Browse Topic: Wet disc clutches

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Tractor Clutch wear simulation by Inhouse development2026-26-05721/16/2026
To develop an accelerated Clutch test simulation method at inhouse laboratory as System level of validation to replicate field phenomena in short time with controlled repeatability and increased test accuracy. Wet clutch is one of the M&M technology project for higher hp(75) tractors. Currently Mahindra having dry clutch system in higher hp tractors & presently Wet clutch development in progress for higher HP tractors for increasing clutch life & to reduce clutch pedal operation as per customer requirement, hence new test rig to be developed for validating new tractor wet clutch system as per RWUP. Previously tractor clutch system is completely evaluated through field testing on tractor level. Thus, there are several drawbacks in field testing like more waiting time to avail seasons, more testing time, evaluation of limited number of samples, non-availability of complete tractor on time, less accuracy, less repeatability of test results, unsafe conditions of rider, higher human fatigue
D, Yashwanth, Raja, R, Udayakumar, S, M, Jeevaharan, Vijayakumar, Narayanan
Uncertainty Quantification of Wet Clutch Actuator Behaviors in P2 Hybrid Engine Restart Process2022-01-07913/29/2022
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 2022-01-02533/29/2022
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 2022-01-07863/29/2022
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 Lubrication2022-01-07883/29/2022
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
Modeling and Design of a Wet Clutch Offset Compound Gear Transmission for Dual-Speed Rotorcraft ApplicationsF-0076-2020-1633610/5/2020
This paper develops a lumped-parameter multi-plates wet clutch Offset Compound Gear (OCG) transmission dynamics and its thermal model for dual-speed rotorcraft applications with an active clutch slip-speed control. This model includes the Reynolds equation for the clutch oil film thickness, the clutch thermal model, the clutch transferred torques (viscous and asperity torque) and the clutch disengagement model. The wet clutch/OCG transmission system is implemented in Matlab® Simulink™ to manage the upshift clutch temperature rise, which is a main issue need to handle for a dual-speed helicopter transmission. Here, the clutch temperature rise is treated by injecting a certain amount of coolant during engagement so that the temperature rise for the wet clutch is much lower than that of an dry clutch. In order to transfer a required torque using the available power, the sizing of the wet clutch could be evaluated via the developed wet clutch/OCG transmission model. This study shows that
DeSmidt, Hans, Bill, Robert, Su, Xiaowen, Smith, Edward
Effect of Wear on Frictionally Excited Thermoelastic Instability2020-01-162910/5/2020
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
Modeling and Parameter Estimation of Automatic Transmission for Heavy-Duty Vehicle Using Dual Clutch Scheme2020-01-22429/15/2020
This paper focuses on modeling of the heavy-duty vehicle drivetrain with automatic transmission by using dual clutch scheme. The planetary gear set in the automatic transmission is complicated structure and difficult to understand. The advantage of the dual clutch scheme is that it can be used to represent the complex planetary gear set intuitively, which is a great help to understand the gear shifting process. It is also suitable for being used in the controller due to its low order. Some conditions are required to convert the planetary gear set to the dual clutch model. The heavy-duty vehicle driveline can be converted to the dual clutch model due to its heavy engine and vehicle inertia. This paper also proposes system parameter estimation methods to represent the driveline model. The main parameters are lumped inertia, lumped gear efficiency, output shaft compliance and friction coefficient of clutches. First, a method for estimating lumped inertia and lumped gear efficiency is
Lee, Tae Heon, Choi, Seibum
Coordination Control Strategy for Mode Switching of a Parallel Hybrid Electric System Based on Continuously Variable Transmission02-13-02-00108/11/2020
This study aims to solve the problem of impact in a parallel hybrid electric system based on the continuously variable transmission (CVT) during switching from pure electric mode to engine-driven, power-generating mode. Taking into account the torque response characteristics of the engine and motor and the dynamic characteristics of the wet clutch hydraulic control system, the mode switching process is divided into six stages, namely, pure electric mode, wet-clutch free travel, engine start-up, engine speed synchronization, clutch combination, and engine intervention drive. A coordination control strategy is developed based on the model predictive control algorithm to ensure smooth mode switching. The effectiveness of the control algorithm is verified using Matlab/Simulink and the AMESim co-simulation platform. Results show that with the mode switching coordination control strategy, the components of the system work harmoniously. The maximum impact is reduced by 52.0% at the speed
