Miyagawa, Masatoshi, Nakamura, Shinji, Wendel, Matthew, Katopodes, Nikolaos
Active and Passive Control of Torsional Vibration in Vehicle Hybrid Powertrain System2020-01-04084/14/2020
The vibration characteristics of hybrid vehicles are very different from that of traditional fuel vehicles. In this paper, the active and passive control schemes are used to inhibit the vibration issues in vehicle hybrid powertrain system. Firstly the torsional vibration mechanical model including engine, motor and planetary gear subsystems is established. Then the transient vibration responses of typical working condition are analyzed through power control strategy. Consequently the active and passive control of torsional vibration in hybrid powertrain system is proposed. The active control of the motor and generator torque is designed and the vehicle longitudinal vibration is reduced. The vibration of the planetary gear system is ameliorated with passive control method by adding torsional vibration absorbers to power units. The vibration characteristics in vehicle hybrid powertrain system are effectively improved through the active and passive control.
Zhang, Lijun, Zhang, Shijuan, Meng, Dejian, Xu, Jie
A Comprehensive Study on the Challenges of Dual Mass Flywheel in Real-World Operating Conditions of the Indian Market2020-01-10144/14/2020
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 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 up to 12% gradient whereas the SMF variant could negotiate up to 18% gradient easily. Furthermore, the higher launch energy requirement of the DMF is also responsible for the higher temperature of the clutch system by 33% as confirmed by the temperature measurements inside the clutch housing. The increased temperatures pose a major threat to the robustness and useful life of the clutch system parts. Subjective evaluations reveal that the DMF vehicle is prone to frequent engine stalling in speed-breaker and pot-hole manoeuvres. This is mainly due to the requirement of a fuel cut-off strategy which is usually implemented to avoid DMF spring resonance at low engine speeds. However, the requirement of fuel cut-off strategy is not required for the SMF vehicle and hence it could negotiate varying road conditions without any stalling concern. The present work gives a holistic insight into the mentioned challenges with the detailed objective and subjective evaluation data.
Vellandi, Vikraman, Somarajan, Suresh Kumar, Ganesh, Mohan Selvakumar
Optimum Design of an Assist Mechanism for a Motorcycle Multi-Plate Clutch2019-32-05231/24/2020
In recent years, the popularity of leisure-motivated large motorcycles has increased as the demand for high-added value motorcycles is growing. Therefore, large motorcycle engines have become more powerful. Due to this trend, the capacity of the clutch is also required to increase. Contrary to the demand for high engine power and high clutch capacity, reductions in weight, space, operational load, and shock at deceleration are permanent issues of motorcycle development. The consideration of all these issues are required during development of a clutch for large motorcycles. Considering the above issues, a clutch with an assist cam and slipper cam mechanism is effective for cost and performance. The assist cam mechanism allows the clutch to have a larger transmittable torque without an increase of the clutch lever load. The slipper cam mechanism can automatically reduce the transmitted torque when shock from sudden engine braking happens during downshifting. Therefore, the installation of the clutch with cam mechanism on large motorcycles is becoming standard in the motorcycle industry. Regarding smaller motorcycles, the reduction of the number of clutch discs can be realized by adopting an assist mechanism, which enables reductions in weight, space, and the operational amount of the clutch lever. On the other hand, the riding experience while operating a clutch with assist mechanism is considered to be unfavorable compared with a conventional non-assist clutch mechanism; a phenomenon which is anticipated to occur based on the assist mechanism structure and confirmed with our evaluations. This paper focuses on the clutch assist mechanism, specifically the development of the basic theory of a cam to make it applicable for a motorcycle assist clutch and prove the validity of the theoretical formula with test results. The results clarified an efficient setting range of the cam shape of the assist mechanism for the clutch. Furthermore, the practical range of the cam shape was determined to ensure proper operator comfort. From this research, we achieved the optimum design of the assist clutch, which enables comparable riding experience to the conventional non-assist clutch but with all the benefits that the assist mechanism brings.
Minoha, Misaki, Yoneyama, Koji, Imai, Ryoichi, Kitazawa, Hidenori, Mano, Osamu, Miyagawa, Shinya
Optimized Wet Clutch Design2019-32-05531/24/2020
Multi-plate wet clutches used in motorbikes transmit the torque by friction under pressure between driving and driven Plates. The life & performance of the clutch for the friction material used, depends on amount of energy generated during clutch slip, amount & uniformity of heat dissipation amongst the plates and surface texture of mating surfaces. Above parameters if not properly considered during design stage may lead to higher temperature of rubbing surfaces. Higher temperature further reduces the friction coefficient and increases the wear rate of friction material leading ultimately to lower torque capacity of clutch. The temperature rise in a wet clutch is the balance between amount of heat generated and the amount of heat dissipated by oil flowing through clutch. The maximum amount of oil is limited by the requirement of clutch drag torque, Which decides the quality of neutral finding and gear shift feel on vehicle. Further, if roughness of rubbing surfaces is not controlled in mass production, it leads to fast wear of friction material during initial operating cycles. The rate of wear is faster if the heights of surface asperities are of high magnitude. This paper explains the design features of clutch developed by Endurance Technologies Ltd., optimized to achieve above aspects, for the engines having clutch cooling oil supply through the gear box input shaft. I. An innovative oil management concept is incorporated which distributes the oil as per requirement amongst the plates. Adequate distribution of oil facilitates to have optimum oil flow with minimum desired drag torque. It also ensures effective heat dissipation throughout the clutch assembly. A part of oil is directed to cool the clutch clamping springs which reduces the clamping load loss. II. The validation procedure to confirm the adequacy of oil flow through the plurality of plates is developed. III. The defined controlled surface texture of steel plates provides consistent and controlled wear rate in mass production. Further, it ensures the dynamic torque capacity within a narrow band over the longer life span. The above two features of multi-plate wet clutch design achieved reduction in wear by 56 % and improved dynamic torque capacity by 16 % at the end of durability tests.
Bhone, Nitin, Thakare, Sachin, Jahagirdar, Ashutosh
Advanced Bench Test Methodology for Generating Wet Clutch Torque Transfer Functions for Enhanced Drivability Simulations2019-01-234012/19/2019
A wet clutch continues to play a critical role for step-ratio automatic transmissions and finds new utilities in hybrid and electrified propulsion systems. A torque transfer function is often employed in practice for sophisticated clutch slip controls. It provides a simple, yet practical framework to represent clutch torque as a function of actuator force. An accurate transfer function is also increasingly desired in today's vehicle design process to enable upfront assessment of clutch controls through simulations. The most common approach is based on Coulomb's linear friction model, where the coefficients are adaptively identified based on vehicle data. However, it is generally difficult to tune Coulomb's model for hydrodynamic behaviors even if the reference vehicle data are available. It also remains a challenge to produce in-vehicle clutch behaviors on a component test bench to determine realistic transfer function before prototype vehicles are built. SAE#2 test procedure is the industry standard for evaluating clutch frictional behaviors. It is a viable tool for durability assessment, but not designed to characterize hydrodynamic behaviors for clutch controls. This research focuses on the development of a methodology to generate realistic clutch transfer functions using an advanced engagement bench tester. The test stand is equipped with programmable slip and force controllers to replicate both torque phase and inertia phase of gear shifting. It accommodates a clutch module, not only the clutch pack, to reproduce actual in-vehicle lubrication conditions. The clutch behaviors are characterized for various combinations of operating conditions. The bench test data are compared with SAE#2 data to highlight the sensitivity of hydrodynamic behaviors to force and slip profiles. A regression technique is utilized to represent clutch behaviors as a transfer function in non-linear forms using data from the advanced tester. Shift simulations are conducted to demonstrate the value of realistic transfer functions to enable upfront drivability assessment for control development.
