Browse Topic: Manual transmissions

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Engine-in-the-Loop Analysis of the Influence of Manual Gearshift Duration on Vehicle Consumption and Emissions15-16-01-00039/27/2022
Abstract The tightening of emission standards and homologation rules lead car manufacturers to rely on simulation testing in early development phases. Coupling an engine to a testbench controlled by a real-time simulation environment allows flexible, reliable, and reproducible testing for consumption and emission studies. However, interest in this method referred to as engine-in-the-loop (EiL) is relatively recent and few details can be found regarding the simulation environment. Following previous work, this study details a driver model based on the PI structure and augmented with preview and anti-windup. The focus is set on a conventional powertrain with a manual transmission for which the driver must also manage the clutch pedal during gearshift and take-off phases. Extended analysis of vehicle tests allows defining the driver’s behavior during these phases for different profiles. The driver model is then tested in the EiL environment and the impact of the gearshift profile on fuel consumption and pollutant emissions can be assessed. Besides the slight increase in fuel consumption, results show that increasing the gearshift duration degrades the regulation of the richness by the ECU, thus increasing CO engine-out emissions as well as decreasing NOx emissions. Finally, results suggest that a longer gearshift also affects the catalyst efficiency, which results in higher NOx tailpipe emissions.
Gilormini, Thomas, Chessé, Pascal, Tauzia, Xavier, Colin, Hervé
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
Main Features of Forming the Transmission of an Active Multi-Link Road Train2020-01-04274/14/2020
The development of the economy and the associated growth in trade both within the country and international transport, the associated construction and development of transport routes using elements of intelligent transport systems constantly require increasing the efficiency of trunk transportation. In addition, the development of new economic regions with an undeveloped road network is impossible without high-capacity motor vehicles and cross-country ability. To achieve these goals, the creation of active road trains, including multi-link ones, based on non-traditional technical solutions, is required. The idea of using multi-link trains in the system of intercity and international transportation is not new. However, at the present stage of development of automotive technology requires rethinking and use of new achievements of science and technology. At present, the process of changing the design of land vehicles, qualitatively changing their structure and composition of the main power devices based on the integration of electronic, electrical, hydraulic, pneumatic and mechanical elements and significantly increasing the role of electronics and control systems, i.e. widespread introduction of mechatronic systems and modules in the design of a road train. The article describes some aspects of constructing the transmission of active road trains based on the mechatronic modular principle. Materials of the article are based on the results of theoretical and experimental studies conducted by the authors and with their participation. In this article, the term “mechatronics” is understood as a synthesis of electromechanics and microelectronics, combined by a common control and optimized according to system-wide criteria.
Belousov, Boris, Haritonchik, Sergey, Keller, Andrei, Bakhmutov, Sergey, Berdnikov, Alexey, Alyukov, Sergei, Alyukov, Alexander
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
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 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 Algorithm08-09-01-00011/16/2020
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
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 box, the automated half of the equation - mechatronic actuators to engage the clutches and shift the gears - was beyond their ken. Tremec filled that need in 2012 by purchasing Hoerbiger Drivetrain Mechatronics, a Belgium-based supplier of electronic dual-clutch actuators with a customer list including AMG-Mercedes, Ferrari and McLaren.
Sherman, Don
Performance Analysis of an Automated Manual Transmission Controller for Two-Wheeler2019-28-012510/11/2019
This research paper presents controller development and its performance analysis for two wheeler. The comparison for different performance parameters is carried out with and without automated manual transmission (AMT) controller. The AMT considered in this case, includes a conventional manual transmission gear-box with conventional clutch pedal. It is equipped with clutch actuation with the help of linear actuator and the gear shifting using servo motor. The upshift and downshifting of the gears and the clutch actuation is done through the decisions of controller. The results generated during the engine dynamometer test are used as input creating two wheeler vehicle model using AVL cruise software. This vehicle model is used to predict vehicle performance. The vehicle performance results are validated with chassis dynamometer test data. The vehicle model is modified for generation of gear shifting plot. Also Gear shift program (GSP) is generated using the GSP generation module of AVL cruise software. The two criteria used for GSP generation are fuel economy and vehicle acceleration performance. The simulation results include generation of gear shifting graph which covers range from 0-120 kmph. The hysteresis zones are established during up shift and downshift, based on actuator and sensor limitations. The automated manual transmission controller algorithm has used the input of two parameters which are vehicle speed and throttle position. The simulation shows 4% reduction with generated gear shift plot.
Patil, Saurabh Sunil, Wani, Kiran Pralhad
Fuel Efficiency Improvement in Automatic Transmissions by Lockup Slip Methodology2019-28-002910/11/2019
Increasing of automatic transmissions in passenger cars is based on pleasure of driving, smooth acceleration and easy operation makes the customer satisfaction. Challenges beyond 2020 is BS VI emission norms in India - a very tough goals on CO2& NOx reduction in Gasoline & Diesel vehicles. But its setback in lower fuel economy. To support & enhance fuel economy in Automatic transmissions as part of drivetrain technologies, this article discusses about the power losses in torque converters and experiments on the actual Automatic transmission (AT) vehicle on-road to understand the real city driving behavior in the aspects of gear utilization & gas pedal utilization throughout the entire traffic conditions. With that data research, slip area and slipping conditions is determined & clutch slip control is enabled at area in torque converter by ensuring that NVH parameters are not affected. The addition of the Lock-up Slip system add value in terms of “Joy of Driving” by providing a 2-3% improvement in fuel economy over the previous one.