Zeng, Xiaohua, Li, Xiaojian, Dong, Bingbing
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
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
Haria, Hiral, McCallum, James, Fujii, Yuji, Tsuchiya, Takahiro, Miyagawa, Masatoshi, Nakamura, Shinji, Wendel, Matthew, Katopodes, Nikolaos
Optimized Control of Dynamical Engine-Start Process in a Hybrid Electric Vehicle2020-01-02684/14/2020
Engine start while driving is one of the most typical and frequent work conditions for hybrid vehicles. Engine start has very significant impact on the driving comfort. Engine start, especially a dynamical engine start, have high control requirements regarding control time, torque output and riding comfort. In some hybrid transmissions such as P2, engine is cranked and synchronized through wet clutch slipping. Because clutch pressure control has time-varying delay and estimation precision of engine torque by ECU (Engine Control Unit) is poor, conventional PID controller is unable to meet the high requirements of control quality. A new control algorithm is proposed in this paper to cope with all these challenges. The new control algorithm is based on LADRC (Linear Active Disturbance Rejection Controller) and is improved through combination with Smith predictor and Adaline network. LADRC is adopted to reduce negative effects of poor precision of engine torque. Smith predictor is
Gao, Ji, Lou, Diming, Zhang, Tong
Dynamics and Control of Gearshifts in Wet-Type Dual Clutch Transmission for BEVs2020-01-07674/14/2020
The dual clutch transmission is one of the possible choices for electric vehicle drivelines. The basic principle and control mode of shifting of wet dual clutch transmission are introduced, and the dynamic process of shifting of wet double clutch transmission is studied. Combined with the dynamic model of the wet clutch engagement process, the difference between the dynamic characteristics of the dual clutch transmission modeling using the Coulomb friction model and the dual-clutch transmission model using the average flow model and the micro-convex contact theory is analyzed. The shift control strategy of the dual clutch transmission proposes a correction method to improve the shifting smoothness. Studies have shown that the torque response of the wet clutch has significant hysteresis, and the improved control algorithm can significantly improve the shifting smoothness of the wet dual clutch transmission. Based on the dynamic model of the wet clutch, the torque interruption of the
Lou, Zhenxiong, Duan, Yupeng, Zhang, Yunqing
Testing of a wet plate clutch system for anti-shudder performance2020-01-05604/14/2020
The wet clutch system ( WCS ) is a complex combination of friction plates, separator plates and lubricant. The basic function of the WCS is to transfer torque under various operating conditions such as slipping, shifting, start/launch and/or torque converter clutch operation. During these conditions the slope of the coefficient of friction versus slip speed ( µ-V ) curve must be positive to prevent shudder of the WCS. A test procedure is needed to evaluate the WCS over a durability duty cycle to monitor the µ-V curve slope and shudder potential. The clutch plates and fluid must be tested together and remain together during the test to evaluate as a WCS. The objective of this paper is to describe this new test procedure which builds on the basics of the SAE J2964 - Low Speed Continuous Slip µ-PVT test procedure but a duty cycle is added to age the WCS. The test includes measurement of the µ-V slope at several intervals during the test ( before break in, after break in, and after each 12
Diemer, Larry, Bares, Jason, Greening, Brent, Ezanno, Philippe, Whitticar, David, Klotchikhine, Vladimir, Greening, Charles
Mathematical Analysis of Clutch Thermal Energy during Automatic Shifting Coupled with Input Torque Truncation2020-01-09674/14/2020
A step-ratio automatic transmission alters torque paths for gearshifting through engagement and disengagement of clutches. It enables torque sources to run efficiently while meeting driver demand. Yet, clutch thermal energy during gearshifting is one of the contributors to the overall fuel loss. In order to optimize drivetrain control strategy, including the frequency of shifts, it is important to understand the cost of shift itself. In a power-on upshift, clutch thermal energy is primarily dissipated during inertia phase. The interaction between multiple clutches, coupled with input torque truncation, makes the decomposition of overall energy loss less obvious. This paper systematically presents the mathematical analysis of clutch thermal energy during the inertia phase of a typical single-transition gearshift. In practice, a quicker shift is generally favored, partly because the amount of energy loss is considered smaller. However, the analysis reveals that there is a critical input
