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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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IC engine internal cooling system modelling using 1D-CFD methodology

FCA Engineering India Pvt Ltd-AMIT KUMAR, Tharunnarayanan Arthanari, VAIBHAV PATIL, Kamalakannan J
FCA Engineering India Pvt, Ltd.-Dhananjay Sampat Autade
  • Technical Paper
  • 2020-01-1168
To be published on 2020-04-14 by SAE International in United States
Internal combustion engine gets heated up due to continuous combustion of fuel. To keep engine working efficiently and prevent components damage due to very high temperature, the engine needs to be cooled down. Based on power output requirement and provision for cooling system, every engine has it’s unique cooling system. Liquid based cooling systems are majorly implemented in automobile. It’s important to keep in mind that during design phase that, cooling the engine will lower the power to fuel consumption ratio. Therefore, during lower ambient conditions, the cooling system should be able to uniformly increase the temperature of the engine components, engine oil and transmission oil. This is achieved by circulating the coolant through cooling jacket, engine oil heater and transmission oil heater, which will be heated by the combustion heat. The objective of this study is to build a steady state 1D-model of cooling system; comprising of water pump, cooling jacket, engine head, thermostat, radiator, cabin heater, engine and transmission oil heaters with plumbing system. This 1D model is used to simulate vehicle drive…
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Hybrid Powertrain Choices for Emerging Engine Technologies

Aramco Research Center-Vincent Costanzo
Argonne National Laboratory-Ram Vijayagopal, Daniela Nieto Prada
  • Technical Paper
  • 2020-01-0440
To be published on 2020-04-14 by SAE International in United States
US department of energy estimates the peak efficiency of a modern spark ignited naturally aspirated Otto cycle engine to be 36%. Atkinson cycle engines are estimated to get 40% peak efficiency. Most engines can achieve this peak efficiency only for a limited operating region. Hybrid powertrains enable engine to operate in this efficiently. Overall efficiency is improved by shutting down engine during idle events and by adjusting the operating speed and load on the engine using electric machines. The choice of the powertrain and component sizes depends on the engine characteristics, drive cycles and vehicle technical requirements. This study examines what type of powertrains will be suitable for more efficient engines that are likely to be available in the near future. Some of these technologies achieve higher efficiency with a trade off on power or by accepting a more restrictive operating region. An appropriate powertrain choice can still enable such an engine to be a viable option for an automobile. Using simulation tools, 14 different engine technologies are evaluated in this paper for their fuel…
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Acoustic characteristics prediction and optimization of wheel resonators with arbitrary section

SAIC Motor Corporation Limited-Yimin Sun, Junlei Mao
Tongji Univ.-Rong Guo, Tiantian Mi
  • Technical Paper
  • 2020-01-0917
To be published on 2020-04-14 by SAE International in United States
Tire cavity noise of pure electric vehicles is particularly prominent due to the absence of engine noise, which are usually eliminated by adding Helmholtz resonators with arbitrary transversal section to the wheel rims. This paper provides theoretical basis for accurately predicting and effectively improving acoustic performance of wheel resonators. A hybrid finite element method is developed to extract the transversal wavenumbers and eigenvectors, and the mode-matching scheme is employed to determine the transmission loss of the Helmholtz resonator. Based on the accuracy validation of this method, the matching design of the wheel resonators and the optimization method of tire cavity noise are studied. The identification method of the tire cavity resonance frequency is developed through the acoustic modal simulation and test. A scientific transmission loss target curve and fitness function are defined according to the noise characteristics. Combing the transmission loss prediction theory and particle swarm algorithm, the structure parameters of the wheel resonator are optimized. A remarkable attenuation of tire cavity resonance can be observed through test results.
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Using Transmission Data to Isolate Individual Losses in Coastdown Road Load Coefficients

US Environmental Protection Agency-Andrew Moskalik
  • Technical Paper
  • 2020-01-1064
To be published on 2020-04-14 by SAE International in United States
As part of the U.S. Environmental Protection Agency’s continuing assessment of advanced light-duty automotive technologies in support of regulatory and compliance programs, multiple transmissions have been benchmarked to determine their efficiency during operation. The benchmarking included a modified “coastdown test,” with the transmission on an engine dynamometer, to measure the transmission output drag as a function of speed while in neutral. The transmission drag data can be represented in quadratic form, similar to that used for vehicle coastdown test results, as F0 + F1V + F2V2, where V is the vehicle velocity. When evaluating the transmission test data, the relationships among the three coefficients found to be highly predictable, and in some cases the magnitude of the coefficients were quite large. Additionally, for some tested transmissions the deviation between the quadratic regression and the measured drag at individual velocities can be significant. To evaluate the effect of transmission losses in vehicle coastdown tests, the coastdown and dynamometer coefficients were pulled from the EPA’s published “Data on Cars used for Testing Fuel Economy” for an entire…
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Utilization of bench testing in vehicle thermal system development for extreme cold ambient condition