Haria, Hiral, Fujii, Yuji, Pietron, Gregory M., Sun, Anna, Tsuchiya, Takahiro, Miyagawa, Masatoshi, Nakamura, Shinji, Wendel, Matthew, Miyoshi, Hiroya, Wang, Pengchuan, Katopodes, Nikolaos
Torque and Pressure CFD Correlation of a Torque Converter06-12-03-00128/22/2019
A torque converter was instrumented with 29 pressure transducers inside five cavities under study (impeller, turbine, stator, clutch cavity between the pressure plate and the turbine shell). A computer model was created to establish correlation with measured torque and pressure. Torque errors between test and simulation were within 5% and K-Factor and torque ratio errors within 2%. Turbulence intensity on the computer model was used to simulate test conditions representing transmission low and high line pressure settings. When turbulence intensity was set to 5%, pressure simulation root mean square errors were within 11%-15% for the high line pressure setting and up to 34% for low line pressure setting. When turbulence intensity was increased to 50% for the low line pressure settings, a 6% reduced root mean square error in the pressure simulations was seen. For all pressure settings, cavities closer to the converter inlet required a 5% turbulence intensity while the cavities inside or near the torus were better suited with 50% turbulence intensity levels.
De Jesus Rivera, Edward, Woodland, Mark, Robinette, Darrell, Blough, Jason, Anderson, Carl, Frait, Steve, Devendran, Ram
Dual Clutch Transmission Vibrations during Gear Shift: A Simulation-Based Approach for Clunking Noise Assessment2019-01-15536/5/2019
A novel methodology, for the assessment of Dual Clutch Transmission vibrations during gear shifts, is proposed in this paper. It is based on the capability to predict through numerical simulation a typical dynamic quantity used to objectively evaluate the vibrational behavior of a gearbox during experimental tests, i.e. the acceleration of a point on the external surface of the gearbox housing. To achieve this result, a two-step approach is proposed: an accurate simulation of the internal transmission dynamics and an offline uncoupled computation of the gearbox housing acceleration from the output of the simulation. The first step required the definition of a suitable nonlinear lumped parameter model of the car equipped with a DCT that was implemented in Amesim software. The second step, developed as a post processing tool in Matlab, is based on the knowledge of the inertance Frequency Response Functions (FRFs) between a single component of force applied in a bearing and a single component of acceleration in the measurement point. The indices used to assess the clunk severity are peak to peak amplitude and RMS of the gearbox housing acceleration. The effectiveness of this method is proven by comparing experimental and simulated trends of the clunk indices.
Galvagno, Enrico, Dimauro, Luca, Mari, Gianluca, Velardocchia, Mauro, Vella, Angelo Domenico
Analytical Estimation of Clutch Life for Manual Transmission2019-01-03354/2/2019
The clutch is the connecting link between engine and the power train. It connects and disconnects the engine to the gearbox as per the wish of the driver. Clutch has a friction disc which acts like a fuse wire which wears in the process of the connection. This paper tries to calculate the clutch life analytically (In terms of Kms. run by vehicle), of automotive vehicles having manual transmission. As the clutch engages and disengages the engine to the gearbox, during this time due to slippage, energy is dissipated which results in the wear of the clutch disc. It calculates life based on the volumetric wear of the clutch disc and wear allowance available. The work done by other people in this domain include the empirical estimation of clutch life based on the past data, effect of the surface topography on the friction characteristics of the wet clutches, modeling of clutch housing and facing temperature for the estimation of the clutch life of a manual transmission etc. The present work simplifies the estimation of clutch performance using fundamental principles, without high end analysis software or past data. It helps to estimate the clutch performance in the concept stage itself thereby saving time and labor making the selection of the right clutch at the very first time. The complete work was done in-house and its purpose was to estimate the life of the clutch in terms of vehicle run in Kms. The results estimated were closely compared with respect to the field data of vehicles. This tool will be of immense help in such a fast changing automotive world where competition is cut-throat and product development time is shrinking continuously.
Mishra, Anurag, Chollangi, Damodar
A New Analytical Model for Clutch System Modeling and Design Optimization2019-01-08404/2/2019
In manual transmission vehicles, Clutch has direct interaction with the driver and plays a significant role in defining the drivability and NVH of a vehicle. These key performance factors depend on the interaction of diaphragm and cushion springs of a clutch. For an automobile manufacturer, it’s essential to optimize the characteristics of these springs based vehicle performance requirements. A state of the art analytical model has been developed by modeling the diaphragm and cushion spring with exponential equations. Based on these models, response functions for release load, torque build-up, and pressure plate lift have been derived. Results achieved from these response functions are correlated with test data. Key contributing factors for peak clutch pedal load, vehicle launch acceleration, and disengagement point have been identified by sensitivity analysis. Multi-objective optimization is performed to select optimized parameters for vehicle performance improvement
Shandilya, Rahul, Rawla, Vikas
Application of Empirical Asperity Contact Model to High Fidelity Wet Clutch System Simulations2019-01-13014/2/2019
Wet clutches are complex hydrodynamic devices used in both conventional and electrified drivetrain systems. They couple or de-couple powertrain components for applications such as automatic shifting, engine disconnect and torque vectoring. Clutch engagement behaviors vary greatly, depending on design parameters and operating conditions. Because of their direct impact on vehicle drivability and fuel economy, a predictive CAE model is desired for enabling analytical design verification processes. During engagement, a wet clutch transmits torque through viscous shear and asperity contact. A conventional Coulomb’s model, which is routinely utilized in shift simulations, is inadequate to capture non-linear hydrodynamic effects for higher fidelity analysis. Extensive research has been conducted over the years to derive hydrodynamic torque transfer models based on 1D squeeze film or 3D CFD. They are typically coupled with an elastic asperity contact model for mechanical torque transfer. However, the recent advancement reveals no significant asperity deformation at the frictional surface during engagement and establishes a new empirical asperity contact model. This paper describes the integration of the empirical asperity contact model with CFD for developing a high-fidelity wet clutch engagement model. The asperity models are examined in detail for four friction materials to highlight distinct contact behaviors. They are coupled with 3D CFD model in OpenFOAM for engagement simulations, demonstrating the importance of selecting the right asperity model for predictive clutch analysis. A breakdown of hydrodynamic and mechanical torques is provided, enabling numerical examination of clutch engagement processes. Simulation results are compared with clutch module test data that is specifically designed to replicate actual shifting conditions. It is found that accurate simulation of a complete clutch system requires not only engagement physics, but also in-depth understanding of actuator characteristics such as seal drag.