Zhang, Yijing, Fujii, Yuji, Hippalgaonkar, Rohit, Cvok, Ivan, Ivanovic, Vladimir, Deur, Josko, Ranogajec, Vanja
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
Bhone, Nitin, Thakare, Sachin, Jahagirdar, Ashutosh
Inside Tremec's SUPERCAR DCT20AUTP02_041/1/2020
To polish the 2020 mid-engine Corvette's driving prowess, GM and Tremec engineers joined forces to create a new and better automated transaxle. Explaining Corvette's move to one transmission for all buyers, global chief engineer Tadge Juechter notes, “Our customers began requesting a dual-clutch automatic transmission [DCT] several years ago. Following the introduction of the C7 Corvette in 2014, our take-rate for sticks [manual gearboxes] fell from 50 percent to less than 20 percent this year.” Searching the globe - read Europe - for a suitable DCT, Juechter's team found none with sufficient torque capacity to survive behind the lively LT2 6.2-L V8 planned for the all-new 2020 mid-engine edition of GM's reimagined sports car. To solve that dilemma, discussions began with Tremec, the Mexico City-based manufacturer which has supplied GM, Ford and FCA with manual transmissions for two decades. While Tremec had the expertise to make the mechanical components packed inside a dual-clutch
Sherman, Don
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
Haria, Hiral, Fujii, Yuji, Pietron, Gregory M., Sun, Anna, Tsuchiya, Takahiro, Miyagawa, Masatoshi, Nakamura, Shinji, Wendel, Matthew, Miyoshi, Hiroya, Wang, Pengchuan, Katopodes, Nikolaos
Integrated Multi-Physics Simulation for Full-Vehicle Low Frequency NVH Optimization in HEVs2019-01-14556/5/2019
The recent automotive industry trend towards electrification has created new challenges for NVH engineers. These challenges stem from new powertrain architectures and their complex interactions, the governing control strategies which aim to optimize energy management, and new unmasked sources of excitation. Additionally, vehicle manufacturers are attempting to reduce hardware testing in order to rapidly satisfy increasing production demand and to minimize its costs. Hence, to meet the above-mentioned challenges up front in the development process of Hybrid Electrical Vehicles (HEVs) while balancing competing design objectives of drivability, durability and NVH, a simulation-led design and optimization is required. NVH problems are often the result of mechanisms that originate through complex interactions between different physical domains (flow, electromagnetic, structural/mechanical, control logic, etc.) and the assembly of individual components into a complete system. Therefore
Gomez, Llorenc Foraste, Zeman, Jonathan, Liu, Jack
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
Mishra, Anurag, Chollangi, Damodar
Development of a Low Loss Clutch for CVT Reverse Function2019-01-07744/2/2019
Continuously variable transmissions (CVT) provide superior fuel economy by enabling internal combustion engines to operate at their “sweet spots”. However, there is still potential to improve CVT system’s mechanical efficiency, and further enhance vehicle-level fuel economy. In the past, extensive research work has focused on the core continuously variator unit (CVU) that includes pulleys and a belt or chain. Another thread of research has centered on optimization of CVT clamping force control to reduce hydraulic system loss. Nonetheless, to the best of our knowledge, very little research has looked into the planetary gear sets and clutches that enable the CVT system to switch between forward, neutral and reverse gears. The state-of-the-art reverse clutch usually consists of multiple friction and steel plates, and is normally open during all forward driving maneuvers. The relative speed between friction and steel plates is identical to turbine speed, which generate spin loss. We
Duan, Chengwu, Lee, Chunhao, Yao, Jian, Samie, Farzad, Huang, Ying
Modeling, Control, and Adaptation for Shift Quality Control of Automatic Transmissions2019-01-11294/2/2019
The parameters determining shift quality control in automatic transmissions are determined as part of the calibration of the transmission control. The resulting control system typically has three components: feedforward control, where the control output is determined before a gearshift; feedback control, where the control output is determined during the gearshift based on sensed feedback; and learning control (adaptation), where the feedforward or feedback controller parameters are modified after the current gearshift has ended and before the next similar gearshift begins. Gearshifts involving the same ratio change are referred to here as similar gearshifts, though such gearshifts may involve differences in other variables such as vehicle speed or engine torque. In most automatic transmissions, gearshifts are controlled by hydraulic clutches, and operating conditions for these clutches may vary widely, requiring a dedicated transmission controller involving significant calibration
