Today, the contribution of the transportation sector on greenhouse gases is evident. The fast consumption of fossil fuels and its impact on the environment have given a strong impetus to the development of vehicles with better fuel economy. Hybrid electric vehicles fit into this context with different targets, starting from the reduction of emissions and fuel consumption, but also for performance and comfort enhancement. Lamborghini has recently invested in the development of a hybrid super sport car, due to performance and comfort reasons. Aventador series gearbox is an Independent Shift Rod gearbox with a single clutch and during gear shifts, as all the single clutch gearbox do, it generates a torque gap. To avoid the additional weight of a Dual Clutch Transmission, a 48V Electric Motor has been connected to the wheels, in a P3 configuration, to fill the torque gap, and to habilitate regenerative braking and electric boost functions. This paper discusses the usage of a control-oriented vehicle and powertrain model to analyze the performance of the first Lithium Ion Capacitor-based hybrid V12 by Automobili Lamborghini. The internal combustion engine, the gearbox, the LiC and the vehicle longitudinal dynamics models have been initially validated through the comparison with experimental data from chassis dynamometer testing, in addition to experimental results from specific components’ testing. As shown in the paper, the validated model has then been used to develop control strategies aimed at increasing comfort and performance, but also to expand the hybrid system capabilities by widening the LiC working range, and to study the possibility of implementing CO2 reduction-oriented control functions.

Franceschi, Alessandro, Cavina, Nicolo, Parenti, Riccardo, Reggiani, Maurizio, Corti, Enrico

Dynamics and Control of Gearshifts in Wet-Type Dual Clutch Transmission for BEVs

2020-01-07674/14/2020

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 shift control strategy of the dual clutch transmission is studied, and the method of improving the shift smoothness by the correction of the shift control strategy is proposed.

Lou, Zhenxiong, Duan, Yupeng, Zhang, Yunqing

Two-Speed Transmission Gear Shift Process Analysis and Optimization Using Genetic Algorithm

08-09-01-00011/16/2020

Electric Vehicle (EV) equipped with two-speed transmission has benefit in improving dynamic performance and saving battery consumption. However, during gear shift process, torque interruption and shift impact may lead to a bad shift quality. This work investigates gear shift process in an Automated Manual Transmission (AMT) configuration-based two-speed transmission. First of all, a typical gear shift process is analyzed. Parameters like motor speed, shift force, motor torque change rate, and speed difference between synchronizer and target engage gear are all included to find the relationships with shift duration. Then vehicle jerk is introduced as a criterion to evaluate shift impact. Besides, a comprehensive shift control strategy is developed. While keeping the output torque at wheels unchanged, the shift strategy also improved motor working efficiency after gear shift. Therefore, to determine an optimum shift strategy and achieve a balance among different parameters, Genetic Algorithm (GA) multi-objective optimization method is implemented. Through GA optimization, several solutions are presented and discussed. The final results can well satisfy the requirements of different objectives. This work provides a novel and efficient method for shift strategy development.

Cao, Zhan, Yang, Jiansen, Wang, Xinyu

Automatic Transmissions - Schematic Diagrams

J647_201911 (Current)11/19/2019

The following schematic diagrams reflect various methods of illustrating automotive transmission arrangements. These have been developed to facilitate a clear understanding of the functional interrelations of the gearing, clutches, hydrodynamic drive unit, and other transmission components. Two variations of transmission diagrams are used: in neutral (clutches not applied), and in gear. For illustrative purposes, some typical transmissions are shown.

Automatic Transmission and Transaxle Committee

Modelling and Control of a Novel Clutchless Multiple-Speed Transmission for Electric Vehicles