Haria, Hiral, Fujii, Yuji, Pietron, Gregory M., Wang, Pengchuan, Katopodes, Nikolaos, Miyagawa, Masatoshi, Tsuchiya, Takahiro, Nakamura, Shinji, Wendel, Matthew, Miyoshi, Hiroya
Selection of Rational Parameters of Automated System of Robotic Transmission Clutch Control on the Basis of Simulation Modelling2019-01-00291/15/2019
The article deals with the analysis of one of the methods of selecting rational parameters of automated clutch control system for robotic transmission. The objective is to select rational parameters of automated clutch control system for robotic transmission, equipped with electropneumatic actuating mechanism on the basis of mathematical simulation. The depicted mathematical simulation of the clutch control system is characterized by the possibility to coordinate the algorithm of control unit with the dynamic processes in the execution device. The new functional interrelations between the elements of the electro-pneumatic actuator are mathematically described. The way to the selection of rational parameters of an automated control system for clutch is recommended; the selection taking into account the features of the electro-pneumatic actuator. Using the mathematical modeling method, rational control parameters of the automated clutch control system are determined. Based on comparative experimental researches, an inaccuracy is calculated for the mathematical modeling of the processes taking place in the electro-pneumatic actuator of a robotic transmission. Analysis of the results of mathematical modeling allowed finding factors that give a competitive advantage in comparison with automated clutch control systems that are used for commercial purposes.
Mikhalevich, Mykola, Yarita, Alexandr, Leontiev, Dmitry, Gritsuk, Igor V., Bogomolov, Viktor, Klimenko, Valeriy, Saravas, Viktoriya
Performance Optimization of Commercial Vehicle Clutch Actuation System2019-26-03341/9/2019
Rapid changes in competitive automotive market trends and customer expectations have forced automobile manufacturers to offer better products with more distinctive features and improved comfort, all at a lower cost. Occupant comfort within the cabin compartment and easy operation of peripheral controls are some of the important factors under consideration while choosing the vehicle over its competition. In the clutch actuation system, the clutch pedal is the first key customer touch point between driver and vehicle transmission hence its performance is most significant to the overall quality perception and customer appeal. The effect of high clutch pedal effort of the clutch actuation system is felt by the driver during heavy traffic conditions, where frequent gear shifts are required, this becomes an annoyance to the driver decreasing his productivity. In order to afford superior comfort and a smooth clutch feel to the driver during day to day driving, there is a need to optimize the clutch actuation system performance The scope of this paper was to optimize the clutch pedal effort using Taguchi Method in order to meet performance targets and to become superior among benchmark vehicles as well. A Design of Experiments (DOE) analysis has been conducted on the vehicle with respect to selected design variables. Moreover, based on Taguchi technique for single response optimization, the best factor levels are selected for experiment. At the end of these experiments, it has been concluded that the optimal combination of selected variables meets the clutch actuation system performance targets requirement.
Phapale, Sandip
Energy Based Analytical Study of Effect of Engine Calibration, Clutch Modulation on the Life of Dry Clutch in View of City Traffic Using Road Load Data2019-26-03311/9/2019
Single plate dry clutch is one of the most abuse components in the vehicle. With the growing population of traffic in cities, useful life of clutch is affected drastically which is evident from the rise in complaints on clutch from metropolitan cities. The governing design parameter, which affects the life of clutch, is the energy dissipated in clutch per unit area of friction lining of clutch disc. The life of clutch is affected by many factors like vehicle weight, engine torque, driveline ratios, friction lining, size of clutch, which are taken into consideration during design stage of the clutch. Apart from these factors, one more factor, engine calibration, affects the clutch life drastically. However, it is not taken into consideration during design stage owing to its inherent nature as it gets matured over the vehicle development program. Engine calibration, especially driven idle speed calibration of engine in 1st, 2nd and 3rd gear for a particular vehicle, governs the vehicle behavior and drivers maneuvering of clutch, brake and accelerator in city traffic. This paper presents study done using road load data collected in metropolitan city traffics to understand drivers maneuvering in traffic, effect of engine calibrations on typical maneuvering, using energy dissipated in clutch as basis. The paper discusses the effectiveness of changes done in driven idle speed calibration of engine with two vehicle, having different calibrations, driven back to back in city traffic. As energy dissipated in clutch is used as basis, the study indicates avenues in engine calibration for improvement in clutch life.
Mohire, Sujit, Katarki, Shrirang, Chaskar, Mithun, Uttamani, Rahul, Tendulkar, Vishveshvar
Method Development to Virtually Validate Farm Tractor Skid for Front End Loader Application2019-26-00801/9/2019
In farm tractors, front end loaders are becoming popular attachments for primarily material handling such as loading, moving and unloading of woodchips, sand, gravels etc. It is also used for some severe load application such as tree uprooting and ripping operation which requires validation of loader frame and tractor as well. To validate the design, a standard pull-push test is carried out on tractor with loader in a laboratory. In this test front loader bucket is pushed against a rigidly clamped fixture with full engine throttle and maximum hydraulic cylinder pressure of loader. To avoid surprise failures during the test, a virtual simulation method needs to be developed and validated. In this paper, a method has been proposed by authors for the above objective. A multi-body dynamics model of tractor with loader is created in MSC ADAMS and actual event is simulated using test loads & boundary conditions. Forces and moments are extracted on all tractor skid attachments points from MBD model. Afterwards, an inertia relief durability analysis is done in MSC Nastran using the extracted loads. Strain gauges are pasted on tractor front axle support, clutch housing and data acquisition activity is carried to extract strain level during test operation. The durability results are correlated with measured strain data and achieved more than 80% correlation.
Subbaiyan, Prasanna Balaji, Kumar, Abhay, Mayur, Jaju, Nizampatnam, Balaramakrishna, Bhanuprakash, S.A, Schneider, Dave
Study of Clutch Judder Phenomenon in Manual Transmission Vehicle and Its Analysis Approach2019-26-02151/9/2019
Clutch engagement judder is a phenomenon wherein the driver experiences vibrations on seat during the clutch engagement process for the vehicle launch. Clutch engagement judder is one of the critical vehicle attributes as a part of overall vehicle NHV. Torsional oscillations, specifically originating from clutch in the driveline during clutch engagement, are referred as clutch engagement judder. Judder is a phenomenon wherein friction induced torsional vibrations are generated in the driveline because of sliding contact between clutch and flywheel, during engagement. These resulting oscillations inherit the first resonance frequency of the driveline. The engagement judder not only affects the dynamics of transmission system but also the vehicle, because of excitations being transferred to body via suspensions and mounts. Passengers experience these oscillations as vibrations during vehicle launch. If excitation level is high then it may cause discomfort to passengers. In addition to those effects, vibrations generated may cause wear of friction material and thereby reducing performance and life of clutches. In this paper, influencing factors on clutch judder, including internal factors (friction characteristic, damping) and external factors (engine torque fluctuation, applied oil pressure fluctuation, engine mount stiffness), are studied analytically. Thru a typical case study, an approach is proposed to identify the source behind clutch engagement judder on a vehicle and possible ways to eliminate or effectively minimize the engagement judder.
Mohire, Sujit, Kapse, Ravi, Tendulkar, Vishveshvar
Necessity of Advance Damper Technology for Future Agriculture Domain2019-26-01931/9/2019
There is an increasing demand from end-users of tractors for longer clutch durability, reduction in driver fatigue and comfort during field operations. Tractor manufacturers are moving towards Wet Clutch Pack with torsion dampers to meet this emerging customer needs. However, in Conventional Torsion Dampers, there is a technical challenge to withstand harsh clutch engagement or high unexpected impacts of agri-implements, which are common in field operations. This is in addition to, torsional vibrations produced by the power-train. There are constraints, to further optimize a conventional damper without compromising important parameters like factor of safety, noise and durability issues. Hence the proposed next generation damper technology can meet all the new technical requirements and can ensure smooth and durable power shift transmission in tractors. This case study has been done with help of SCHAEFFLER’s tailor made “Tornado Instrument” and “Software” by acquiring real time data (directly from agricultural field operations) from several OEMs followed by quantitative analysis of unexpected impacts, and addressing this issue with next generation damper technology.