Mishra, Kirti Deo, Cardwell, Gilbert, Srinivasan, Krishnaswamy
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
Haria, Hiral, Fujii, Yuji, Pietron, Gregory M., Wang, Pengchuan, Katopodes, Nikolaos, Miyagawa, Masatoshi, Tsuchiya, Takahiro, Nakamura, Shinji, Wendel, Matthew, Miyoshi, Hiroya
Coordinated Mode Transition Control for a Novel Compound Power-Split Hybrid Electric Vehicle2019-01-13064/2/2019
Because of the direct connection between the compound power split hybrid transmission (CPSHT) and the engine in hybrid electric vehicle (HEV), engine ripple torque (ERT) can lead to obvious jerks when the mode transition from electric driving mode to hybrid driving mode occurs. In order to enhance the riding comfort, two additional wet clutches are mounted in this novel CPSHT and the relevant coordinated control strategy is developed. Firstly, after the description of the mechanical and hydraulic parts of the novel CPSHT, the dynamic plant model including driveline model, engine ripple torque and clutch torque is deduced. Secondly, the mode transition process in the original and current designs are compared and analyzed with the equivalent level diagram and the encountered problems are stated. Thirdly, a coordinated control strategy is designed to determine the target motor torque, clutch torque, engine torque, and the moment of fuel injection based on the second-order sliding mode
Shen, Dengfeng, Guehmann, Clemens, Zhang, Tong
Development of Empirical Asperity Contact Model for Wet Friction Material2019-01-03464/2/2019
A wet clutch couples or decouples gear elements to alter torque paths in an automatic transmission system. During the gear shifting event, the clutch torque is directly transmitted to the output shaft. Hence, clutch torque heavily influences the dynamics of the transmission. In order to evaluate the behavior of the transmission early and efficiently, the development process increasingly relies on high-fidelity transmission system simulations with added complexity. However, a wet clutch continues to be modeled using Coulomb’s friction in a typical shift simulation. Its linear framework does not physically represent non-linear hydrodynamic effects due to the presence of oil layer during clutch engagement. To make up the lack of physics, Coulomb’s clutch model often requires extensive tuning to match actual shift behaviors. Alternatively, a squeeze film based clutch model, coupled with an asperity contact model, can be employed to represent hydrodynamic behaviors and enable the broader
Haria, Hiral, Fujii, Yuji, Pietron, Gregory M., Miyagawa, Masatoshi, Tsuchiya, Takahiro, Nakamura, Shinji, Wendel, Matthew, Miyoshi, Hiroya, Hou, Shiyang, Wang, Pengchuan, Katopodes, Nikolaos
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
Bagadekar, Vijaykumar Shankar, Alavilli, Satya Pavan, Kadhar Maideen, Salim Malik, Rajendran, Ashok Kumar, Radhakrishnan, Padmanaban, Soni, Sandeep
The Influence of Friction Modifiers in Fully Formulated Motorcycle Engine Oils2018-32-002410/30/2018
Globally, emissions legislation placed on motorcycles is becoming ever more stringent [1]. One way of meeting these new regulations is to use friction modifiers (FMs) in the engine oil to reduce frictional losses in the engine. This is, however, complicated by the fact that many motorcycles use a common oil sump for both the engine and a lubricated clutch. It is often the case that if a FM reduces friction in a steel/steel contact it will also reduce friction in a steel/friction material contact. Therefore, it is usually viewed that there will be a necessary compromise between maximizing engine efficiency and maintaining efficient clutch performance. In this paper we examine the effect of a range of organic FMs on commercial fully formulated motorcycle engine oils (MCOs) using benchtop tribotests and full-scale rig tests (SAE #2 clutch test machine). The results show that by careful selection of appropriate FM chemistry it is possible to reduce steel/steel friction whilst maintaining
Gillespie, David, Moody, Gareth, Viadas, Aitziber
Power Transfer Unit Gear Rattle Assessment Using AMESim-ADAMS Co-simulation2018-01-06794/3/2018
The Power Transfer Unit (PTU) provides full time, part-time or on-demand All-Wheel-Drive (AWD) torque distribution for Front-Wheel-Drive (FWD) based AWD systems. FWD has advantage in drivetrain efficiency and fuel economy, while AWD improves traction to have better acceleration and handling. Part-time and on-demand AWD have all the benefits of AWD and the efficiency of FWD. So AWD vehicle option continues to be popular around the world. However, Noise, vibration and Harshness (NVH) error state called PTU rattle has been detected in FWD mode of AWD systems due to torsional excitation. This study is one of the first to be focused on the PTU gear rattle as a NVH error state so far. We developed an AMESim-ADAMS co-simulation model for understanding PTU gear rattle phenomenon through drivetrain torsional responses (i.e. rotational degree of freedom, DOF) in system and PTU rattle assessment through PTU case vibration. The correlated one-Dimensional (1-D) torsional model simulating the