Sukumar, Arun
New-generation Nissan Versa breaks for higher ground19AUTP10_1410/1/2019
Subcompact cars hardly are spotlight-grabbers at the moment, but Nissan's nonetheless delivered up an all-new 2020 Versa that notches higher fuel economy, quicker acceleration, tighter S-curve poise and a quieter cabin compared to the outgoing Versa. “Nissan's third-generation Versa is well-balanced in terms of performance, handling, and ride comfort,” Jose Romo, the car's marketability engineer, told Automotive Engineering during a recent media ride-and-drive program in Nashville, Tenn.
Buchholz, Kami
WHAT WE'RE DRIVING19AUTP10_0710/1/2019
What first impresses about the GT is how easy it is to drive. Ingress is a little tricky over the wide sill, but once situated in the comfy driver's seat you use a strap to position the foot controls to your liking in a very cramped pedal box, and you have a few degrees of seatback angle to play with. The 3.5-L EcoBoost twin-turbo-charged V6 erupts to life from what feels like just behind your right earlobe, but settles quickly in a buzzing idle. Like many competition-focused machines, the V6 has a lightened-crank eagerness about it, but the “automatic” gearbox prevents any uneasiness about getting underway. Thanks to the rear-wheel-drive GT's low and centered mass, the engine can mutter away at low rpm while easily bringing the GT up to traffic speeds.
Modelling and Control of a Novel Clutchless Multiple-Speed Transmission for Electric Vehicles2019-24-00639/9/2019
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
Engineering the 2020 CHEVROLET CORVETTE19AUTP09_019/1/2019
The eighth-gen (C8) Corvette is a creative mix of novel and traditional technical solutions unleashed at a shockingly low base price. Two days before the 50th anniversary of astronaut Neil Armstrong's leap for mankind and 10 years after General Motors emerged from bankruptcy, the camouflage was finally ripped from the eighth-generation (C8) 2020 Chevrolet Corvette. As widely anticipated, C8 now flaunts a mid-engine layout that ostensibly puts it on equal terms with the world's most venerated supercars. After six decades of experimentation and concept-car teasing, GM acknowledged that the new Stingray will enter production before year's end. The truly shocking announcement is a base price of $59,995 including destination, only $3,000 more than today's front-engine C7. Along with moving the cockpit forward 16.5 inches (419 mm) to facilitate shifting the engine rearward, the new Corvette is an innovative mix of novel and traditional engineering solutions.
Sherman, Don
WHAT WE'RE DRIVING19AUTP09_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.
Experimental Investigation on Gear Rattle Noise Reduction in Passenger Car2019-01-15616/5/2019
Gear rattle noise reduction inside the passenger cabin is one of the major challenges for customer comfort enhancement. Therefore, it becomes a prime target during transmission design and development. Gear rattle is generated due to meshing teeth collision of free gears, which is caused due to torsional vibration of engine transferred through clutch. Vibrations are generated due to free gears teeth impact and are transferred to shaft, bearings and transmission housing. The sound absorption and structural vibration of transmission housing was optimized by changing the geometrical features of the transmission housing that affects radiated noise. Experimental approach for gear rattle noise reduction through transmission housing modification is described in this paper. Moreover, CAE method is also incorporated with the experiments for optimization of future vehicle transmission system designs.
Khare, Devendra Kumar, Vaishya, Abhishek Lakhanlal, Pujara, Archan Sunibhai, Krishna, Radhe, Satpathy, Kingshuk, Choudhary, Ved Prakash, Pandey, Anant
Investigation on Cyclic Noise in Vehicle Creeping during Stop-Go Traffic Conditions2019-01-15576/5/2019
Now-a-days, customers are turning more sensitive towards vehicle NVH performance. In order to enhance customer NVH comfort, a specific noise phenomenon was investigated during product development. While testing stop-go traffic conditions, cyclic noise was observed in the 1st gear with the vehicle creeping. The noise was similar to a gear rattling noise. It was perceived unpleasant due to low background noise and wide frequency range of cyclic noise. This paper explains the root cause of this cyclic noise through various drivetrain experiments and also elaborates the experimental analysis approach in order to arrive to the solution in gear and clutch design for cyclic noise elimination.
Vaishya, Abhishek Lakhanlal, Pujara, Archan Sunibhai, Khare, Devendra Kumar, Satpathy, Kingshuk
Jeep revives its pickup mojo with 2020 Gladiator19AUTP05_155/1/2019
Get ready for the fractionalization of the U.S.'s raucous pickup-truck market. Launching what's surely one of the year's most-anticipated and potentially significant new models, Jeep engineers and planners insist they went out of their way to ensure the 2020 Gladiator was developed as a genuine pickup and not “a Wrangler with a bed.” But everyone knows Jeep would've been crazy to stray too far from the radiant demand for the new JL-generation Wrangler, so excuse us if the Gladiator does, well, at least look like just that: a 4-door Wrangler Unlimited-with a bed.