Bagadekar, Vijaykumar Shankar, Alavilli, Satya Pavan, Kadhar Maideen, Salim Malik, Rajendran, Ashok Kumar, Radhakrishnan, Padmanaban, Soni, Sandeep
Optimization of the Lubrication Distribution in Multi Plate Wet-Clutches for HVT Transmissions: An Experimental - Numerical Approach2018-01-18229/10/2018
The paper investigates the lubrication flow within multi plate wet-clutches for hydro-mechanical variable transmissions in order to optimize the oil distribution and to reduce the thermo-mechanical stresses on the plates. Since experimental measurements are very difficult to carry out on a real system, CFD numerical tools are used for predicting the flow distribution in a real geometry under actual operating conditions. A modular approach is adopted for the domain subdivision in order to represent accurately the three dimensional geometrical features, while the volume of fluid approach is used to model the multi-phase flow that characterizes the component. Poor lubrication is predicted where high thermal stresses were observed during tests. Furthermore, the numerical modeling is validated against measurements carried out on an ad-hoc designed test rig, which adopts transparent PMMA and 3D-printed inserts for the flow investigation. Fast imaging techniques are used to capture the multiphase flow pattern within the clutch gear chamber. The testing facility replicates both the geometry of a real clutch and the actual operating conditions. A good agreement between the numerical and the experimental results is found and the analysis highlights the importance of modeling the multi-phase nature of the lubrication process for the accurate prediction of the oil distribution within multi plate wet-clutches. By means of the numerical analysis modifications to the inlet flow configuration and to the leakages’ height are developed, leading to a better oil distribution within the clutch and to a more uniform lubrication through the plates clearances.
Terzi, Stefano, Manhartsgruber, Bernhard, Milani, Massimo, Montorsi, Luca
Influence of Clutch Tribodynamics on Drivetrain Noise, Vibration and Harshness, (NVH), Phenomena2018-01-15376/13/2018
Limiting problematic Noise, Vibration and Harshness (NVH) phenomena in the modern automotive drivetrain is a task of critical importance. The result of such phenomena is the aggravation of the driver, which results in a reduced perception of vehicle quality. Each phenomenon can be characterized by a distinct frequency range. The aim of the current study is to assess the influence of the interfacial frictional behavior of the dry friction clutch components on the drivetrain dynamic behavior. The dynamics of the system (in terms of its stability) are studied. Surface data from the clutch components are critical to understanding the complex engagement process. The coefficient of friction was measured using a rotary tribometer at representative slip speeds and contact pressures. To aid the analysis infinite focus microscopy was used to measure the geometric properties of the constituent components of the drivetrain. The current approach allows for improved understanding of the drivetrain’s dynamic behavior. The improved understanding of the coupling between tribological characteristics and drivetrain system dynamics can lead to the mitigation of future NVH issues.
Minas, Ilias, Morris, Nicholas, Theodossiades, Stephanos, O'Mahony, Martin
Interior Noise Refinement in an ICV Bus through Driveline Torsional Vibration Analysis2018-01-14726/13/2018
With a push for urbanization across cities, there is an increased demand for mobility in public transportation especially buses which are provided through state transport undertakings. Hence, the expectations of this class of vehicles will be high in terms of quality and comfort to the passengers. The noise inside the passenger area of the bus becomes an important parameter, which sets apart a bus manufacturer from its competitors. The driveline of the bus is the system responsible for the transfer of power from engine to the wheels. The noise and vibration problems associated with it are detected only in the late stages of the design chain, when all its elements are tested together over a wide range of conditions. Since, calibration of engine and the selection of transmission is freezed in early stages, satisfying power and torque requirements, the only viable option left to address the problem is by optimizing the clutch parameters. Combustion in multi-cylinder four stroke diesel engine produces periodically changing gas and inertia forces associated with reciprocating pistons. This leads to fluctuation in the engine speed and the torque transmitted by the engine, inducing torsional vibrations into the system. These torsional vibrations make the unloaded gear pairs of the gearbox to impact against each other generating Gear rattle noise. In the present work, an abnormal noise was observed in an ICV (Intermediate Commercial Vehicle) bus at both idling and driving conditions. Near source noise measurements and interior noise measurements were carried out to determine the source of the noise. Torsional vibration levels were also measured at engine and gearbox. Upon identification of the source, the clutch parameters including the clutch torsion spring stiffness was scrutinized and modified. This gave improvement in the interior noise levels inside the passenger area of the bus.
Kamani, Keval, Kannan, P, P, Sivaraman
Virtual Simulation for Clutch Thermal Behavior Prediction2018-37-00215/30/2018
The clutch is that mechanical part located in an internal combustion engine vehicle which allows the torque transmission from the shaft to the wheels, permitting at the same time gear shifting and supporting engine revolutions while the car is idling. This component exploits friction as working principle, therefore heat generation is in its own nature. The comprehension of all the critical issues related to thermal emission, and also of the principal physical parameters driving the phenomena are a must in design phases. The subject of this paper is the elaboration of an accurate, but also easy to use and easily replicable, methodology to simulate thermal behavior of a clutch operating inside its usual environment. The present methodology allows to prevent corrective actions in the last phase of the projects (real testing), such as changes in gear ratios, that likely worsen CO2 emissions, permitting to achieve the wished thermal performance of the clutch avoiding late changes. Using computational fluid dynamics, coupled with thermal-FEM software, working limits can be foreseen, and strengths or design flaws can be highlighted. The approach for the problem is typically bottom-up: starting with the simulation of a reduced domain around the clutch and going towards the complete car thermal simulation. Here, the aim is to show the setup of a thermal simulation, considering boundary conditions, initial conditions and geometry details. Starting from a reduced computational domain, many more attempts can be run and a final model more easily found. Consequently, a sensitivity approach to several aspects will be adopted: heat generation location and temperature of different components can be considered to evaluate the impact on the clutch thermal behavior. The paper will show the correlation between experimental and virtual results for both complete and reduced models, to identify the best trade-off between computational efforts and accuracy.
Tosi, Fabio, Gautero, Matteo, Lorefice, Laura, Paola lng, Nicola
Conceptual Design Challenges and Solutions in Power Shuttle Transmission Development for Legacy Tractors2018-01-03944/3/2018
Current developments in tractor transmission design has galloped to new heights with the introduction of CVT, Power shift, Power shuttle, hydrostatic etc besides the vastly available synchromesh and constant-mesh gearboxes. In contrary to the above existing facts of new powertrain development, there is a definite market need to revamp the heritage tractor models to be equipped with the modern transmission systems. This will help customers to have the advanced drivetrain features in the legacy tractors that have won many hearts. One such modernization was the development of new power shuttle transmission in legacy tractor models for TAFE tractors. Power shuttle primarily enables a tractor - in this case, to go forward and reverse by operating a wet clutch. A flick of lever, usually on the steering column changes the direction of the tractor at the same speed of the gear selected. This research work is on the various conceptual drivetrain challenges akin to ground speeds, base drivetrain layout, wheel base, PTO speed, etc conquered with maximum use of existing drivetrain parts. Advanced simulation tools such as KISSsoft, MASTA for new gear design and FEA through ANSYS for shafts have been used where ever necessary. All innovative solutions discussed this research paper led to the design and development of a new, compact, cost effective power shuttle transmission option for legacy tractors with increased operator comfort, productivity, and life compared with the existing manual shuttle transmission.