Huang, Hsun-Hsuan, Sun, Wulong, Juang, T. Bin
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
Mahmud, Syeda Faria, Pahlovy, Shahjada A., Ogawa, Makoto
Electro-Hydraulic Shuttle Transmission and Control for Tractors with Non-Electronic Engine2018-01-03904/3/2018
Recently, emerging technological developments in powertrain were mostly accompanied with electronics for efficient and precise control of various powertrain systems like engine, transmission, hydraulics, etc. Agricultural tractors are of no exception to this context. Most of the higher horsepower tractors above 50 HP are equipped with modern transmission systems such as Power-shuttle, Power-shift etc. having their wet clutch transmission and diesel engine controlled by an Electronic Control Unit. This is possible only with an engine that receives and provides electronic signals. Whereas a tractor with mechanical (non-electronic) engine is of predominant use in the Indian farm lands due to their low cost and immediate availability compared to that of an engine equipped with high-end electronics. Hence, there is a demand for low cost drivetrain with improved controls and without engine electronics. This research work depicts on one such development, where an effective power shuttle
Rajagopal, MahendraMohan, M A, Velmurugan
Drag and Cooling Characteristics of Circular Pin-Fin Groove Pattern of a Multi-plate Clutch Pack Using CFD2018-01-03874/3/2018
A numerical analysis of drag torque and cooling characteristics of a Multi-plate clutch pack with a circular pin fin shaped groove pattern is presented in this article. Simulations were performed using Simerics MP® platform to investigate the drag torque and heat transfer under various operating conditions. The performance characteristics of the circular pattern were later compared with various designs from the literature. Some of the groove pattern designs considered have been commonly used in transmission systems and some are from the patent literature. This study compares each design and later proposes the most efficient, that has the least drag and highest heat transfer characteristics.
Yashwanth, Bangalore Lingaraj, Ngo, Dinh, Schroeder, Debera, Hopson, Brian, Wang, De Ming
In-Vehicle Characterization of Wet Clutch Engagement Behaviors in Automatic Transmission Systems2018-01-03954/3/2018
A new generation of a planetary-gear-based automatic transmission system is designed with an increasing number of ratio steps. It requires synchronous operation of one or more wet clutches, to achieve a complex shift event. A missed synchronization results in drive torque disturbance which may be perceived by vehicle occupants as an undesirable shift shock. Accurate knowledge of clutch behaviors in an actual vehicle environment is indispensable for achieving precise clutch controls and reducing shift calibration effort. Wet clutches are routinely evaluated on an industry-standard SAE#2 tester during the clutch design process. While it is a valuable tool for screening relative frictional behaviors, clutch engagement data from a SAE#2 tester do not correlate well with vehicle shift behaviors due to the limited reproducibility of realistic slip, actuator force profiles, and lubrication conditions. Advanced clutch testers with programmable slip and force controller are available for
Haria, Hiral, Pietron, Gregory M., Meyer, Jason, Fujii, Yuji, Wang, Pengchuan, Katopodes, Nikolaos
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
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
Wang, Pengchuan, Katopodes, Nikolaos
Combined Spatter and Immersion Type Oil Cooling System for Multi Disc Wet Clutch Transmission in Tractors2017-28-19767/10/2017
The utility of tractors in India has grown and is growing. Other than in agricultural area, it finds use in non-agricultural and construction/ earthmoving applications like loaders, dozers, power source, etc. The tractors that are subjected to heavy duty cycles are mostly with conventional dry type clutches. These types of dry clutch when operated in heavy application generate large amount of heat within shorter period of time on the surface of friction discs. This increase in disc surface temperature weakens the friction material property & bonding element leading to deterioration and decreasing the life of clutch. This curtails the clutch life extensively and is a big challenge to farmers and tractor users. The frequent clutch failures not only increases the operating cost, but also the servicing of clutches in the tractor fitted with heavy attachments leads to a higher downtime and service cost. To overcome this challenge, an innovative solution in the oil spatter concept has been
Narayana Rao, Suresh Kumar
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