Visnic, Bill
Acceleration Testing of 2000 Van Hool 45 Foot Motor Coach2019-01-04314/2/2019
The time/distance relationship for a motor coach accelerating from a stop is often needed to accurately assess the events leading up to a collision. Several series of tests were conducted to document the low speed acceleration performance of a 45 foot long 2000 Van Hool motor coach equipped with a Cummins ISM engine and an Allison B500 6-speed automatic transmission. These tests included three load configurations and two different acceleration rates, normal and rapid. Data were gathered with a Racelogic VBOX IIIi.
Grimes, Wesley, Balasa, Jonathan, Wilcoxson, Greg
Planetary Power Split Device for Hybrid Vehicle Powertrain2019-01-03704/2/2019
This work looks into the development of power-split planetary gear set for hybrid vehicle. The aim is to research possible solution of hybrid powertrain integrating DHT (Dedicated Hybrid Transmission), which will comply with demands of compact cars, where simplicity and low price is a primary focus. On the other hand, this solution must offer full-hybrid capability. The search of new solution is focused on the usage of one electric motor in combination with internal combustion engine, the planetary gear set (PGS) and stepped transmission. For low forward speeds and reverse the electric drive can be used. The low forward speed can be ensured also by combination of electric motor and ICE, the medium speed range will be covered by powersplit or combination/addition of power of ICE and electric motor, for highway usage the direct drive from ICE via stepped transmission is envisaged. Most of the functional modes allow also the electric energy recuperation. The paper will present the overview of existing solutions; the literature survey will be dedicated for designs with single electric motor mainly. Further will be included the description of newly proposed mechanism, the shift table and full description of all functional modes. For demonstration and simulation purpose was chosen 1.0 L spark ignition engine in combination with 48 V electric motor - the results will be included in the paper. It was decided to build a plastic demonstrator of the newly invented DHT for the functional check.
Kanera, Jaroslav, Achtenova, Gabriela, Kruta, Michal
Modeling of the Automatic Power Distribution System among the Traction Motors of the Driving Wheels of a Multi-Axle Vehicle2019-01-09144/2/2019
Dynamics of acceleration, mobility, fuel efficiency of wheeled vehicles are largely determined by the drive circuit to the driving wheels and bridges, as well as devices used in drive link nodes to distribute power among the driving wheels. This is especially important for multi-axle wheeled vehicles. In this paper, the object of the study is a multiaxial wheeled vehicle with an electric transmission consisting of an internal combustion engine with a power of 720 kW, one common generator and twelve traction motors mounted directly on the driving wheels. In connection with the change in load on the driving wheels due to the variability of soil properties, driving conditions (acceleration, braking, uniform motion), terrain topography, it is necessary to provide external regulation of electric machines working in the transmission of the vehicle. The aims of the work are: 1) the study of currents and voltages in traction motors while changing the properties of the ground during the movement; 2) modeling of the automatic system providing full loading of the internal combustion engine and optimal distribution of power among the driving wheels with full fuel supply; 3) simulation of an automatic control system for traction motors, which provides the operation of the internal combustion engine with an economical characteristic for partial fuel supply and during acceleration. As a result of the study, the model of the automatic power distribution system among traction motors of the driving wheels of a multi-axle vehicle was developed, which made it possible to provide more efficient operation of the multi-axis vehicle.
Kondakov, Sergei, Pavlovskaya, Olga, Aliukov, Sergei, Smirnov, Vladimir
Acceleration Testing of 2011 MCI J4500 45 foot Motor Coach2019-01-04094/2/2019
The time/distance relationship for a motor coach accelerating from a stop is often needed to accurately assess the events leading up to a collision. Several series of tests were conducted to document the low speed acceleration performance of a 45-foot long 2011 MCI J4500 motor coach equipped with a Detroit Diesel Series 60 engine and a ZF AS Tronic 12-speed automatic transmission. These tests included three load configurations and two different acceleration rates, normal and rapid. Data were gathered with a Racelogic VBOX IIIi.
Grimes, Wesley, Wilcoxson, Greg, Balasa, Jonathan
CVT, Promising Solutions for Electrification2019-01-03594/2/2019
A single speed transmission for electric vehicles (EV) puts specific requirements on the electric motor and battery to enable the full characteristics as offered by the internal combustion engine such as driving large distances at higher speed or towing a trailer. EV developers are facing several challenges in extending driving range, reducing recharge times and finding a performance and efficiency compromise between low and high-speed conditions. This study proposes a combination of a dedicated electric machine and a Continuously Variable Transmission (CVT) that offers a chance to overcome these challenges. The result is an efficient and cost effective solution where the surplus cost of the CVT is recovered within the powertrain by lowering cost of the electric components, cooling system and battery. A CVT reduces the maximum torque and speed requirement of the electric machine which enables a reduced size and cost of the active parts. The combination of a downsized electric machine and a pushbelt CVT can deliver the good performance that consumers expect from their EV. This paper combines the results of research into various topics to support these statements. A simulation based comparative study of various EV powertrain configurations shows that with respect to the single speed EV, efficiency benefits around 13% on WLTC are possible. A cost study based on the bill of materials furthermore concludes that a 6% cost benefit is achievable.
