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Gear Shift Pattern Optimization for Best Fuel Economy, Performance and Emissions

Chidhanand S
Mahindra & Mahindra Ltd-Srinivasan Lemuel Paulraj, Saravanan Muthiah
  • Technical Paper
  • 2020-01-1280
To be published on 2020-04-14 by SAE International in United States
FTP-75 drive cycle does not have a prescribed gear shift pattern and automotive OEM has the flexibility to decide. Conventionally the gear shift pattern was arrived at based on trial and error method typically in 10 to 12 Iterations on chassis dynamometer. It was a time consuming (i.e. ~ 3 to 4 months) and costly process. This approach also led to poor fuel economy (FE) labeling declaration. A simulation procedure needed to be established in such cases to generate a gear shift pattern that gives optimal trade-off amongst conflicting objectives (FE, Performance and Emissions). A simulation tool was developed in MATLAB to generate an optimum gear shift pattern. 3 different SUV/UV models were used as test vehicles in this study. Chassis dyno testing was carried out and data was collected using the base and optimized gear shift patterns. Dyno test results with optimized gear shift pattern showed FE improvement of ~ 4 to 5% while retaining the NOx margin well above engineering targets. This labeling FE improvement involved no additional cost impact as no hardware…
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Rolling Element Bearings - Advanced Modeling for Multibody Simulations

Siemens di Software NV-Pavel Jiranek
Siemens di Software NV / KU Leuven-Tommaso Tamarozzi
  • Technical Paper
  • 2020-01-0508
To be published on 2020-04-14 by SAE International in United States
The electrification of vehicles, together with the ever-increasing need for more lightweight and durable designs, is putting the NVH performances of the transmission in the spotlight since the generated noises are not masked by the internal combustion engine. To correctly estimate the performances of the transmission while still in the design-phase, predictive models for the main components of the gearbox are of paramount importance. This paper focuses on the modeling of rolling element bearings, a key component that is responsible of transmitting the vibrations from the gear pairs to the surrounding structure while introducing additional excitation frequencies. The modeling techniques use the relative displacement of the rings to compute the corresponding reaction forces by calculating the equilibrium of each rolling element. To do so, the interaction between the rolling elements and the raceways can be modeled employing two different contact models depending on the level of accuracy required. The contact models are, respectively, a Hertz-Based approach that allows for fast computations, and an EHL (Elasto-Hydrodynamic Lubricated) contact model which accounts for the effects of lubrication.…
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Active and Passive Control of Torsional Vibration in Vehicle Hybrid Powertrain System

Tongji Univ-Lijun Zhang, Dejian Meng, Jie Xu
Tongji Univ.-Shijuan Zhang
  • Technical Paper
  • 2020-01-0408
To be published on 2020-04-14 by SAE International in United States
The vibration characteristics of hybrid vehicles are very different from that of traditional fuel vehicles. In this paper, the active and passive control schemes are used to inhibit the vibration issues in vehicle hybrid powertrain system. Firstly the torsional vibration mechanical model including engine, motor and planetary gear subsystems is established. Then the transient vibration responses of typical working condition are analyzed through power control strategy. Consequently the active and passive control of torsional vibration in hybrid powertrain system are proposed. The active control of the motor and generator torque are designed and the vehicle longitudinal vibration is reduced. The vibration of the planetary gear system is ameliorated with passive control method by adding torsional vibration absorbers to power units. The vibration characteristics in vehicle hybrid powertrain system are effectively improved through the active and passive control.
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A Gear Shifting Indication Strategy of Eco-driving Vehicle

Jiangsu University-Nannan Hu
Jiangsu University-Ren He
  • Technical Paper
  • 2020-01-0966
To be published on 2020-04-14 by SAE International in United States
The current indication strategy of gear shifting indication system for manual transmission vehicles is developed based on the gear shifting strategy of the automatic transmission. In this paper, the driving data of several automatic transmission and manual transmission vehicles are collected. It is found that the shifting frequency of automatic transmission vehicles is significantly higher than that of manual transmission vehicles, which increases the fatigue of drivers. Aiming at this problem, an interval algorithm of gear shifting indication strategy is proposed based on the fuel consumption rate of engine in this paper. The strategy uses genetic algorithm to process the data of fuel consumption rate, finding the maximum and minimum values in the interval of torque and engine speed, and then the interval algorithm is adopted to transform the search of least fuel consumption value into the seeking of optimal interval to avoid the shifting busyness caused by the sudden change of the data of fuel consumption rate. The model of gear shifting indication strategy is established in Matlab/Simulink. Gear shifting tolerance is defined and…
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Test Bench for Static Transmission Error Evaluation in Gears

Politecnico di Torino-Carlo Rosso
Politecnico di Torino / GeDy TrAss-Tommaso Maggi, Claudio Marcellini, Fabio Bruzzone
  • Technical Paper
  • 2020-01-1324
To be published on 2020-04-14 by SAE International in United States
In this paper a test bench for measuring the Static Transmission Error of two mating gears is presented and a comparison with the results obtained with the code GeDy TrAss and a commercial Finite Element software are shown. Static Transmission Error is considered as the main source of overloads and Noise, Vibration and Harshness issues in mechanical transmissions. It is defined as the difference between the theoretical angular position of a gear under load in quasi-static conditions and the real one. This parameter strictly depends on the applied torque and the tooth macro and micro-geometry. The test bench illustrated in this work is designed to evaluate the actual Static Transmission Error of two gears under load in quasi-static conditions. In particular this testbed can be divided in two macro elements: the first one is the mechanism composed by weights and pulleys that generates a driving and a breaking torque up to 500 Nm. The second element is composed by two structures called “support”: one fixed to the floor and the other movable in order to…
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Vibration and Dynamic Analysis of Right-angle Geared Drives Considering the Influence of Gear-Shaft-Bearing Assembly Design