Rajagopal, MahendraMohan
Development of New Groove Design for Reduction of Drag Torque or Spin Loss of Disengaged Wet Clutches in the High Speed Region2018-01-13004/3/2018
The typical graph of a drag torque or spin loss vs. speed of disengaged wet clutch of automotive transmission shows 4 types of trends. First one is increasing until a peak level, next decreasing to the lowest level, next saturating or being no change, and last again increasing. If the absolute value of drag torque at high speed (6000-20,000rpm) is high, the possibility of fluttering of friction disk, chipping, burning and delamination of friction materials will be high. Moreover, the efficiency of a transmission will be dropped and the life of it become shorter. Therefore, it is important to understand the physics behind the torque jump up at high speed. In our previous study, we investigated the possible reasons of torque jump up at high rotation speed. In this paper, we have extended our previous study and developed new groove design to reduce the drag toque in the high speed range. Result shows that a significant amount of drag torque in the high speed range can be reduced by a new groove design friction disk.
Pahlovy, Shahjada A., Mahmud, Syeda, Ogawa, Makoto
Structural Analysis Based Sensor Placement for Diagnosis of Clutch Faults in Automatic Transmissions2018-01-13574/3/2018
This paper describes a systematic approach to identify the best sensor combination by performing sensor placement analysis to detect and isolate clutch stuck-off faults in Automatic Transmissions (AT) based on structural analysis. When an engaged clutch in the AT loses pressure during operation, it is classified as a clutch stuck-off fault. AT can enter in neutral state because of these faults; causing loss of power at wheels. Identifying the sensors to detect and isolate these faults is important in the early stage of the AT development. A universal approach to develop a structural model of an AT is presented based on the kinematic relationships of the planetary gear set elements. Sensor placement analysis is then performed to determine the sensor locations to detect and isolate the clutch stuck-off faults using speed sensors and clutch pressure sensors. The proposed approach is then applied to a 10-Speed AT to demonstrate its effectiveness. A simulator is developed to qualitatively study the effects of clutch stuck-off faults on speeds of different elements in an AT. Simulator results are presented to support the sensor placement analysis. Later, a comparative analysis of different sensor sets based on the cost and performance is conducted to choose the optimal sensor combination. This paper concludes by discussing in detail the different sensor sets that give different fault isolation performance and suggests that only increasing number of sensors does not guarantee better fault isolation.
Deosthale, Eeshan Vijay, Ahmed, Qadeer, Arasu, Mukilan, Rizzoni, Giorgio, Mohammed, Majed, Hathaway, Richard
General Motors Hydra-Matic 9T50 Automatic Transaxle2018-01-03914/3/2018
General Motors Global Propulsion Systems’ first nine-speed automatic transmission makes its debut in the 2017 Chevrolet Malibu, advancing a legacy of multispeed transmissions designed to optimize efficiency, performance and refinement. The Hydra-Matic 9T50 nine-speed is paired with a Ecotech 2.0L Turbo engine in the Malibu, contributing to an EPA estimated 33 mpg highway, a three-percent increase over the 2016 Malibu with an eight-speed automatic paired to the same engine. The 9T50 has a wider 7.6:1 overall ratio, which is the ratio between the first gear ratio and the top gear ratio, - compared to the six-speed’s 6.0:1 ratio. The 9T50 is fitted with a “deep” 4.69 first gear ratio for excellent off-the-line acceleration and a “tall” 0.62 top gear ratio for low-rpm highway cruising. That balance optimizes acceleration and fuel economy while reducing engine noise during cruising. With nine available forward ratios, the step size between the gears is reduced providing smooth, precise upshifts and excellent refinement. Engineering features like the Selectable One Way Clutch (SOWC), step pinion gear set, and control valves integrated into the pump support allows the 9T50 to package in the same vehicle architectures as the 6T50 six speed automatic. Vehicle integration and packaging costs have been significantly reduced so interchangeability in existing vehicles will be quick and use less capital.
Martin, Thomas, Hendrickson, James
Development of an Analysis Program to Predict Efficiency of Automotive Power Transmission and Its Applications2018-01-03984/3/2018
Prediction of power efficiency of gear boxes has become an increasingly important research topic since fuel economy requirements for passenger vehicles are more stringent, due to not only fuel cost but also environmental regulations. Under this circumstance, the automotive industry is dedicatedly focusing on developing a highly efficient gear box. Thus, the analysis of power efficiency of gear box should be performed to have a transmission that is highly efficient as much as possible at the beginning of design stage. In this study, a program is developed to analyze the efficiency of an entire gearbox, considering all components’ losses such as gear mesh, wet clutches, bearings, oil pump and so on. The analytical models are based on the formulations of each component power loss model which has been developed and published in many existing papers. The program includes power flow analysis of both a parallel gear-train and a planetary gear-train. The program is also implemented with the assumption that the components of power losses are independent of each other. The developed program is employed to estimate the power losses and efficiencies of several automobile gear boxes. The results are then validated by comparing with the experimental data.
Park, Kijong, Kang, Maru, Lee, Jihun, Son, Woo Churl, Harianto, Jonny, Kahraman, Ahmet
Dog Clutch Without Circular Backlash2018-01-12994/3/2018
The paper is dedicated to design of a new dog-clutch gearshift mechanism for passenger car gearboxes with external synchronization. There are two main targets of presented work: 1 Replace the standard synchronizer with cheap and compact shift device, which will keep the internal architecture of classical manual transmission. 2 Keep all the other important functions of synchronizer: a minimal circular backlash to avoid clash during change of sense of the torque flow, b prevent unwanted disengagement, c guarantee the shift anytime, d determine neutral position (preferably). Czech Technical University in Prague is for several years active in the field of design and testing of shift mechanisms, as well as in design of new shift clutches. The currently presented clutch is 3rd generation of inventions of dog clutch systems. All clutches were fabricated as prototype and tested. All designs will be briefly described in the paper. To observe the real life function the prototype was assembled into the passenger car gearbox between the IIIrd and IVth speed. The transmission was equipped with external synchronization device. With help of external synchronization device the different relative speeds between the free rotating wheel and shaft can be preset. The impact of speed difference on shift smoothness can be evaluated with help of vibration measurement. The results were compared with the same gearbox equipped with classical synchronizer. The currently presented clutch minimizes the number of pieces, shortens the length, and lowers the weight and costs of shift clutch with respect to the standard synchronizer.