Van der Sluis, Francis, Romers, Luc, Van Spijk, Gert-Jan, Hupkes, Ingmar
Optimization of the Process of Acceleration of a Vehicle Taking into Account the Regimes of Operation of Its Engine2019-01-07764/2/2019
Currently, in order to effectively use the engine's energy resources and implement the required indicators of the traction, speed and fuel-economic properties of a vehicle, designers and manufacturers are trying to realize some certain properties to the transmission design that will ensure the most complete coordination of their joint work. However, even the optimal constructive solution cannot be universal, i.e. what is good for some operating conditions is not effective for other conditions. Therefore, today it is economically expedient to create vehicles intended for a certain, relatively narrow range of operating conditions. A wide range of modern continuously variable transmissions (CVT), as well as automatic control systems make it possible to radically change the approach to the design of vehicle transmissions. It remains only to determine the algorithms for changing the gear ratio of the CVT. The technique of a choice of optimum transfer numbers of CVT of a car in view of modes of movement and work of its engine is offered. The results of calculation of the traction-dynamic and fuel-economic parameters of a car with CVT, the gear ratios of which change during the movement in accordance with the proposed procedure, in comparison with the actual prototype, confirmed the accepted optimization hypothesis and gave all grounds for recommending the application of this technique to practice when choosing the gear ratios of continuously variable transmission, depending on the mode of movement of vehicle and regimes of operation of its engine.
Ulanov, Alexander, Aliukov, Sergei
A Generalized Component Efficiency and Input-Data Generation Model for Creating Fleet-Representative Vehicle Simulation Cases in VECTO2019-01-12804/2/2019
The Vehicle Energy Consumption calculation Tool (VECTO) is used for the official calculation and reporting of CO2 emissions of HDVs in Europe. It uses certified input data in the form of energy or torque loss maps of driveline components and engine fuel consumption maps. Such data are proprietary and are not disclosed. Any further analysis of the fleet performance and CO2 emissions evolution using VECTO would require generic inputs or reconstructing realistic component input data. The current study attempts to address this issue by developing a process that would create VECTO input files based as much as possible on publicly available data. The core of the process is a series of models that calculate the vehicle component efficiency maps and produce the necessary VECTO input data. The process was applied to generate vehicle input files for rigid trucks and tractor-trailers of HDV Classes 4, 5, 9 and 10. Subsequently, evaluating the accuracy of the process, the simulation results were compared with reference VECTO results supplied by various vehicle manufacturers. The results showed that the difference between simulated and reference CO2 emissions was on average -0.6% in the Long Haul cycle and 1% in the Regional Delivery. Such a process could be a powerful tool for calculating HDV CO2 emissions for development and analysis purposes, e.g. for new vehicle prototypes or multistage vehicles, and for creating VECTO equivalent models that can be used to assess alternative operating conditions and mission profiles of existing vehicle models. The methodology was applied for creating input of various components in the US tool for HDV certification, GEM, for generic sample-vehicle models available.
Zacharof, Nikiforos, Tansini, Alessandro, Prado Rujas, Iker, Grigoratos, Theodoros, Fontaras, Georgios
WHAT WE'RE DRIVING19AUTP04_094/1/2019
Toyota pickups fitted with gonzo oversize tires, long-travel suspensions and M1 Abrams-quality skid plates have been part of the U.S. off-roading scene since before “Ironman Ivan” Stewart won the Baja 1000 in 1993. His victory ride was developed by TRD, the automaker's U.S. race-engineering group, whose work is manifest in 2019 TRD versions of Tundra, Tacoma and 4Runner production models. As with the off-road-oriented pickups from other OEMs, the Tundra TRD Pro delivers big fun on the rocks. But it demands some compromise as a daily driver, particularly in ride quality, unless your commute is in Colorado's San Juan mountains.
Automotive Gear Lubricant Viscosity ClassificationJ306_201902 (Current)2/6/2019
This SAE Standard defines the limits for a classification of automotive gear lubricants in rheological terms only. Other lubricant characteristics are not considered.
Fuels and Lubricants TC 3 Driveline and Chassis Lubrication
Gearset Synchronization Modeling of a Heavy Commercial Vehicle Transmission and Correlation with Objective Measurements of Gear Shift Quality2019-01-00311/15/2019
For manual transmissions, including the automated types, reduced shifting effort and easy of gear set engagements in a short period of time without rattles and shakes are major requirements for the shift quality evaluations. Performance of the synchronizer mechanisms depends highly on the design, material and arrangement of the transmission synchronization components; thus, the synchronization process is a mechanical and tribological process which is influenced by numerous design parameters of the synchronizers, constraints and properties of the lubricated contacts. In this study, a detailed multi-body-dynamics model for a HCV (Heavy Commercial Vehicle) transmission gearset is presented; various synchronization simulations are performed and the results are compared with the objective shift quality measurements. The developed model yields total synchronization and engagement time based on the applied gear shifting effort. The translational and rotational movements are calculated using the force and moment balance in each stage of the synchronization process solving the governing differential equations numerically. Synchronizer mechanisms are frictional lock-up mechanisms that the synchronization process needs to be considered and evaluated step by step due to the transient nature of lubrication regimes from hydrodynamic to boundary as a result of changing lubricant film thickness, oil viscosity and kinetic coefficient of friction. Besides, the transmission shifting system has complex linkages and detents that is included in the model because of their significant influence on the shift quality. The developed gear set synchronization model was validated using objective GSQA (Gear Shift Quality) measurements obtained in real heavy duty commercial vehicle field tests and various shifting scenarios were simulated. The effects of principal synchronizer design parameters and level of applied force on the shift quality characteristics were discussed in detail.