Dolatabadi, Nader, Rahmani, Ramin, Theodossiades, Stephanos, Rahnejat, Homer, Blundell, Guy, Bernard, Guillaume
Traditional and Electronic Solutions to Mitigate Electrified Vehicle Driveline Noises2017-01-17556/5/2017
Hybrid powertrain vehicles inherently create discontinuous sounds during operation. The discontinuous noise created from the electrical motors during transition states are undesirable since they can create tones that do not correlate with the dynamics of the vehicle. The audible level of these motor whines and discontinuous tones can be reduced via common noise abatement techniques or reducing the amount of regeneration braking. One electronic solution which does not affect mass or fuel economy is Masking Sound Enhancement (MSE). MSE is an algorithm that uses the infotainment system to mask the naturally occurring discontinuous hybrid drive unit and driveline tones. MSE enables a variety of benefits, such as more aggressive regenerative braking strategies which yield higher levels of fuel economy and results in a more pleasing interior vehicle powertrain sound. This paper will discuss the techniques and signals used to implement MSE in a hybrid powertrain equipped vehicle. MSE utilizes
Valeri, Frank C., Lagodzinski, James T., Reilly, Scott M., Miller, John P.
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
Alzuwayer, Bashar, Prucka, Robert, Haque, Imtiaz, Venhovens, Paul
Agile and Low-Cost Experimental Evaluation of Fuel Consumption Reduction of a New Electrified Clutch Transmission Virtually Connected to a Vehicle2017-01-10963/28/2017
Automated Manual Transmission (AMT) based on classic electrohydraulic clutch actuation gives high performances and comfort to a recreational vehicle. However, overall power consumption remains high due to the pump efficiency. In addition, the pump is often driven by the vehicle’s engine and thus is continuously working. To address this issue, a new electrified clutch based on electromechanical actuation has been designed and prototyped. In order to evaluate the effective fuel consumption reduction using this new clutch actuator, a low-cost and agile method is presented and used in this paper. Indeed, instead of integrating the clutch actuator in a real vehicle and performing expensive real emission test cycles on a road, this original method proposes to perform accurate semi-virtual emission test cycles. Moreover, the method allows to perform numerous test iterations in a short time. This consists in connecting the prototyped new electric clutch to a virtual vehicle in order to test it
Temporelli, Robin, Micheau, Philippe, Boisvert, Maxime
Development and Challenges of Electrically Selectable One-Way Clutches2017-01-11333/28/2017
This paper discusses new developments in the field of one-way clutches (OWC). These recent developments involve “Selectable OWC (SOWC)” actuating both hydraulically as well as electrically. The primary focus of this paper is a low-current consuming Electrical SOWC (eSOWC) used in hybrid transmission being designed and developed at Ford Motor Company. Other SOWCs currently being utilized across different applications at Ford are also discussed. Clutching devices represent significant cost, weight, size and drag-loss in automatic transmissions. However, implementation of SOWCs offers the potential to reduce transmission cost, size, weight, and spin loss; eSOWCs may also improve shift quality, reduce shift times, improve shift consistency and reduce OWC-related NVH. In Hybrid applications the electric motor(s) and SOWC create a system that is analogous to a manual transmission synchronizer. Similarly, in automatic transmissions SOWC are analogous to pump-solenoid-valve-friction-clutch
Bird, Norman J., Bindra, Raunak, Klaser, Jacob
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
Fujii, Yuji, Wang, Pengchuan, Katopodes, Nikolaos
A Calibration Optimizer Tool for Torque Estimation of K0 Clutch in Hybrid Automatic Transmissions2017-01-06033/28/2017
Software development for automotive application requires several iterations in order to tune parameters and strategy logic to operate accordantly with optimal performance. Thus, in this paper we present an optimizer method and tool used to tune calibration parameters related to torque estimation for a hybrid automatic transmission application. This optimizer aims to minimize the time invested during the software calibration and software development phases that could take significant time in order to cover the different driving conditions under which a hybrid automatic transmission can operate. For this reason, an optimization function based on the Nelder-Mead simplex algorithm using Matlab software helps to find optimized calibration values based on a cost function (square sum error minimization). This work will present a K0 clutch in a hybrid automatic transmission run under several operating conditions, and the method with which the optimizer aids the parameter calibration process in
Cuapio Espino, Vicente, Bichkar, Akshay, Osorio, Joycer D.
