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Utilization of TGA Flynn-Wall and Arrhenius Analysis for Rapid Prediction of Automotive PVC Cable Performance

Delphi Corp.-Robert A. Smith
Delphi E/EA-Allison Ward, Daniel Brintnall
Published 2017-03-28 by SAE International in United States
Both pellet raw material and resulting extruded insulation samples were obtained from three grades of PVC used to produce automotive insulation and were examined for thermal stability on a Thermogravimetric Analyzer (TGA). The Flynn Wall technique was used to obtain degradation activation energies by plotting ln(heating rate) vs 1/T and using a literature value of 7% weight loss as the point of performance failure. The Arrhenius relationship was used to predict multiple year lifetimes at 100°C from the multiple hour degradation times observed on the TGA at 200°C. The insulation specimens of two of the samples were found to be significantly less thermally stable than the pellets - indicating slight decomposition occurred during extrusion onto the cable core. All cable insulation samples predicted service lifetimes many times the expected auto life. A PVC insulation sample was examined for failure at various oven aging temperatures using ASTM D3032 mandrel wrap testing. The weight loss for failure was calculated by substituting the oven age time and temperature into the Arrhenius relationship and using an activation energy obtained…
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Molecular Analysis of Automotive Electrical Components Contaminated with Engine and Powertrain Performance Fluids

Delphi Corp.-Robert A. Smith, Christopher Rudzinskas
Published 2016-04-05 by SAE International in United States
Samples of 33% glass filled and unfilled poly(butylene terephthalate) [PBT] and nylon 66 (PA66) were injection molded into bars,which were immersed in common engine and powertrain fluids: antifreeze, motor oil and automatic transmission fluid for 25 days. Fluid uptake was measured at 1, 7, 18, and 25 days by gravimetry. Both PBT samples absorbed 0.2-0.25% antifreeze and 0.05 - 0.10% motor oil and automatic transmission fluid (ATF). Both DSC and DMA analysis showed no disruption of polymer thermal transitions or storage moduli. The glass filled PA66 sample absorbed 2.5% antifreeze and 0.25-0.3% of motor oil and ATF and showed an 80°C reduction in the tan delta maximum on DMA. The unfilled PA66 sample absorbed 7% antifreeze and 0.2-0.3% of motor oil and ATF also showed a tan delta maximum 80°C less than the unexposed control. Creep analysis was conducted on the unfilled nylon sample and compared to a virgin material. The softer antifreeze-exposed sample had the expected higher instantaneous strain; however, it had a much reduced viscoelastic response and less permanent deformation. This behavior was…
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Low Pressure Cooled EGR Transient Estimation and Measurement for an Turbocharged SI Engine

Delphi Corp.-Feilong Liu, Jeffrey M. Pfeiffer, Ron Caudle, Peter Marshall, Peter Olin
Published 2016-04-05 by SAE International in United States
Low Pressure Cooled Exhaust Gas Recirculation (LP EGR) is an attractive technology to reduce fuel consumption for a spark-ignition (SI) engine, particularly at medium-to-high load conditions, due to its knock suppression and combustion cooling effects. However, the long LP EGR transport path presents a significant challenge to the transient control of LP EGR for the engine management system. With a turbocharged engine, this is especially challenging due to the much longer intake induction system path compared with a naturally aspirated engine.Characterizing and modeling the EGR, intake air mixing and transport delay behavior is important for proper control. The model of the intake air path includes the compressor, intercooler and intake plenum. It is important to estimate and track the final EGR concentration at the intake plenum location, as it plays a key role in combustion control.This paper describes the development of a real-time, implementable model for LP EGR estimation. Test results from an engine dynamometer are included that validate the model under steady-state and transient operation. The development and implementation of instrumentation to enable accurate…
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Estimation Algorithms for Low Pressure Cooled EGR in Spark-Ignition Engines

SAE International Journal of Engines

Delphi Corp.-Feilong Liu, Jeffrey Pfeiffer
  • Journal Article
  • 2015-01-1620
Published 2015-04-14 by SAE International in United States
Low-pressure, Cooled Exhaust Gas Recirculation (LPC EGR) brings significant fuel economy, NOx reduction and knock suppression benefits to a modern, boosted, downsized Spark Ignition (SI) engine. As a prerequisite to design an engine control system for LPC EGR, this paper presents development of a set of estimation algorithms to accurately estimate the flow rate, pressure states and thermal states of the LPC EGR-related components.
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Creep and Stress Relaxation Evaluation of Virgin and Thermally Aged Glass-Filled Poly(butylene terephthalate) used in Automotive Electrical Connector Applications for Electrically-Powered Vehicles by Dynamic Mechanical Analysis

SAE International Journal of Materials and Manufacturing

Delphi Corp.-Robert A. Smith, Mikel Petty
  • Journal Article
  • 2015-01-0603
Published 2015-04-14 by SAE International in United States
Poly(butylene terephthalate) stock with 0, 15, and 30% glass fiber filler, used in the housings of electrical connectors on hybrid and electric vehicles, was examined by creep and stress relaxation for viscous deformation and modulus loss at 25, 75, 125, and 150°C. Sets of virgin and aged samples were examined within each set then compared to each other.Both the virgin and aged samples showed little viscous deformation or modulus reduction at 25°C, which was below the Tg of 40°C. Thermoplastic creep and stress relaxation was observed at the temperatures above Tg with, expectedly, more sample distortion and stiffness loss observed at higher test temperatures and lower filler contents both in virgin and unaged samples.Aged samples became stiffer, and more resistant to irrecoverable strain and stress relaxation than virgin samples indicating connectors to have a “self-healing” aspect through in-service use at elevated temperatures. This phenomenon was noted in literature and verified as arising from thermally-induced secondary crystallization in the aged samples by observation of increased crystalline content using DSC; and analysis of the variation of storage…
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Cold Performance Challenges with CNG PFI Injectors