Özpınar, İlker, Akalin, Ozgen
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
Development of an Assessment Methodology to Measure Effects of Geometrical Clearance of Bowden Type Shifting Cable on Gearshift Quality in Passenger Car2019-26-03411/9/2019
In Indian passenger vehicle Industry, customer’s expectations are becoming more challenging day by day. Gearshift feeling has become most demanding and considered as one of the major area of focus during transmission development. Transmission shifting system helps driver to interface with the vehicle drivetrain along-with other systems. It primarily consists of two systems i.e. Peripheral system and Shift system inside the transmission. Peripheral system includes Gear Shift Lever with knob and shift Cable Assembly. Shift system inside the transmission includes Shift Tower Assembly, Shift Forks and Synchronizer Rings etc. Both the systems play an important role in defining the overall gear shift feeling. Any undesired friction in either of these systems deteriorates gearshift feeling which can cause discomfort to driver while engaging or disengaging the gears. Current paper explains the work done to understand the effect of geometrical clearance of Bowden type shifting cable on gear shifting quality and development of methodology for objective evaluation of gear shifting feeling.
Singh, Paramjeet, Kumar, Krishan, Aneja, Saurabh
Development of Hose and Pipe Assembly for Automatic Transmission Cooling System2019-26-03271/9/2019
Rubber hose and metallic pipe with crimped joints are extensively used in steering system assembly, transmission oil cooler system, brake system etc. to carry hydraulic fluid or lubricants from one place to another. The pipe and rubber hose assembly provides necessary flexibility for complex routing on the vehicle level. Design of hose and pipe assembly for this application are different due to difference in operating pressure and temperature requirement for vehicle application. This paper defines the criteria for design and validation of hose & pipe assembly used to connect automatic transmission with the cooler. Crimped joints are validated for their separation force, leakages, ability to withstand pressure pulsations, burst test etc. Parameters which influence the hose & pipe assembly durability are pipe end flaring dimensions, type of crimping, reinforcement type, its size, material and pattern, rubber material properties, crimping force, effective crimping diameter etc. Minor variations in these design parameters can influence the durability of the assembly. Several trials were carried out to arrive at an optimum design of the hose and pipe assembly for automatic transmission cooling system during development phase. This paper provides guidelines developed based on test results for hose & pipe assembly development. Sensitivity of parameters such as crimping pressure, pipe flaring design, metal cap thickness, effective crimping diameter, crimping type, reinforcement size on durability of hose & pipe assembly has been discussed in detail in this paper. Optimum hose and pipe assembly designed for passenger car automatic transmission cooling system was subjected to test bench and vehicle level test.
Tongaonkar, Yogesh Manohar, Patel, Hiral, Tendulkar, Vishveshvar, Bhosale, Vikas
Development of an Innovative Transmission System for Two-Wheelers Using TRIZ Methodology2019-26-03691/9/2019
In a developing country like India, Two-wheelers dominate the automotive market with around 80% market shares. In Indian city traffic conditions, driving a two wheeler is a tiresome job. Manual transmission makes this task even further uncomfortable. So an automatic transmission is a better solution. A new automatic transmission system is developed which can reduce fatigue of drivers. Steps of ARIZ (Algorithm for Inventive Problem Solving) were followed. Ideas or concepts for the design were proposed from various fields and were compared for various parameters like size, weight, complexity, manufacturability, feasibility, efficiency and cost. They were also compared with the existing transmission systems. Based upon the results of the comparison, 5 designs were selected and they were analyzed thoroughly. Finally one design was selected. It was further studied in detailed and its improving and worsening features are noted and with the help of contradiction matrix and 40 principles contradictions were removed. S-Curve for the new system is predicted and the effects of the new design on super system are shown with the help of system operator (25 windows).
Moulick, Enanko, Wani, Kiran
AMT Reverse Gear Engagement Dynamics and Control2019-26-00461/9/2019
Now a day’s automated manual transmissions (AMT) are getting popular because of hassle-free gear shifting and improved fuel economy. OEMs are converting their existing manual gearbox to AMT gearbox with solution like hydraulic or electric AMT kit that replaces the manual shift mechanism to automated actuators. Generally, in manual gearbox, the operational principal of reverse gear is sliding mesh. Due to sliding mesh gear arrangement, it can create interruption for gearshift while controlling shift actuators. In this paper, reverse gear shift arrangement and its operational dynamics at different operating condition has been studied and analyzed in detail. Based on status of vehicle, to ease the gearshift, engagement flow process proposed. The control methods that increases probability of smooth and easier shifting in all operating condition discussed in detail. The developed control algorithm discussed along with its implementation on real vehicle and results.
Prajapati, Gaurang, Penta, Amar, Warule, Prasad
Reduction in Human Effort in Shifting and Selection Forces in Manual Transmission system2019-26-03661/9/2019
Transmission system is important part of automobile. In the current era of automobile, there are two types of gear shifting mechanism: manual and automatic. Manual gear shifting mechanism is complex and require much effort for shifting and selection of gear so to surmount much effort by kinematic analysis of linkages, joints ergonomically. By changing these parameters in gear shifting mechanism it gives flexibility and less effort for shifting and selection of gear. It also reduce feasibility of error of shifting and selection of gear. Transmission system is modeled in CREO 2.0 and measuring and data analysis of the shift and selection forces of gear was done with the load sensor shown in Figure 6 and programming was done in LABVIEW 2015. The final cause of this technical paper is to decrease physical effort by driver for shifting and selection of gear.