2019-24-00639/9/2019

Conventional electric vehicles adopt either single-speed transmissions or direct drive architecture in order to reduce cost, losses and mass. However, the integration of optimized multiple-speed transmissions is considered as a feasible method to enhance EVs performances, (i.e. top speed, acceleration and grade climbing), improving powertrain efficiency, saving battery energy and reducing customer costs. Perfectly in line with these objectives, this paper presents a patented fully integrated electric traction system, as scalable solution for electrifying light duty passenger and commercial vehicles (1.5-4.2 tons), with a focus on minibuses (<20 seats). The adoption of high-speed motor coupled to multiple-speed transmission offers the possibility of a relevant efficiency improvement, a 50% volume reduction with respect to a traditional transmission, superior output torque and power density. The proposed clutchless four-speed transmission is specifically conceived and designed to have the good matching with the traction electric motor. Indeed, clutches and synchronizers are not required thanks to the small inertia of the traction motor and its fast regulation in both torque and speed mode (torque modulation process). Therefore, an advanced shifting control system/strategy has been developed to reduce the time shifting, linked to the degree of jerk and the power interruption, guaranteeing the coordination of all the gear-shifting actuators despite the randomness of the gear shifting process. After the description of the system layout, the paper gives an insight of the plant dynamic model and its equations. The controller architecture along with its strategies are also presented. The effectiveness of the proposed solution is proven through an extensive set of simulations carried out for a vehicle running on a real driving cycle.

Malafronte, Ludovica, Grandone, Mauro, Lega, Alberto, Pennese, Michele, Pianese, Cesare

WHAT WE'RE DRIVING

19AUTP09_089/1/2019

As the sporting player in Volvo's C-segment sedan lineup, this all-wheel drive, turbocharged-and-supercharged R-Design S60 faces benchmark competition in the BMW 3-Series, Audi A4 and Mercedes-Benz C-Class. In pure performance, the stylish Swede stacks up nicely against the Germans: Its 316 hp (236 kW) pushes the 3,900 lb (1769 kg) car plus my 200-lb (91 kg) of dead weight from a standstill to 60 mph (97 km/h) in 5.5 s, according to my stopwatch. Dynamically, the S60 T6 (not my choice of nomenclature, as it's a 4-cyl., not a six) feels solid and secure, if not exceptionally nimble, when pushed hard in the corners. But where the S60 R-Design clearly beats the others is inside, the area where Volvo shows its taillamps to the other premium brands. The S60's cabin is a beautifully integrated blend of rich materials and tasteful accents - brushed aluminum of the lower IP contrasting with deep ebony, offset by delightful-to-touch control knobs. The front seats are both handsome and comfortable. Rear-seat legroom is excellent, as my 37-in. (940-mm) inseam can attest.

Dual Clutch Transmission Vibrations during Gear Shift: A Simulation-Based Approach for Clunking Noise Assessment

2019-01-15536/5/2019

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

Effect of Maneuvering and Gust Loads on the Two-Speed Shift Dynamics of a Helicopter Equipped with a Dual Clutch Transmission

F-0075-2019-14672

5/13/2019

This paper explores the effects of maneuvering and gust loads on the drive system and flight dynamic response of a single main rotor helicopter equipped with a two speed dual clutch transmission. The authors demonstrate that performing upshifts during certain maneuvers can significantly reduce the transmitted clutch frictional torques and the resulting clutch pack temperature rise during gear changes. For example, compared with an upshift in level flight, performing a 8° pitch-up maneuver reduced peak clutch frictional power dissipation by 63% (from 455 Hp down to 169 Hp) and reduced total upshift time by 37% (from 5 seconds down to 3 seconds). This results in an 83% reduction in total heat energy dissipated by the clutch during the upshift. Since the design of the clutch pack mass is directly proportional to the heat dissipation requirements, this new (Maneuver Assisted Shifting) MAS technique could enable significant weight savings and clutch wear reduction in helicopter two-speed transmissions.

DeSmidt, Hans, Smith, Edward, Su, Xiaowen, Bill, Robert

Modeling and Validation of a Transmission E-Pump for Application in Hybrid Vehicles

2019-01-03494/2/2019

The Electric Pump (E-Pump) is a critical component in the hybrid transmission system. The E-Pump provides flow to maintain a stable line pressure when the engine is in an off state. The main applications of the E-Pump are Park Pawl engagement and disengagement, engine start-stop operation and shadow shifting. A Systems Engineering Approach was followed to develop a medium fidelity plant model for the E-Pump. The developed model was initially tested and validated in the Model in-the loop (MIL) environment. After initial validation, the model was integrated into the overall vehicle model which was then tested on the Software in-the loop (SIL) and Hardware in-the loop (HIL) environments. The model was validated across different platforms and several operating conditions. The basic applications of the E-Pump such as park pawl actuation, engine starting and shadow shifting were validated. The model was later validated using the data, which was acquired on a prototype vehicle run on a dynamometer. The goal was to develop a common model, which could be used across different simulation platforms such as MIL, SIL and HIL. Development of the E-Pump model enabled early testing of critical requirements related to basic functionality of the system which otherwise would have be difficult to test. This in turn accelerated the software development process, which resulted in developing a mature and robust software even before the actual hardware was available. This paper describes the modeling and the verification and validation methods that was used for implementing the E-pump model across several platforms.