Fluid Effects on Shifting Clutch Friction2016-01-220610/17/2016
Good shift quality in automatic transmissions is important for fuel efficiency, driver comfort, and performance. Maintaining this performance over the life of the vehicle is also important. Typically lubricant development focuses on reducing viscosity and friction in order to reduce parasitic losses. In an automatic transmission other factors are also important for good performance, primarily due to the shifting clutches and the torque converter clutch. A high level of friction is desirable for torque capacity and a steady decrease in friction as sliding speed (rpm) decreases is necessary for both good shift feel and good friction system durability over the lifetime of the vehicle. Changes in the friction system over time that result in a lowering of the friction level, particularly at higher sliding speeds, compromise the performance of both types of clutches. In this paper, an experimental shifting clutch durability study demonstrates the impact of changes in friction materials on
Williams, Darryl, Guevremont, Jeffrey, Perry, John
Effect of Fluid Flow through Clutch Material on Torque Fluctuations in Clutches2016-01-234310/17/2016
Improving vehicle fuel efficiency is a key market driver in the automotive industry. Typically lubricant chemists focus on reducing viscosity and friction to reduce parasitic energy losses in order to improve automotive fuel efficiency. However, in a transmission other factors may be more important. If an engine can operate at high torque levels the conversion of chemical energy in the fuel to mechanical energy is dramatically increased. However high torque levels in transmissions may cause NVH to occur. The proper combination of friction material and fluid can be used to address this issue. Friction in clutches is controlled by asperity friction and hydrodynamic friction. Asperity friction can be controlled with friction modifiers in the ATF. Hydrodynamic friction control is more complex because it involves the flow characteristics of friction materials and complex viscosity properties of the fluid. This paper shows how NVH and torque capacity can be controlled by optimizing the flow
Devlin, Mark, Williams, Darryl, Glasgow, Michael, Hux, Karen, Whitworth, Aaron, Cameron, Timothy
Estimation of the Clutch Characteristic Map for an Automated Wet Friction Clutch Transmission2016-01-11134/5/2016
Higher demands on comfort and efficiency require a continuous improvement of the shift process. During the launch and shift process the clutch control is used to get a smooth and efficient behavior. In this short time of acting the shifting behavior can be rated. Many control concepts use a clutch characteristic to calculate the actuator signal based on the clutch torque. Therefore, a high quality of this characteristic is necessary. Because of the dynamic process during clutch engagement the clutch characteristic needs further information to reach a high accuracy for the control algorithm. In this paper an existing clutch torque characteristic is extended to a characteristic map where the clutch torque becomes a function of the current actuator signal of the clutch and the clutch slip. The extension of the torque characteristic describes the slip based dependencies, e.g. the friction coefficient. The model of the characteristic map consists of the multiplication of two separate
Arndt, Thorsten, Tarasow, Alex, Bohn, Christian, Wachsmuth, Guido, Serway, Roland
New Development of a Gas Cavitation Model for Evaluation of Drag Torque Characteristics in Disengaged Wet Clutches2016-01-11374/5/2016
A significant reduction of C02 emission can be achieved by improving the efficiency of transmission of cars. A reduction of drag torque or spin loss of disengaged clutches can improve the efficiency of transmissions. Generally, the drag torque is measured by conducting drag test which needs making samples, manpower, power and wastage of raw materials. In this paper, an analytical model is proposed to predict the drag torque of a disengaged wet clutch at different rotation speeds, clearances, disk sizes and oil temperatures without making any samples and conducting any drag tests. Various assumptions are made from the results of visualization investigations. Visualization results show that the volume of oil existed in between the clutch disk and clutch plate decreases with increasing speed due to centrifugal force. It is also noticed that several visible air bubbles are formed in the oil film at lower speeds and the size of the bubbles increase with increasing speeds. We consider that