Pandey, Avi, Gupta, Sudhir
Development of 2 Speed Automatic Transmission for Battery Electric Two Wheelers2019-26-01091/9/2019
Improving vehicle performance in terms of both torque and power is a strong customer need in both conventional and electric vehicles. In this work, different two speed automatic transmission (AT) concepts are developed to improve the energy efficiency and performance of battery electric two wheelers. Developed transmission systems are simple, compact and cost effective and results in relatively high energy efficiency of an electric motor. The unique shift control strategy ensures motor to operate at higher efficiency zones to minimize the overall energy consumption. Virtual simulations of electric vehicle were carried out for different driving conditions and optimal transmission ratios were determined. Mechanical behaviors such as gear shift characteristics, linear and angular velocities, inertial forces of each components are analyzed by using Multi body dynamics simulation. Forces predicted here are further used for durability studies of these components. The developed system combines superior shifting accuracy, high transmission efficiency with increased grade ability and results in substantial improvement in acceleration while retaining top vehicle speed without much compromise.
Satyanarayana, PS, Ayyappath, Prajod, Jaiswal, Animesh, Iyer, Ramkumar, Charantimath, Siddalingesh
Gearshift Quality Sensitivity Analysis2019-26-03281/9/2019
Gearshift quality is a perceived quality parameter. Hence, is getting much importance because of the increased awareness about comfortable and refined driving experience, especially in the case of passenger cars. When the topic of gearshift feeling is broached in manual transmission vehicles, synchronizer pack (shifter sleeve, engaging gear, strut, synchronizer and gear synchro ring assembly) have been the focus point for optimization. Synchronizer type (single, double or triple cone), lining material, datch chamfer angle of shifter sleeve/synchro ring of gear/synchronizer, all of these have been extensively studied in the past to improve the gearshift quality. With stringent timelines for vehicle development, OEMs prefer to use off-the-shelf powertrain systems developed by powertrain manufacturers. Due to this, avenues to refine gearshift feel gets reduced to a large extent and hence refinement becomes difficult. The scope of this paper is to discuss gearshift quality parameters used to assess the gearshift feel of a vehicle. It primarily examines ways to refine the gearshift quality by optimizing the external gearshift mechanism and other powertrain aggregates. It also extends to a sensitivity analysis of gearshift cables, gear shifter, dead weights and driveshaft on gearshift quality. Objective parameters were evaluated on vehicle level to understand the aspects of the gearshift, which when tweaked, resulted in an improved shift feel. Different proposals with regard to possible avenues were worked out for possible fine-tuning of the selected parameters. These were then validated on the vehicle. During the evaluation and optimization of gearshift quality, GSQA kit from M/s Ricardo was used to evaluate the gearshift quality.
Patel, Hiral, Tendulkar, Vishveshvar, Baid, Himanshi, Bhosale, Vikas, Bhavikatti, Gururaj
Manufacturing of Transmission Quill Gear by Sinter Hardening2019-26-01651/9/2019
Transmission quill gears are hot forged steel parts often used in constant mesh manual transmissions. The quill gear, which helps to transmit the power from input drive shaft to output shaft through driving gears. It’s having external teeth which is positively engaged with driving gear and sleeve. During gear selection sleeve take load from input shaft and transmit to driven gear. Quill gear directly engaged with driving gears on outer surface and bearing in inner surface which needs to have high strength and durability. These properties can be improved by carburization heat treatment in existing design such processes can lead to increased costs. We have developed quill gear through powder metallurgical process and then cooled rapidly in the furnace to get high strength and wear properties. Material composition are optimized to suit for sinter hardening process conditions. Thus, we have succeeded in the development of quill gears via sinter hardening, thus eliminating the forging and second hardening process. This paper will have detailed discussion on material chemical composition, sinter hardening process, mechanical and metallurgical properties comparison and validation results.
Gunalan, Magendran, Deshmukh, Rahul, Bane, Uttam
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
Jeep's Gladiator takes up arms in midsize-pickup battle19AUTP01_141/1/2019
Maybe the only thing more surprising than the fact it's been more than a quarter-century since FiatChrysler's Jeep brand sold a pickup truck is that it's taken so long to pull the trigger in a U.S. auto market that's been truck-crazed for the better part of a decade. Blame Jeep planners. Or more-charitably attribute the glaring tardiness in launching a Jeep pickup to the reality that FiatChrysler had to navigate a recession and a couple of ownership changes before and during the market's transition to pickup mania. But the 2020 Jeep Gladiator is here, unveiled at the 2018 Los Angeles auto show looking like one of the surest things the auto business can conjure.