Delphi Corp.-Raul Bircann, Youssef Kazour, Kenneth Dauer, Mahoro Fujita, Allan Wells, Daniel Francis Kabasin, Harry Husted
Published 2013-04-08 by SAE International in United States
Compressed Natural Gas (CNG) is gaining popularity as a viable alternate transportation fuel in many regions of the world. Injectors capable of delivering pressurized gaseous fuels have been developed for this emerging vehicular market segment. CNG fuel injectors must be designed to be compatible and durable with a very low lubricity gaseous fuel to meet automotive OEM life expectancy standards. Traditional gasoline injectors utilize a “hard/hard” sealing configuration, in which both the valve and seat are constructed out of hard metals. When properly lubricated with liquid fuels, these valves can meet vehicular injector leak and flow durability requirements. However, metal valves operating without lubrication can experience excessive wear, which leads to unacceptable levels of gas leakage and flow shifts. The use of elastomer-to-metal sealing surfaces minimizes leakage, but may cause cold ambient operation challenges. In this paper we will provide an overview of a compressed natural gas port fuel injector and associated test results for meeting both durability and cold performance challenges.
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Manufacturing Support Design for Low-Cost Instrument Clusters

Delphi Corp.-Sreedhar Thanthry
Published 2013-04-08 by SAE International in United States
All automotive ECUs are required to be designed for manufacturability. Sufficient support in the ECU product design needs to be incorporated early in the product life cycle for the product to be successfully and efficiently manufactured, necessitating serial communication capability in the design. However, in low-cost automotive Instrument Clusters the customer requirements for the product typically do not encapsulate serial communication, and the ECU is not required to support repair/rework out of field rejection. This paper delineates the said need, examines the challenges for manufacturability of low-cost Instrument Clusters and proposes a plausible design strategy to help the issue with a use-case instance.
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Large Eddy Simulation of GDI Single-Hole Flow and Near-Field Spray

SAE International Journal of Fuels and Lubricants

Delphi Corp.-Bizhan Befrui, Giovanni Corbinelli, Peter Spiekermann, Mark Shost
Wayne State Univ.-Ming-Chia Lai
  • Journal Article
  • 2012-01-0392
Published 2012-04-16 by SAE International in United States
The improvement of spray atomization and penetration characteristics of GDI multi-hole injector sprays is a major component of the engine combustion developments, in order to achieve the fuel economy and emissions standards. Significant R&D efforts are directed towards optimization of the nozzle designs, in order to achieve optimum multi-objective spray characteristics.The Volume-of-Fluid Large-Eddy-Simulation (VOF-LES) of the injector internal flow and spray break-up processes offers a computational capability to aid development of a fundamental knowledge of the liquid jet breakup process. It is a unique simulation method capable of simultaneous analysis of the injector nozzle internal flow and the near-field jet breakup process. Hence it provides a powerful toll to investigate the influence of nozzle design parameters on the spray geometric and atomization features and, consequently, reduces reliance on hardware trial-and-tests for multi-objective spray optimizations.This publication reports investigations of a single, axisymmetric nozzle-hole, pertinent to GDi multi-hole injector nozzle geometry, with the aid of the current state-of-the-art VOF-LES method. The focus of the study is the influence of nozzle degsign and geometric features on the plume…
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Engine Stop Position Estimation

SAE International Journal of Engines

Delphi Corp.-Martin Mueller
  • Journal Article
  • 2012-01-0720
Published 2012-04-16 by SAE International in United States
This paper describes a method to estimate the engine stop position using any production style crank position sensor, while accounting for possible engine rock-back. The approach is based on modeling the engine speed state, achieving robustness and ease of calibration by adapting the rubbing friction model component during the first part of engine coast-down, followed by open-loop modeling when the engine speed has dropped below the sensor signal validity threshold.
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Full-Time Gasoline Direct-Injection Compression Ignition (GDCI) for High Efficiency and Low NOx and PM

SAE International Journal of Engines

Delphi Corp.-Mark C. Sellnau, James Sinnamon, Kevin Hoyer, Harry Husted
  • Journal Article
  • 2012-01-0384
Published 2012-04-16 by SAE International in United States
A gasoline compression-ignition combustion system is being developed for full-time operation over the speed-load map. Low-temperature combustion was achieved using multiple late injection (MLI), intake boost, and moderate EGR for high efficiency, low NOx, and low particulate emissions. The relatively long ignition delay and high volatility of RON 91 pump gasoline combined with an advanced injection system and variable valve actuation provided controlled mixture stratification for low combustion noise.Tests were conducted on a single-cylinder research engine. Design of Experiments and response surface models were used to evaluate injection strategies, injector designs, and various valve lift profiles across the speed-load operating range. At light loads, an exhaust rebreathing strategy was used to promote autoignition and maintain exhaust temperatures. At medium loads, a triple injection strategy produced the best results with high thermal efficiency. Detailed heat release analysis indicated that heat losses were significantly reduced. At higher loads, a late-intake-valve-closing strategy was used to reduce the effective compression ratio. For all tests, intake air temperature was 50 C.3D CFD simulations of fuel injection, mixing, and combustion were…
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