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Thermal Modeling of DC/AC Inverter for Electrified Powertrain Systems

FCA US LLC-Meng Li, Bruce Geist
Gotion, Inc.-Fan He
  • Technical Paper
  • 2020-01-1384
To be published on 2020-04-14 by SAE International in United States
A DC-to-AC main Power Inverter Module (PIM) is one of the key components in electrified powertrain systems. Accurate thermal modeling and temperature prediction of a PIM is critical to the design, analysis, and control of a cooling system within an electrified vehicle. PIM heat generation is a function of the electric loading applied to the chips and the limited heat dissipation within what is typically compact packaging of the Insulated Gate Bipolar Transistor (IGBT) module inside the PIM. This work presents a thermal modeling approach for a 3-phase DC/AC PIM that is part of an automotive electrified powertrain system. Heat generation of the IGBT/diode pairs under electric load is modeled by a set of formulae capturing both the static and dynamic losses of the chips in the IGBT module. A thermal model of the IGBT module with a simplified liquid cooling system generates temperature estimates for the PIM. Temperatures of chips, baseplates, and sinks are predicted from electric input loads. A case study is provided in wh ich the PIM thermal model is coupled with…
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A Case Study on Reducing the Fuel Pulse Noise from Gasoline Engine Injectors

FCA US LLC-Weiguo Zhang, Toon Tan, John Malicki, Glenn Whitehead
  • Technical Paper
  • 2020-01-1276
To be published on 2020-04-14 by SAE International in United States
Vehicle NVH performance is a very important consideration for vehicle buyers in the marketplace. There are many noise sources from the fuel system to generate noise in a vehicle. Among them, the pressure pulsations due to the rapid opening and closing of gasoline engine injectors can cause undesirable fuel pulse noise inside the vehicle cabin. As the pressure pulsation propagates in the fuel supply line toward to rear end of the vehicle, the pressure energy is transferred from fuel lines to the vehicle underbody through clips and into the passenger compartment. It is crucial to attenuate the pressure pulsation inside the fuel line to reduce the fuel pulse noise. In this paper, a case study on developing an effective countermeasure to reduce the objectionable fuel pulse noise of a V8 gasoline injection system is presented. First, the initial interior noise of a prototype vehicle was tested and the objectionable fuel pulse noise was exhibited. The problem frequency ranges with pulse and ticking noise content were identified. Several test iterations on root causing analysis and countermeasures…
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Experimental Study on Static and Fatigue Behavior of a Short Glass Fiber Reinforced Polypropylene

FCA US LLC-Mingchao Guo, Congyue Wang, Jian Tao, Ramchandra Bhandarkar
InDepth Engineering Solutions-Johnson Joseph
  • Technical Paper
  • 2020-01-0190
To be published on 2020-04-14 by SAE International in United States
One approach of reducing vehicle weight is using composite materials. Fiber reinforced polypropylene is one of the most popular composite materials. To improve accuracy in prediction of durability performance of structures made of this kind of composite material, static and fatigue properties of a 30% fiber reinforced polypropylene have been physically studied. This paper describes details of test coupon design, fabrication and test setup of both quasi static and fatigue tests. In this study, various fiber orientation (0, 20, 90 degrees & knit line), temperature (-40, 23 and 80 degree C), mean stress (R=-1.0, -0.5, -0.2, 0.1 and 0.4) have been considered and the result of the tests discussed.
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IC engine internal cooling system modelling using 1D-CFD methodology

FCA US LLC-Fu-Long Chang
FCA Engineering India Pvt., Ltd.-Dhananjay Sampat Autade, Amit Kumar, Tharunnarayanan Arthanari, Vaibhav Patil, Kamalakannan J
  • 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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Utilization of bench testing in vehicle thermal system development for extreme cold ambient condition

FCA US LLC-Masuma Khandaker, Ahmed Uddin, Vijay Sanikal, Kaji Fuad, Craig Lindquist, Gary Baker, 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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A study on the effect of different glasses and its properties on vehicle cabin during soaking at hot ambient conditions using 1D simulation

FCA US LLC-Murali Govindarajalu
FCA Engineering India Pvt., Ltd.-Karthik Subramanian, Prakashbabuji Danapalan, Saravanan Sambandan
  • Technical Paper
  • 2020-01-0956
To be published on 2020-04-14 by SAE International in United States
Increase in traffic conditions and global increase in the ambient temperature during the summer season, heat load in the vehicle cabin is also increasing, creating a huge thermal discomfort for the passengers. There are two scenarios in which these adverse conditions can be a problem, one is when driving the vehicle in traffic condition and another one is when the vehicle is parked in the open sun both during the summer season. While for the first scenario, at least the air conditioner can be switched on, for the soaking scenario the cabin temperature can reach alarming levels which may have serious discomfort and health effects on the human entering vehicle. Although there are options of remote switching on of air conditioners, they are restricted to vehicles having an automatic transmission only. Considering the different parts of cabin, the glasses occupy majority of the portion which is exposed to the sunlight and that transmit the heat directly into the cabin, which in turn is absorbed by different materials resulting in alarming temperature levels in cabin when…
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Review and Assessment of Multiaxial Fatigue Limit Models