Visnic, Bill
Electric Vehicle with Multi-Speed Transmission: A Review on Performances and Complexities08-07-02-001112/4/2018
Electric vehicles (EVs) with multi-speed transmission offer improved performances compared to those with single speed transmission system in terms of top speed, fast acceleration, or gradeability along with driving range. In this study, relevant literature is extensively analyzed to explore the performances and associated complexities with multi-speed automatic manual/mechanical transmission (AMT) system in EVs. In EV powertrain, the only torque generator component is electric motor, which is not equally efficient throughout wider speed range. To the other end, vehicles need to run at different speeds in diverse driving conditions. The study shows that multi-speed transmission system enables efficient operation of electric motor by choosing an appropriate gear at different driving torque-speed demands and thus contributes to achieve desired vehicle performances at minimum energy consumption. To demonstrate the differences, both dynamic and economic performances with multi-gear system and single speed system are compared, and the results of various techniques are presented in the form of tables and bar charts. A quantitative analysis is also conducted to show the performance improvement achievable by employing multi-speed transmission concept in EVs. Apart from additional mass, gear ratio selection and torque interruption during gear shifting are major obstacles to improve drivetrain efficiency and riding comfort in EVs with multi-speed transmission system. For optimal gear ratio in transmission system, genetic algorithm (GA) is found to be implemented in most articles. It is also observed that variable shift schedule needs to be considered during the optimization process to get the paramount gear ratios. Tables and bar charts are used to show the results of recent relevant works to these issues. In this article, the readers would gain a comprehensive knowledge on how multi-speed transmission technology can outperform the single speed system within EV platform and what the inherent challenges are.
Ahssan, Md Ragib, Ektesabi, Mehran Motamed, Gorji, Saman Asghari
Torsional Fluctuations Consideration while Design of Synchro Rings2018-01-18239/10/2018
In today’s manual transmissions of car, gearshift system requires high performance with particular emphasis on low effort, minimal travel and positive feel. To meet these targets, a high capacity multi cone synchronizers along with higher co-efficient of friction material used for lower gears. The design of synchronizer with these specifications is influenced by torsional fluctuations from engine. Excessive torsional vibrations leads to wobbling of synchro rings within the peripheral clearances with surrounding parts. Wobbling leads to abrasion wear of frictional area of synchro ring causing grating or crashing noise of gears during shifting. This paper presents the optimization of the multiple cone synchronizer design exposed to excessive torsional vibrations and validation of the same on test bench during development stage instead vehicle level validation.
Tawhare, Nitin, Aswale, Dhananjay, Ponkshe, Makarand
Super Low Viscosity ATF; AW-22018-01-17569/10/2018
Reducing loss torque in automatic transmissions (ATs) is a key factor in improving fuel economy. A promising approach is to reduce the viscosity of the Automatic Transmission Fluid (ATF) so as to minimize churning loss. Aisin AW and JXTG Nippon Oil & Energy Corporation have developed a super low viscosity ATF, called “AW-2”, which has approximately 50% lower kinematic viscosity at 40 °C compared to the conventional ATF “AW-1”. It is generally understood that if the viscosity of an ATF is too low, it can have a negative impact on the fatigue life of components such as gears and bearings, and possibly lead to increased wear or seizure. AW-2 was designed to solve these problems via the application of two key technologies. The first is a high performance base oil with a low traction coefficient, which translates to low viscosity under high pressure conditions. This decreases the shear resistance between sliding surfaces under elastohydrodynamic lubrication (EHL) conditions, which contributes in improving the fatigue life of bearings and other components. The second is an ester type base oil with high polarity. It was found that the amount of ester base oil used has a major influence on fatigue life. The adsorption of esters onto metal surfaces is thought to improve lubricity in severe lubrication conditions. Durability tests were performed in a wide range of conditions, using gear and bearing components and actual transmission units, and it was confirmed that AW-2 outperforms AW-1, despite its super low viscosity. Furthermore, AW-2 reduced loss torque in the transmission by approximately 10% compared to AW-1.
Masuda, Kohei, Nakao, Hajime, Komatsubara, Hitoshi, Kurosawa, Osamu, Yamada, Katsuhito, Ishikawa, Kazunori, Mori, Atsushi
Determination of the amplitude of the friction forces variation inherent to a coastdown test (typical noise amplitude), comparing it with the aerodynamic drag force and raise the sensitive of the coastdown test to the variation of the vehicle coefficient of drag (Cd)2018-36-01879/3/2018
This paper has the objective to present the study of typical friction forces variation (noise) on a vehicle coastdown test @ 110 km/h, correlate with the drag force raised in wind tunnel and finally compared them to determine the sensitivity of Cd variation which can be detected on an “A to B” coastdown test procedure. As “A to B”, comparison test means testing the vehicle with a known aero Cd compare to another one, creating real technical parameters. For this study, we used real data from certification coastdowns tests for a same vehicle configuration in the most controlled possible conditions (all tests performed in CAPG track facilities) and real vehicle aerodynamic data raised from the wind tunnel.
Holl, Alexandre Faraco, Santos, Alex Cardoso
Development of a New 6-Speed FWD Manual Transmission2018-01-03924/3/2018
Environmental awareness has increased on a global scale which pushed for a heavier demand for weight reduction and high transmission efficiency on manual transmissions (hereafter referred to as the “MT”) in improving vehicle driving and fuel economy performance. Comfortable shift feel is also continuously in demand by the customer because its sensitive performance can be directly recognized by the driver which may determine the transmission’s merchantability. The newly developed 6-speed MT (hereafter referred to as the “6MT”) has achieved size reduction (compact size), weight reduced, better fuel efficiency, and improvement in the shift feel which will continue to maintain its’ competitiveness in the future.