Achtenova, Gabriela, Jasny, Michal, Pakosta, Jiri
Investigation on Dry-clutch Transmissibility Characteristic for Vehicle Launch Shudder2018-01-12254/3/2018
Vehicle launch shudder is the terminology used in automotive industry to describe severe longitudinal oscillation during clutch engagement under start-up condition. This paper presents and implements detailed investigation for dry-clutch engagement and disengagement process, in order to deeply analyze vehicle launch shudder phenomenon which seriously deteriorates ride comfort. Firstly, diaphragm spring and cushion spring and link strip, which are three elastic components related to dry-clutch engagement and disengagement process in axial direction, are studied for their elastic properties, respectively, to obtain relationship between load and deflection. The elastic properties of these three elastic components are taken into considerations to establish nonlinear relationship between release bearing travel and clutch clamp force. Then, based on multi-body system dynamics theory, the lumped mass method is used to model the powertrain of front-engine and front-wheel-drive vehicle equipped with manual transmission, six-degree-of-freedom powertrain torsional vibration model is used to simulate vehicle launch shudder phenomenon numerically, and the performance of vehicle launch is evaluated by shock extent and dissipated energy. The speed of release bearing travel is used to reflect different launch intentions: fast launch and normal launch and slow launch. Finally, by comparing evaluation parameters of these three launch modes, it can be known that the longer synchronous moment or release bearing travel time, the smaller shock extent, and the better launch performance, but dissipated energy is negatively correlated with shock extent. Through the research of this paper, the launch shudder during dry-clutch engagement process is analyzed, which can provide theoretical references for structural optimization and launch control strategy.
Yuan, Renfei, Wu, Guangqiang
Performance Optimization of Compressor Rotor Clutch Sub-assembly Using Electro- Magnetic Analysis2018-01-04844/3/2018
Rotor Clutch sub-assembly is one of the very important sub-assemblies (S/A) of an automotive compressor as it delivers the required torque/power to run the compressor. It mainly consists of rotor and bearing, stator, hub and armature. Rotor is rotated by engine pulley through belt drive system, while stator housing has got number of coils winded around stator slot. The hub sub-assembly is attached to the compressor shaft via spline arrangement and bolted across. When direct current (DC) is supplied to the terminal of the rotor, an electromagnetic field is generated which causes to attract the hub part towards rotor. Once the hub and rotor gets engaged each other, torque is transmitted to the compressor shaft which then helps to complete the suction and compression of refrigerant gas and thus making the vapor cycle run to produce adequate cooling in the air-conditioning (AC) system. Hence it is most important to ensure adequate and even distribution of electromagnetic field which is solely responsible for providing torque to the compressor. The present paper describes the numerical simulation of electromagnetic field of a clutch sub-assembly of an automotive compressor. ANSYS software was used to simulate the same. 2dimensional geometry of clutch rotor sub-assembly was created from computer aided design (CAD) tool and imported in suitable format. Meshing was performed using shell elements and the necessary material properties like permeability and B-H curve were defined along with the load conditions. The obtained flux density was then optimized by changing the shape and size of clutch sub-assembly. Further to this shaft torque was calculated analytically using the numerically obtained flux density and validated with the required torque for compression/suction process. The validation results exhibit a good trend and correlation, thus helping to develop a procedure to design clutch sub-assembly ‘first time right’ at the design stage. It is also ensured by this to have adequate torque delivered to the compressor.
Meena, Avadhesh, Sen, Somnath
Simulation to Estimate the Output Torque Characteristics and Temperature Rise of a Transmission Wet Clutch during the Engagement Process2018-01-04024/3/2018
During a typical shift event, one or more clutches are brought to engagement while others are released in order to change the torque transmission path. A mismatch in torque level and handshake timing between the off-going and on-coming clutches affects the shift quality. In order to capture the dynamic behavior of the torque response and estimate the temperature rise at the friction disk and separator plate interfaces during the engagement process, several numerical models have been developed. The earliest of these models was presented by Berger et al. which was later modified and enhanced by Natsumeda et al. and Yang et al. However, these models cannot capture the dynamic behavior of grooved clutch disks. Hence, development of a wet clutch engagement simulation model using commercial CFD simulation tool, which can capture the dynamic behaviors of no groove and grooved disks, becomes a pressing need. In this paper, we have presented an engagement simulation model using Star CCM+ simulation software and also discussed our observations from the simulation results. The key input parameters are squeeze velocity of the oil film, oil inlet temperature, initial rotating speed and flow rate. The porosity of the friction materials, friction co-efficient, compressive strain and flow factors are also taken into account. Our simulation model provides a helpful means to realize the influence of oil flow rate, rotating speed, applied pressure and groove patterns on the output torque behavior and temperature rise.
Mahmud, Syeda Faria, Pahlovy, Shahjada A., Ogawa, Makoto
Derivation of Test Schedule for Clutch Using Road Load Data Analysis and Energy Dissipation as Basis2018-01-04044/3/2018
During every clutch engagement energy is dissipated in clutch assembly because of relative slippage of clutch disc w.r.t. flywheel and pressure plate. Energy dissipated in clutch is governed by many design parameters like driveline configuration of the vehicle vis-a-vis vehicle mass, and operational parameters like road conditions, traffic conditions. Clutch burning failure, which is the major failure mode of clutch assembly, is governed by energy dissipation phenomenon during clutch engagement. Clutch undergoes different duty cycles during usage in city traffic, highways or hilly regions during its lifetime. A test schedule was derived using energy dissipated during every clutch engagement event as a base and using road load data collected on the vehicle. Road load data was collected in different road mix conditions comprised of city traffic, highway, hilly region, rough road for few hundred kilometers. Using this data clutch energy was calculated in all the clutch engagement events observed in road load data. Cumulative energy calculated from all these events was extrapolated for stated life of the clutch, for vehicle application under consideration. A test cycle was derived considering maximum energy dissipated in engagement events, clutch engagement pattern and maximum temperature observed inside clutch housing, for rig testing. The life predictions and failure modes observed with this test schedule were evaluated against the field vehicles and it showed a good correlation. This paper proposes a methodology to derive test schedule for clutch life prediction based on energy dissipated in clutch and using road load data. The test on the rig with such schedules provides better avenues to shorten the development time line of clutch system as well as vehicle driveline.
Mohire, Sujit, Uttamani, Rahul, Tendulkar, Vishveshvar, Katarki, Shrirang, Patil, Shahaji
Clutch Installation and Release Linkage Requirements for Truck and Bus ApplicationJ2407_201711 (Current)11/3/2017
Although not limited to, these installations are normally used on trucks considered as Medium Duty (Class 6 and 7), as well as Heavy Duty (Class 8).
Truck and Bus Powertrain Committee
A New Rotating Wedge Clutch Actuation System2017-01-244110/8/2017
Rotating clutches play an important role in automatic transmissions (AT), dual-clutch transmissions (DCT) and hybrid transmissions. It is very important to continually improve the transmission systems in the areas such as simplifying actuator designs, reducing cost and increasing controllability. A new concept of electrical motor driven actuation using a wedge mechanism, a wedge clutch, demonstrates potential benefits. This wedge clutch has the characteristics of good mechanical advantage, self-reinforcement, and faster and more precise controllability using electrical motor. In this paper, a new rotating wedge clutch is proposed. It presents a challenge since the motor actuator has to be stationary while the clutch piston is rotating. A new mechanism to connect the motor to the wedge piston, including dual-plane bearings and two mechanical ramp linkages, is studied. The design and verification of the physical structure of the actuator are discussed in detail in the paper.