Kannan, Kaushik, Veeramurthy, Gangarjun, Yamazaki, Mark

Theoretical and Experimental Investigation on Power Loss of Vehicle Transmission Synchronizers with Spray Lubrication

2019-01-00281/15/2019

Besides optimal engine systems, high-efficiency vehicle transmissions are generally also required to improve fuel economy in automotive applications. For the energy loss analysis in transmissions, most research focused on the major mechanical components, such as gears, bearings and seals, while the other mechanical losses, like synchronizer losses, were usually not considered. With increasing number of synchronizers in modern transmissions, a recent study indicates that the power loss analysis of synchronizers should also be developed and appended for a more accurate investigation on overall power losses in transmissions. The function of synchronizer is to equalize the different rotational speeds of shafts and gear wheels by frictional torques, for which the synchronizer must be cooled and lubricated in order to enhance the service life. With the supplement of lubricants, fluid friction is generated due to the differential speed, when the synchronizer is in neutral position. This fluid friction can be principally regarded as load-independent synchronizer power loss. In this paper, fluid states and fluid dynamics in synchronizers with spray lubrication are analyzed analogously to multiple-plate clutches. Based on that, synchronizer power losses are modelled physically. With the physical model, possible influential factors on synchronizer power losses are determined. Together with consideration of the current test bench, an experimental design is developed regarding individual power loss testing on the system test bench. Through investigating the test results, the synchronizer power loss behavior is comprehensively analyzed and the physical model is optimized by means of parameter sensitivity analysis and optimization methods. The model is validated by the experimental data from literature.

Liu, Zhihong, Shen, Ye, Rinderknecht, Stephan

Prediction of Oil Flow inside Tractor Transmission for Splash Type Lubrication

2019-26-00821/9/2019

This study introduces a method to examine the flow path of the lubricant inside a transmission housing of a tractor. A typical gearbox has several loads bearing elements which are in relative sliding motion to each other which causes heat to be released. The major sources of friction as well as heat are the meshing teeth between gears (sun/planet, planet/ring & power/range drive gear), thrust washers, thrust bearings and needle roller bearings. The churning of oil performs the vital function of both lubricating these sliding interfaces and cooling these sources of heat, thereby preventing failure of the gearbox. In this paper, we have applied VOF multiphase flow model and sliding meshing to simulate the fluid flow during splashed lubrication within a mating gear box. Lubrication oil dynamics and oil surface interaction with the air is modeled using VOF multiphase approach. The gear motion is imparted through sliding mesh technique, it automatically reconfigures the mesh for the space in accordance with the rotation of physical objects, which divides the space around the gears, centering on the axis of rotation to simulate the motion of the gears. The method captures the effect of rotation of the gears and shaft in a transmission. The entire transmission unit is considered for the analysis to study the cumulative effect of the motion of all the gears on the oil flow against the general practice of studying the local effect. After solving for 3 seconds in high speed forward boundary condition, volume fraction of oil at the at the oil holes that carry the oil to the bush & the gear interface, reveled two locations one on the fourth gear of drive shaft and another at the first gear of the driven shaft. By volume the quantity was very less when compared to the other gear. The supply of lubricant to the bush & gear interface depends on the location of oil supply hole on the gears and shafts. After running the transmission for 150 hours on test bed scoring marks were observed between the gears inner diameter & bush outer diameter due the relative motion between the inner surfaces. This failure was attributed to scarcity & delay of oil to bush. Estimating the lubrication in advance during the design step helps reduce the development period & expenses for prototypes. This paper explains how the CFD simulation can we used to understand the lubrication flow inside the tractor transmission.