Saito, Daisuke, Tanaka, Takayuki, Naito, Koji, Kato, Junichi, Shimane, Yoshichika, Takagaki, Masao, Naito, Koji, Kato, Junichi, Shimane, Yoshichika, Takagaki, Masao
Fuzzy PID Based Optimization of Starting Control for AMT Clutch of Heavy-duty Trucks2018-01-11664/3/2018
Starting control has become a troublesome issue in the developing field of the control system for heavy-duty trucks, due to the complexity of vehicle driving and the variability of driver's intention. The too fast clutch engagement may result in serious impact, influence on the comfort and fatigue life, and even the engine flameout, while the too slow clutch engagement may lead to long time of friction, the increased temperature, and accelerated wear of friction pair, as well as influence on the power performance and fatigue life[1]. Therefore, the key technique of starting control is clutch engagement control, for which the fuzzy PID based optimization of starting control for AMT clutch is proposed, with the pneumatic AMT clutch of heavy-duty trucks as the research object. Firstly, the structure and working principle of the clutch control system is introduced, and the working characteristics of the clutch is analyzed; Secondly, the clutch engagement process is analyzed, and the dynamic analysis is carried out for the starting process, to establish the theoretical model; Then, the common PID algorithm is improved to optimize its parameters by the fuzzy inference method of the error change rate and error rate of clutch position, and the fuzzy PID based starting controller is designed. Finally, the vehicle dynamics model and clutch control model are established for simulation by using MATLAB/SIMULINK, and the real vehicle test is also carried out to verify the designed optimal PID control algorithm. The simulation and test results show that the fuzzy PID based starting controller results in better target tracing performance of the clutch engagement displacement, compared to normal PID control, and the starting performance has been improved with the smoother starting process.
Lei, Yulong, Liu, Zengyin, Fu, Yao
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
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
Modelling of Power Losses of Transmission Synchronizers in Neutral Position2018-01-12284/3/2018
Developing an energy-efficient powertrain system is a solution for environment-friendly vehicles. Furthermore, it also enhances the performance of vehicles. In powertrain system, transmission plays an important role in terms of vehicle dynamic performance and energy consumption. Therefore, a lot of researches have been conducted on modelling power losses inside the transmission. Basically, the power losses in transmission consist of bearing losses, drag torque losses on gear blank that is immersed in the oil and gear mesh losses due to the sliding frictional force on gear flank. According to some experiments in the latest literatures, power losses of synchronizers cannot be neglected, when its shift sleeve is in neutral position. Principally, power losses of synchronizers in neutral position mainly come from load independent drag torque. The drag torque is generated by the shear torque of lubrication in the gap (or gaps) between synchronizer ring and synchronizer cone, which are rotating at different speed. In this paper, a drag torque model of synchronizer units in neutral position is built up based on mechanism of tribology lubrication. Several factors are considered in the model, for example, synchronizer geometry (cone angle, face width, etc.) and lubrication factors (viscosity, oil volume, etc.). Furthermore, the power losses of synchronizer under different oil injection methods are considered and separately discussed in the paper. In the end, validations are conducted. The amplitude and tendency of simulation results agree well with test data. In the future, the model of synchronizer power losses in neutral position will be further modified and it is planned to apply it into a study case for a manual transmission.
Shen, Ye, Liu, Zhihong, Rinderknecht, Stephan
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
Design Optimization of the Transmission System for Electric Vehicles Considering the Dynamic Efficiency of the Regenerative Brake2018-01-08194/3/2018
In this paper, gear ratios of a two-speed transmission system are optimized for an electric passenger car. Quasi static system models, including the vehicle model, the motor, the battery, the transmission system, and drive cycles are established in MATLAB/Simulink at first. Specifically, since the regenerative braking capability of the motor is affected by the SoC of battery and motors torque limitation in real time, the dynamical variation of the regenerative brake efficiency is considered in this study. To obtain the optimal gear ratios, iterations are carried out through Nelder-Mead algorithm under constraints in MATLAB/Simulink. During the optimization process, the motor efficiency is observed along with the drive cycle, and the gear shift strategy is determined based on the vehicle velocity and acceleration demand. Simulation results show that the electric motor works in a relative high efficiency range during the whole drive cycle. The energy economy of the case-study vehicle with the optimized a two-speed transmission is also compared to that of the baseline vehicle with fixed-ratio reduction gear.
Zhao, Bolin, Lv, Chen, Hofman, Theo, Steinbuch, Maarten, Zhang, Junzhi, Cao, Dongpu
Development of New Continuously Variable Transmission for 2.0-Liter Class Vehicles2018-01-10624/3/2018
Toyota has developed a new continuously variable transmission (CVT) called "Direct Shift-CVT" which is for 2.0-liter class vehicles. This CVT provided not only power transmission by a metal belt held with a conventional pulley but also additional gear mechanism. This CVT is developed to improve fuel efficiency, acceleration characteristic, and quietness. At this CVT, the startup low gear ratio is achieved by gear mechanism and the power is switched by clutches. Since the belt-pulley portion can be realized to be wide range by using only high gear ratio range, the input load into belt-pulley portion is reduced and unprecedented compact and high efficient belt-pulley portion is established. Consequently, the high efficiency in all fields from startup acceleration to high speed driving is achieved to improve fuel efficiency. In order to achieve emotional driving performance, driving force is optimized by switching the gears and the belt-pulley portion based on the operation of drivers and driving scenes. Moreover, a new control technology improves shift response in sequential shiftmatic mode. This paper describes details about new control technology applied to the Direct Shift-CVT, and some concrete examples of improvements of vehicle characteristics.
Niii, Daisuke, Kondo, Hiroki, Washio, Taichi, Kuwabara, Shinya, Shimizu, Masanori
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