Ding, Zhao, Chen, Li, Yin, Chengliang, Yao, Jian, Lee, Chunhao, Samie, Farzad
Electronic Bi-Directional Shift Control Design and Calibration for Farm Vehicle2017-01-220510/8/2017
Agricultural tractors are often subjected to various applications like front end loading work, cultivation work, where frequent forward and reverse gears are needed. Most of Indian agricultural tractors are equipped with mechanical transmission system which demands repeated clutching and de-clutching operation for such applications resulting in increased operator fatigue and lesser productivity. Also need of electronics in Indian agricultural industry for better farm mechanization is growing high. This research work depicts development of electronic bi-directional shifting (power shuttle) control design and calibration for farm vehicle fitted with wet clutch transmission. This research also reduces operator fatigue via frequent directional shift through electronic transmission. The control system is designed without any electronic interfacing with engine and also provides clutch-less gear shifting and auto-launch which offers ease to drive even for novice driver. The power shuttle transmission control system offers more functionality and features in adjunct to in-built safety features without any additional sensors or components. Use of minimal sensor for system control and calibration delivers cost effect solutions. Adaptive control strategy is adopted for achieving efficient and optimal clutch fill modulation which is calibrateable for various climatic zone, vehicle loads, gears etc. Control software is designed by considering the vehicle variants pertinent to clutch load and engine characteristics. Modular control system design is employed in this research which can be extended across all tractor variants.
M A, Velmurugan, Rajagopal, MahendraMohan
Statistical Modeling of Plate Clearance Distribution for Wet Clutch Drag Analysis06-11-01-000710/8/2017
Wet clutch packs are the key component for gear shifting in the step-ratio automatic transmission system. The clutch plates are coupled or de-coupled to alter gear ratios based on the driver’s actions and vehicle operating conditions. The frictional interfaces between clutch plates are lubricated with automatic transmission fluid (ATF) for both thermal and friction management. In a 10-speed transmission, there may be as many as 6 clutch packs. Under typical driving conditions, 2 to 3 clutch packs are open, shearing ATF and contributing to energy loss. There is an opportunity to improve fuel economy by reducing the associated viscous drag. An important factor that directly affects clutch drag is the clearance between rotating plates. The axial position of clutch plates changes continuously during operation. It is known in practice that not only the total clearance, but also its distribution between the plates affects the viscous drag. However, it is very difficult to measure the actual distribution for every clutch in a running transmission. Because of the limited theoretical understanding of plate movement, a fine tuning of clutch clearance design is often conducted based on trial and error during a vehicle’s development process. This article describes a statistical method for modeling the distribution of the plates in a clutch pack. The proposed method employs order statistics to represent dynamically-changing plate positions. A simulation study is conducted to investigate the effects of plate movement on open clutch drag in the slip region where ATF is present at the interface. It is shown that the model can predict the difference in drag torque with or without fixed clutch plates. The simulation results compare satisfactorily with experimental data. The model provides a mathematical insight into complex plate behaviors for open clutch drag torque analysis. The use of such a statistical model improves the fidelity of a drive cycle simulation for up-front examination of drivetrain efficiency, thus practitioners can take the impact of clearance into consideration when calibrating open clutch models.
Wang, Pengchuan, Katopodes, Nikolaos
Clutch Application Powertrain Startability Rating Requirements for Truck and Bus ApplicationsJ2469_201709 (Current)9/19/2017
Although not limited to, these installations are normally used on trucks considered as Medium Duty (Class 6 and 7), as well as Heavy Duty (Class 8).
Truck and Bus Powertrain Committee
Recommended Remanufacturing Procedures for Manual Transmission Clutch AssembliesJ1915_201708 (Current)8/22/2017
This SAE Recommended Practice is prepared as a guideline to improve and maintain the quality of remanufactured automotive products. Installation of remanufactured or rebuilt products is often an economical way to repair a vehicle even though they may not fully be equivalent to original equipment parts. Before processing any part, a remanufacturer should determine if the original design and present condition of the core are suitable for remanufacturing, so as to provide durable operation of the part as well as acceptable performance when installed in a vehicle. The remanufacturer should also carefully consider the safety aspects of the product and any recommendations of the original manufacturer related to remanufacturing or rebuilding their product.
Truck and Bus Powertrain Committee
SAE Nodal MountJ1134_201708 (Current)8/14/2017
This SAE Recommended Practice establishes a single bolt pattern for the No. 1 clutch housing (see Figure 1) and the No. 2 clutch housing (see Figure 2). These four bolt patterns are designated to give commonality of mounting brackets in existing frame rails. The 420 mm (16.5 in) span, pad face to pad face, allows the ease of installation in existing frame rail widths. This is also the minimum spacing which will accommodate commonly used clutches.
Truck and Bus Powertrain Committee
Tribodynamics of a New De-Clutch Mechanism Aimed for Engine Downsizing in Off-Road Heavy-Duty Vehicles2017-01-18356/5/2017
Clutches are commonly utilised in passenger type and off-road heavy-duty vehicles to disconnect the engine from the driveline and other parasitic loads. In off-road heavy-duty vehicles, along with fuel efficiency start-up functionality at extended ambient conditions, such as low temperature and intake absolute pressure are crucial. Off-road vehicle manufacturers can overcome the parasitic loads in these conditions by oversizing the engine. Caterpillar Inc. as the pioneer in off-road technology has developed a novel clutch design to allow for engine downsizing while vehicle’s performance is not affected. The tribological behaviour of the clutch will be crucial to start engagement promptly and reach the maximum clutch capacity in the shortest possible time and smoothest way in terms of dynamics. A multi-body dynamics model of the clutch system is developed in MSC ADAMS. The flywheel is introducing the same speed and torque as the engine (represents the engine input to the clutch). The hydraulic pressure is applied behind the piston to initiate the engagement. The angular motion of the plates is supported by friction torque between the plates and friction linings. The conjunctions between paper-based linings and steel plates are designed to be dry. Friction (the most significant tribological feature of the linings in torque transmission) is measured in a pin-on-disc tribometer and mapped into the dynamics model in MSC ADAMS. The pin-on-disc tribometer is able to capture the variation of friction coefficient with contact pressure and sliding velocity. The surface topography is obtained experimentally to examine the consistency of surface properties. The normal pressure and tribology of the contacting components determines the engagement time, clutch capacity and dynamic behaviour of the clutch.
Dolatabadi, Nader, Rahmani, Ramin, Theodossiades, Stephanos, Rahnejat, Homer, Blundell, Guy, Bernard, Guillaume
Optimisation of Engine Mounting System for Reduction in Lateral Shake and Drive Away Shudder on Vehicle2017-01-18226/5/2017
In this study we will be discussing two issues related to vibrations which effect car owners. The first one, called lateral shake, can be described as a lateral vibration felt by customer in low speed of around 1200rpm, when vehicle shakes severely in Y-direction. The vibration is significantly felt at the thighs of passengers. A 16DOF rigid body model is established to simulate the power train & body system. The second vibration issue, called drive away shudder (also known as clutch judder/chatter/shudder) is a vibration felt by customers at the time of marching off. The vibration is significantly felt at the time of clutch engagement as a shiver in vehicle. While the common solution of shudder is to optimize clutch friction & engagement, in this study solution has been provided by optimizing the power train mounting system. Clutch shudder is observed on a medium sized car when driven in the range of 10-20 Km/h. The design of powertrain mounting system has been modified to achieve the reduction in above mentioned vibrations. The pros & cons of the suggested change in mounting system on the overall NVH performance is also discussed.