Santra, Tanmay Sushant, Raju, Kumar, Deshmukh, Rahul, Gopinathan, Nagarajan, Paradarami, Udaya, Agrawal, Ayush

The Influence of Friction Modifiers in Fully Formulated Motorcycle Engine Oils

2018-32-002410/30/2018

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 clutch performance. To obtain a deeper understanding of the effect of FM chemical structure on the clutch friction performance the friction-speed (μ-v) behaviour of a commercial MCO formulation is investigated. It is found, in agreement with previous studies, that a lower amount of branching in the alkyl tail of an organic FM corresponds to a positive correlation between friction and speed of the type usually desired in an automatic transmission fluid (ATF). This contrasts with the μ-v behaviour of a commercial MCO intended for use in motorcycles with a wet clutch, which shows almost no correlation between friction and speed. This insight could be used to help rational design of new OFMs for motorcycle oils.

Gillespie, David, Moody, Gareth, Viadas, Aitziber

Conceptual Design Challenges and Solutions in Power Shuttle Transmission Development for Legacy Tractors

2018-01-03944/3/2018

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

A Development of Fuel Saving Driving Technique for Parallel HEV

2018-01-10064/3/2018

This paper examines the effect of pulse-and-glide (PnG) driving strategies on the fuel efficiency when applied on parallel HEVs. Several PnG strategies are proposed, and these include the electrical, mechanical, and combined PnG strategies. The electrical PnG strategy denotes the hybrid powertrain control tactics in which the battery is charged or discharged according to the power demanded while maintaining the constant vehicle speed. On the other hand, the mechanical PnG strategy denotes the powertrain control tactics in which the vehicle accelerates or decelerates according to the power load while minimizing the battery usage. The combined PnG strategy involves both electrical and mechanical strategies to find a balanced point in between them. Here, a tradeoff relationship between the fuel efficiency and the vehicle drivability related to the tracking performance of the desired target speed is revealed. In the assessment of the feasibility of applying each of the formerly mentioned hybrid driving strategies, the causes of driveline heat loss are recorded and analyzed by their types. These include the engine heat loss, engine friction loss, motor loss, and the resistance loss. The motor loss includes all of the electrical energy loss induced in the powertrain electronics, and the resistance loss includes the loads acting on the vehicle such as the aerodynamic drag and rolling resistance. These factors are quantitatively analyzed for different driving strategies along with the related fuel efficiency in an integrated manner. The experimental validation is conducted using a real HEV equipped with a gasoline spark-ignition engine, transmission-mounted electric drive, and a 6-speed dual clutch transmission.

Eo, Jeong Soo, Kim, Sung Jae, Oh, Jiwon, Chung, Yeon Kwang, Chang, Young Joon

A Review of the State of the Art of Electric Traction Motors Cooling Techniques

2018-01-0057

4/3/2018

This paper provides a review on state-of-art modern cooling systems employed for thermal cooling of electric motors for vehicle applications. In recent years, the pursue of a more sustainable and ecofriendly mobility has pushed the research towards the development of electric vehicle powertrain systems. Besides the evident advantages of the adoption of electric traction systems in terms of pollution and efficiency, the need of an effective cooling system for the electric machine components gained more and more importance in order to maintain high efficiency and ensure high durability. In fact, it is known that high temperatures can be harmful for the electric motor: besides the evident damages for mechanical parts, the influence on the permanent magnet properties is not negligible [1] [2]. In this fast-evolving environment, different solutions for the thermal problem have been researched and adopted, each one with its own pros and cons. Those who face the development of a PM machine can found plenty of these solutions in literature; so, the purpose of this paper is to draw a first qualitative comparison among the most important mechanisms available to extract heat from the electric machine and to guide the reader to an efficient and effective solution. Various methodologies for heat extraction are here described: resilient thermal pads for a conductive cooling; forced air and liquid loops, spray cooling and hollow rotor shaft for gases/fluids convective cooling methods. Finally, it is provided a table for a qualitative comparison among the various cases.

Carriero, Alberto, Locatelli, Matteo, Ramakrishnan, Kesavan, Mastinu, Gianpiero, Gobbi, Massimiliano