Marshall University-Xia Hua
  • Technical Paper
  • 2020-01-0415
To be published on 2020-04-14 by SAE International in United States
Dynamics of hypoid or spiral bevel gears like most high-speed precision gears employed in the powertrains of automobiles, commercial trucks, and off highway vehicles are significantly influenced by the design of the shafts and bearings. The finite element modeling approach is one of the useful methodologies applied to perform gear dynamic analysis. One of the major advantages of the finite element modeling approach is that it is able to account for the gear-shaft-bearing assembly design more accurately than other modeling approaches, for example, the lumped parameter modeling approach. In this paper, the finite element formulation, which can generally represent more complete characteristics of the gear-shaft-bearing assembly design, is employed to investigate how the key design changes of gear-shaft-bearing assembly influence the dynamics of spiral bevel gears. Accordingly, the underlying physics controlling these effects is also uncovered.
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A component level laboratory test methodology development for validating transmission bush

Mahindra & Mahindra Ltd.-Devanshu Kathrecha, Abhirup Chakraborty, Avinash Sirur, Jobin Sebastian, Jinesh Savla
  • Technical Paper
  • 2020-01-1409
To be published on 2020-04-14 by SAE International in United States
In the era of fierce competition, launching a defect free product on time would be the key to success. In 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. Transmission bush failure was observed in one of the transmissions during complete system level testing. Bushes are generally press fitted on the main shaft and counter shaft 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…
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Robust Design Optimization of Electronic Shifting Mechanism Considering Manipulation Comfort

Nanjing Univercity of Science&Technology-Jipeng Xie
Nanjing University of Science&Technology-Guolai Yang, Quanzhao Sun, Jianli GE, Xinghao Huang
  • Technical Paper
  • 2020-01-0605
To be published on 2020-04-14 by SAE International in United States
Electronic shifter is an important human-machine interaction device in modern vehicles. To reduce the influence of shifting mechanism and structural parameters on control comfort, in the early stage of product quality design, we proposed a grey relation grade dynamic robustness method. In this paper, based on the multi-body dynamic model of gear shifting mechanism that was verified by experiments, the dynamic shifting force can be calculated by the parameterized multi-body dynamic model, and used as dynamic response variables. Then we stablished the linear relationship between response variables and signal factors, and measured the correlation degree between response variables and signal factors by the grey relation grade analysis. And choose the groove structure’s parameters, the contact parameters, the compression spring’s stiffness and preload as controllable factors. The influence of each controllable factors on the response signals determined by the variance analysis, and get the order of controllable factors ,then taking the controllable factors with significant effects as the optimal combination when the variance of the response variable is the minimum, finally obtained the robustness parameters of…
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Ultralight axle development-fracture mechanics life predictions (40% weight reduction).

Magna Drivetrain of America Inc.-Michael Bujold
  • Technical Paper
  • 2020-01-0179
To be published on 2020-04-14 by SAE International in United States
This paper details the light weight developments with the use of fracture mechanics technology. Forty percent weight reduction was achieved in an automotive axle. Novel pinion cartridge, ring gear , and differential designs were incorporated in this project to achieve weight, efficiency, noise and performance targets. A fracture mechanics (crack growth model) was used to determine steel cleanliness levels required as component size was optimized based on processing variables(steel material properties, initial flaw size, residual stress, duty cycle analysis,...). Prototype hypoid gear samples made from two variations of steel cleanliness were used to qualify the crack growth models with and without the addition of shot peening to vary the residual stress profiles for life requirements. Housing material variations of aluminum and magnesium were used for additional weight reduction in this program.
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Optimum positioning of FIP drive system for Type-II BSVI engine based on coupled 1d “Valve-train – Chain drive” Dynamic analysis

VE Commercial Vehicles, Ltd.-Kaarthic Kaundabalaraman, Jasvir Singh Bisht, Hemantkumar Rathi
  • Technical Paper
  • 2020-01-1020
To be published on 2020-04-14 by SAE International in United States
The automotive industry is gearing up to meet the accelerated emission compliance changes posed by the government. This transition to eco-friendly system would also necessitate an automotive engineer to retain the engine packaging as compact and simple as possible. The packaging layout considered should not be at the expense of deteriorating engine performance. The work started with concept level layout development, with the aim of having simplified system with minimum number of components. The engine on which the work was carried out was 4cylinder 3Liter with OHC configuration A number of layouts were developed which included gear type, belt drive and integrated shaft arrangement for driving FIP. Each of these concepts were brainstormed with cons and pros, based on which two concepts were initially proposed for driving FIP system (i) Front Driven FIP (ii) Rear Driven FIP. The difference between the two layouts was that in the latter case the FIP system was directly driven through Exhaust Camshaft with gear type arrangement. For the above two proposed layouts, dynamic evaluation was done up-to Max intermittent…