Agarwal, Kopal, Hazra, Sandip
Torsional Vibration Analysis of Six Speed MT Transmission and Driveline from Road to Lab2017-01-18456/5/2017
When a manual transmission (MT) powertrain is subjected to high speeds and high torques, the vehicle driveshaft, and other components experience an increase in stored potential energy. When the engine and driveshaft are decoupled during an up or down shift, the potential energy is released causing clunk during the shift event. The customer desires a smooth shift thus reduction of clunk will improve experience and satisfaction. In this study, a six-speed MT, rear-wheel-drive (RWD) passenger vehicle was used to experimentally capture acoustic and vibration data during the clunk event. To replicate the in-situ results, additional data was collected and analyzed for powertrain component roll and pitch. A lumped parameter model of key powertrain components was created to replicate the clunk event and correlate with test data. The lumped parameter model was used to modify clutch tip-out parameters, which resulted in reduced prop shaft oscillations. By reducing the prop shaft oscillations the clunk phenomena can be reduced and customer satisfaction increased.
Furlich, Jon, Blough, Jason, Robinette, Darrell
Vibro-Impact Analysis of Manual Transmission Gear Rattle and Its Sound Quality Evaluation2017-01-04033/28/2017
Experimental schemes, frequency characteristics, subjective and objective sound quality evaluation and sound quality prediction model establishment of a certain mass-production SUV (Sport Utility Vehicle, SUV) manual transmission gear rattle phenomenon were analyzed in this paper. Firstly, vehicle experiments, including experiment conditions, vibration acceleration sensor and microphone arrangements and especial considerations in experiments, were described in detail. Secondly, through time-frequency analysis, broadband characteristics of manual transmission gear rattle noise were identified and vibro-impact of gear rattle occurs in the frequency range of 450~4000Hz on the vehicle idle condition and the creeping condition. Thirdly, based on bandwidth filtering processing of gear rattle noise, subjective assessment experiments by a paired comparison method were carried out. Evaluation results passed triangular loop verification and Spearman correlation coefficient examination, and then subjective annoyance results of each noise sample were calculated. Further, objective evaluation results, based on two physical acoustics parameters and six psychological acoustics parameters, were obtained respectively. Finally, comprehensive evaluation of subjective and objective results was analyzed by the MLR (Multiple Linear Regression, MLR) method. It’s concluded that AI (Articulation Index) was the appropriate parameter that’s closely related to subjective annoyance results, and correlation coefficient of AI and subjective annoyance results was up to 0.948. Sound quality prediction model of gear rattle was then established on the vehicle idle condition and the creeping condition. Overall in this paper, research achievements could be adopted to solve practical engineering problems (especially gear rattle problem), and furthermore it could reduce R&D (Research and Design, R&D) cycle, labor costs and material costs dramatically.
Wu, Guangqiang, Wu, Huwei
Analysis of Engine Flywheel Wobbling Vibration2017-01-10233/28/2017
Large axial displacement at the edge of a flywheel causes a clutch to fail to disengage in high-speed rotation. To find out the root cause, a numerical procedure is proposed to investigate the vibration source and to understand dynamic behavior of the crank-train system. A simulation of the whole engine system including block, crankshaft, piston, and connecting rod was performed with AVL/Excite. The resulting CAE baseline model had good correlation with measurements. A comprehensive study was conducted for a set of flywheel and crankshaft models with different materials and unbalanced masses. The contribution to flywheel wobbling of each vibration order was carefully investigated, and an optimal design was presented.
Jiang, Yaqun, Hsieh, C., Festag, Georg, Ahmed, Masood, Jiang, William
Two-Phase MRF Model for Wet Clutch Drag Simulation2017-01-11273/28/2017
Wet clutch packs are widely used in today’s automatic transmission systems for gear-ratio shifting. The frictional interfaces between the clutch plates are continuously lubricated with transmission fluid for both thermal and friction management. The open clutch packs shear transmission fluid across the rotating plates, contributing to measurable energy losses. A typical multi-speed transmission includes as many as 5 clutch packs. Of those, two to three clutches are open at any time during a typical drive cycle, presenting an opportunity for fuel economy gain. However, reducing open clutch drag is very challenging, while meeting cooling requirements and shift quality targets. In practice, clutch design adjustment is performed through trial-and-error evaluation of hardware on a test bench. The use of analytical methodologies is limited for optimizing clutch design features due to the complexity of fluid-structure interactions under rotating conditions. This article presents a two-phase Multiple Reference Frame (MRF) CFD model for simulating wet clutch behaviors, accounting for detailed design geometry. The model employs the Volume of Fluid (VOF) method to determine the air-fluid interface inside a computational domain. Model setup and simulation parameters, including initial conditions, boundary conditions, and relaxation factors are evaluated in terms of convergence behaviors. The model capabilities are validated against experimental data. Convergence of the CFD solver is demonstrated, capturing peak drag location as a function of rotating speed, until the phase fraction drops to a small value. The CFD model provides analytical insight into complex fluid interactions for grooved rotating plates, complementing hardware-based clutch design processes.
Fujii, Yuji, Wang, Pengchuan, Katopodes, Nikolaos
A New Unique Approach to Predict the Usable Clutch Life on Utility Vehicles for Driving Conditions Similar to that of Indian Subcontinent2017-01-11283/28/2017
To ensure a robust, reliable and durable product, predicting the useful life of aggregates at the concept stage is a very important aspect in the any product design. This requirement is very much necessary in today’s competitive environment, wherein the customer expectations are increasing and development time for reliable product is shrinking. Clutch is one of the important aggregate in an automobile having manual transmission. It acts like a fuse in the driveline system wherein its wear and tear cannot be avoidable. The performance of Clutch is correlated with its useful life. In this paper, a unique methodology is formulated for the prediction of beta life of clutch. Actual field data of over 3 to 4 years related with warranty claims, mode of failures, usage kilometers etc. has been collected on a typical utility vehicle platform which has been operating on roads of Indian subcontinent. By analyzing the warranty and supplementary data for a given vehicle configuration, relation between the beta life and vehicle parameters influencing the wear and tear of clutch like heat stress has been formulated. This approach can be used as a design guideline to predict the usable clutch life in the design stage with a fair amount of reliability for driving conditions similar to that of Indian subcontinent.
Gorwade, Yuvraj Y., Damami, Anand S.
An Advanced Automatic Transmission with Interlocking Dog Clutches: High-Fidelity Modeling, Simulation and Validation2017-01-11413/28/2017
Fuel economy regulations have forced the automotive industry to implement transmissions with an increased number of gears and reduced parasitic losses. The objective of this research is to develop a high fidelity and a computationally efficient model of an automatic transmission, this model should be suitable for controller development purposes. The transmission under investigation features a combination of positive clutches (interlocking dog clutches) and conventional wet clutches. Simulation models for the torque converter, lock-up clutch, transmission gear train, interlocking dog clutches, wet clutches, hydraulic control valves and circuits were developed and integrated with a 1-D vehicle road load model. The integrated powertrain system model was calibrated using measurements from real-world driving conditions. Unknown model parameters, such as clutch pack clearances, compliances, hydraulic orifice diameters and clutch preloads were estimated and calibrated. Simulation results, such as vehicle acceleration, turbine speed, and output shaft speed, are reported and compared with the measured data to validate the transmission model. Subsequently, the transmission model was coupled with internal combustion engine and road load models. This arrangement permitted investigating the dog clutch engagement dynamics under transient conditions. The relative speed of the dog clutch halves was found to be highly sensitive to the transmission input torque, which indicates that a precise engine torque control schemes are necessary for successful engagement.
Alzuwayer, Bashar, Prucka, Robert, Haque, Imtiaz, Venhovens, Paul
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