FCA-Sadek Rahman
  • Technical Paper
  • 2020-01-1390
To be published on 2020-04-14 by SAE International in United States
Automotive thermal systems are becoming complicated each year. The powertrain efficiency improvement initiatives are driving transmission and engine oil heaters into coolant network design alternatives. The initiatives of electrified and autonomous vehicles are making coolant networks even more complex. The coolant networks these days have many heat exchangers, electric water pumps and valves, apart from typical radiators, thermostat and heater core. Some of these heat exchangers including cabin heaters deal with very small amount of coolant flow rates at different ambient conditions. This paper describes how viscosity can be a major reason for simulation inaccuracy, and how to deal with it for each component in the coolant network. Both experimental and computational aspects have been considered in this paper with wide range of ambient temperatures. Methods have been proposed to handle these issues in the simulation phase at the early phase of automotive thermal system development, especially during extreme cold ambient conditions.
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Development of GM 10-Speed Allison Heavy Duty (HD) Transmission

General Motors-Chi Teck Lee, David Ames, Brett Caldwell, Matthew Knoth, Timothy Reinhart, Jeffrey Kelly, German Tanasi
TCS-Rajesh Kannan
  • Technical Paper
  • 2020-01-0438
To be published on 2020-04-14 by SAE International in United States
This paper describes the development of GM 10-Speed Allison Heavy Duty (HD) Transmission. The trend of engine power and towing capacity in the automotive heavy-duty truck segment has been steadily climbing for a past 10 years. The development of GM 10-Speed Allison Heavy Duty Transmission is designed to be best in class for towing performance with no compromise in fuel economy. GM 10-Speed Allison Heavy Duty Transmission also gives the customers the option to order an integrated power transfer unit to improve the installation of power transfer or generation accessories. GM Allison HD truly brings the best of towing performance and fuel economy to the customers.
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Minimizing Disturbance Detection Time in Hydraulic Systems

General Motors-Paul Otanez, Ramadityanand Bhogadi
  • Technical Paper
  • 2020-01-0263
To be published on 2020-04-14 by SAE International in United States
In a hydraulic system, parameter variation, contamination, and/or operating conditions can lead to instabilities in the pressure response. The resultant erratic pressure profile produces reduced performance that can lead to hardware damage. Specifically, in a transmission control system, the inability to track pressure commands can result in various types of slip and disturbances to the driveline. Therefore, it is advantageous to identify such pressure events and take remedial actions. The challenge is to detect the condition in the least amount of time while minimizing false alarms. In this study, cross and auto-correlation techniques are evaluated for the detection of pressure disturbances. The performance of the detectors is measured in terms of speed of detection and robustness to: 1) measurement noise, and 2) disturbance parameter uncertainty (frequency and amplitude). The implications in terms of computations and memory utilization of implementing the detectors in real-time embedded systems are also discussed. Both simulation and hardware examples are presented. The hardware experiment is performed in a hydraulic system with low damping composed of a solenoid and a regulator valve…
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Benchmarking a 2018 Toyota Camry UB80E Eight-Speed Automatic Transmission

US Environmental Protection Agency-Andrew Moskalik, Mark Stuhldreher, John Kargul
  • Technical Paper
  • 2020-01-1286
To be published on 2020-04-14 by SAE International in United States
As part of the U.S. Environmental Protection Agency’s (EPA’s) continuing assessment of advanced light-duty automotive technologies in support of regulatory and compliance programs, a 2018 Toyota Camry UB80E front wheel drive 8-speed automatic transmission was benchmarked to determine the losses in operation. The transmission was installed in an engine dynamometer test cell equipped with the 4-cylinder engine from the 2018 Toyota Camry and inline torque transducers to measure transmission loads. A series of tests were conducted to determine the losses associated with the transmission operation, including transmission torque loss in each gear, torque converter K factor, neutral “coastdown” losses, idle torque, and oil temperature effects. The transmission benchmark data and associated engine data were used as inputs to EPA’s Advanced Light-duty Powertrain and Hybrid Analysis (ALPHA) vehicle simulation model. The ALPHA model simulated the GHG emissions from the 2018 Toyota Camry containing this engine and transmission, and the results were compared to vehicle chassis dynamometer test to validate the model. The torque loss map for the Toyota UB80E was then compared to other benchmarked transmission…
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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…