Pahlovy, Shahjada A., Mahmud, Syeda F., Kubota, Masamitsu, Ogawa, Makoto, Takakura, Norio
Lubricants Formulation Technology for Fuel Saving Performance in Automatic Transmissions2015-01-20379/1/2015
The use of Automatic Transmission Fluids (ATFs) with lower viscosity and excellent anti-shudder durability for wet clutch system will be effective for improving fuel saving performance in automatic transmissions. In this study, two ATF formulation techniques were examined. The first trial formulation is to improve fatigue life in gear components even if a lower viscosity ATF is used. The second one is to improve anti-shudder durability for wet lock-up clutch system in AT units. As to fatigue life performance, the relation between molecular weight of Viscosity Index Improver (VII) and film formation property in EHL contact regions were experimentally investigated. ATFs containing VIIs with lower molecular weight tend to increasing EHL film thickness, resulting in a longer gear pitting fatigue life. Calcium detergents and ashless friction modifiers in ATFs were found to give a great impact on the anti-shudder performance. The trial ATF containing these additives demonstrated 1.5 times
Yokomizo, Masato, Iwai, Toshiaki, Narita, Keiichi, Kudo, Mitsugu
Investigation on Torque Jump Up and Vibration at High Rotation Speed of a Wet Clutch2015-01-21846/15/2015
Reduction of the drag torque and longevity of the clutch assembly are the most important factors for vehicle transmission improvement. The decreasing trend of the drag torque with speed after its peak is a common characteristic of the clutch assembly. Several theoretical models have been presented by the researchers describing the drag torque characteristics at lower clutch speed. However, very little study has been made on the drag torque behavior at very high clutch speed (6000∼10000+ rpm). The alarming jump of the drag torque at high speed operating condition remains unexplained till date. In this paper, we investigated the possible reasons of torque jump up at high rotation speed and solution to overcome this problem. We presented an analytical correlation of torque jump up with the excessive decrease of local static pressure and assumed that vacuum formation is the possible reason of high speed torque rising and associated vibration. Result shows that when the separator plates are
Mahmud, Syeda, Pahlovy, Shahjada
Optimization of DCT Power-On Upshift Control Strategy Based on PSO Algorithm2015-01-11094/14/2015
This investigation presents a methodology to develop and optimize shift process control strategy to improve shift quality as perceived by drivers during power-on upshift events for Dual Cultch Transmission (DCT) vehicles. As part of the first study, the main factors affecting shift quality during shifting process under typical working conditions are analyzed. And taking the power-on upshift as example, dynamic model of DCT shifting process is build. An Integrated control strategy is proposed for power-on upshift, which during torque phase slipping revolving speed controller is adapted to harmonically control two clutches power switching process, and during Inertial phase engine torque is regulated to synchronize with the value of target gear while holding the oncoming clutch pressure. Oncoming clutch oil pressure gradient in torque phase and engine torque reducing target decrement in inertial phase are chosen as controlled quantity. The proximity between actual and ideal shift process
Lei, Yulong, Liu, Ke, Fu, Yao, Lin, Ge, Song, Bin
Dry Dual Clutch Transmission (DCT) Thermal Model2015-01-11444/14/2015
Dual Clutch Transmissions (DCT) for passenger cars are being developed by OEMs and suppliers. The driving force is the improvement in fuel economy available from manual transmissions together with the comfort of automatic transmissions. A dry clutch system (dDCT) is currently the subject of research, development, and production implementation. One of the key issues in the development of a dDCT is clutch durability. In dry clutches with current linings, above a critical temperature, the friction system starts to suffer permanent damage. In addition, the clutch friction characteristics are a function of the clutch interface temperature. Because a reliable, low-cost temperature sensor is not available for this application, the clutch control engineers rely on a good thermal model to estimate the temperature of the clutches. A thermal model was developed for dry dual clutch transmissions to predict operating temperature of both pressure and center plates during all maneuvers. The model is
Hebbale, Kumaraswamy, Samie, Farzad, Kish, Jonathan
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