FCA US LLC-Sean McKelvey, Eniyavan Subramanian, Yung-Li Lee
FCA Canada Inc.-Shiping Zhang
  • Technical Paper
  • 2020-01-0192
To be published on 2020-04-14 by SAE International in United States
The purpose of this paper is to provide a comparison of multiaxial fatigue limit models and their correlation to experimental data. This paper investigates equivalent stress, critical plane and invariant based multiaxial fatigue models. Several methods are investigated here and are compared based on their ability to predict multiaxial fatigue limits from data published in literature. The equivalent stress based LTJ model, with its ability to account for non-proportional loading, provides very accurate predictions of the fatigue limit under multiaxial loading. This accuracy comes from the model constant which is calculated based on multiaxial fatigue data. This is the only model investigated that requires multiaxial fatigue testing to generate the model parameters. All other models rely on uniaxial test results. Of the five stress based critical plane approaches investigated, the model proposed by Susmel and Lazzarin shows the greatest correlation with the multiaxial fatigue limit data. Overall, the invariant based prismatic hull method has the best agreement with the data found in literature. Additionally, a new critical plane model has been proposed. This new model…
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Investigate partial cabin air re-circulation strategy to improve HVAC system's heating performance using 1D simulation

FCA US LLC-Murali Govindarajalu
FCA Engineering India Pvt., Ltd.-Saurabh Belsare, Prakashbabuji Danapalan, Saravanan Sambandan
  • Technical Paper
  • 2020-01-0159
To be published on 2020-04-14 by SAE International in United States
In cold weather conditions, cabin heating performance is critical for retaining the thermal comfort. Heat is absorbed from the engine by circulating coolant through the engine water jacket and same will be rejected by the heater core. A variable speed blower is used to transfer heat from the heater core to the passenger compartment through floor ducts. The time taken to achieve comfortable cabin temperature determines the performance and capacity of heating ventilating and air conditioning (HVAC) system. In current automotive field, the engine options are provided to customers to meet their needs on the same vehicle platforms. Hence few engine variants cannot warm the cabin up to customer satisfaction. To improve the existing warm up performance of system, Positive thermal coefficient heater (PTC), electric coolant PTC heater, auxiliary pump etc. can be used which increases the overall cost of the vehicle. During warm-up, HVAC system operates in 100% fresh mode. In this study, Partial cabin re-circulation is investigated to understand the effect on the cabin warm-up. In order to demonstrate this phenomenon, a one…
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Application of Multivariate Control Chart Techniques to Identifying Nonconforming Pallets in Automotive Assembly Plants

FCA US LLC-Michael Huang, Yuqin Wang
University of Texas at San Antonio-Adel Alaeddini
  • Technical Paper
  • 2020-01-0477
To be published on 2020-04-14 by SAE International in United States
The Hotelling multivariate control chart and the sample generalized variance |S| are used to monitor the mean and dispersion of underbody data including the pallet information to identify the non-conforming pallets. An iterative procedure and the Gaussian mixture model (GMM) are used to rank the non-conforming pallets in the order of severity. The multivariate Hotelling T^2 test statistic with Mason-Tracy-Young (MYT) signal decomposition method are used to identify the features that are affected by the non-conforming pallets. These algorithms were implemented in Advanced Pallet Analysis module of FCA Body Shop Analysis Tool (BSAT). The identified non-conforming pallets are displayed in a scatter plot with different color for each pallet. The run chart of an affected feature confirms the nonconforming pallets by highlighting data points from the nonconforming pallet. The analysis module has been successfully used in the body shops of FCA plants. One example is presented to demonstrate the application.
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Light Duty Truck Rear Axle Thermal Modeling

FCA US LLC-Joydip Saha, Sadek Rahman
FCA-Mohammad Nahid
  • Technical Paper
  • 2020-01-1388
To be published on 2020-04-14 by SAE International in United States
More stringent Federal emission regulations and fuel economy requirements have driven the automotive industry toward more sophisticated vehicle thermal management systems to best utilize the waste heat and improve driveline efficiency. The final drive unit in light and heavy duty trucks usually consists of geared transmission and differential housed in a lubricated axle. The automotive rear axles is one of the major sources of power loss in the driveline due to gear friction, churning and bearing loss and have a significant effect on overall vehicle fuel economy. These losses vary significantly with the viscosity of the lubricant. Also the temperatures of the lubricant are critical to the overall axle performance in terms of power losses, fatigue life and wear. In this paper, a methodology for modeling thermal behavior of automotive rear axle with heat exchanger is presented to predict the axle lubricant temperature rise and study the effect of coolant temperature on the axle warm-up and efficiency for a typical EPA fuel economy driving cycle. Thermal axle consists of automotive rear axle with a heat…