Forrest Jehlik

Tahoe HEV Model Development in PSAT

Argonne National Laboratory (Argonne) and Idaho National Laboratory (INL), working with the FreedomCAR and Fuels Partnership, lead activities in vehicle dynamometer and fleet testing as well as in modeling activities. By using Argonnes Advanced Powertrain Research Facility (APRF), the General Motors (GM) Tahoe 2-mode was instrumented and tested in the 4-wheel-drive test facility. Measurements included both sensors and controller area network (CAN) messages. In this paper, we describe the vehicle instrumentation as well as the test results. On the basis of the analysis performed, we discuss the vehicle model developed in Argonnes vehicle simulation tool, the Powertrain System Analysis Toolkit (PSAT), and its comparison with test data. Finally, on-road vehicle data, performed by INL, is discussed and compared with the dynamometer results.

Simulated Real-World Energy Impacts of a Thermally Sensitive Powertrain Considering Viscous Losses and Enrichment

It is widely understood that cold ambient temperatures increase vehicle fuel consumption due to heat transfer losses, increased friction (increased viscosity lubricants), and enrichment strategies (accelerated catalyst heating). However, relatively little effort has been dedicated to thoroughly quantifying these impacts across a large set of real world drive cycle data and ambient conditions. This work leverages experimental dynamometer vehicle data collected under various drive cycles and ambient conditions to develop a simplified modeling framework for quantifying thermal effects on vehicle energy consumption. These models are applied over a wide array of real-world usage profiles and typical meteorological data to develop estimates of in-use fuel economy. The paper concludes with a discussion of how this integrated testing/modeling approach may be applied to quantify real-world, off-cycle fuel economy benefits of various technologies.

Fuel consumption effects of a diesel hybrid electric vehicle across a range of driving styles and ambient conditions

Reducing fuel consumption and thus greenhouse gas emissions is a major challenge for the automotive industry. To help achieve this goal, Diesel combustion engines as well as hybrid architectures are often used to further improve vehicle fuel efficiency. Combining these two technologies, the Peugeot 3008 Hybrid 4 was the first production vehicle utilizing a Diesel engine in a full hybrid powertrain with significant electric operating capability. This paper briefly introduces this vehicles hybrid topology and provides analysis regarding vehicle fuel consumption and operation over a large panel of drive cycles as well as hot (35°C) and cold (-7°C) ambient conditions.

PHEV Energy Management Strategies at cold temperatures with Battery temperature rise and Engine efficiency Improvement considerations

Limited battery power and poor engine efficiency at cold temperature results in low plug in hybrid vehicle (PHEV) fuel economy and high emissions. Quick rise of battery temperature is not only important to mitigate lithium plating and thus preserve battery life, but also to increase the battery power limits so as to fully achieve fuel economy savings expected from a PHEV. Likewise, it is also important to raise the engine temperature so as to improve engine efficiency (therefore vehicle fuel economy) and to reduce emissions. One method of increasing the temperature of either component is to maximize their usage at cold temperatures thus increasing cumulative heat generating losses. Since both components supply energy to meet road load demand, maximizing the usage of one component would necessarily mean low usage and slow temperature rise of the other component. Thus, a natural trade-off exists between battery and engine warm-up. This paper compares energy management strategies for a power-split PHEV for their ability to warm –up the battery and the engine, and ultimately the resulting fuel economy. The engine model predicts engine fuel rate as a function of engine utilization history and starting temperature, apart from speed and torque. The battery temperature rise model is a function of battery utilization. Engine and battery utilization is varied by changing the control parameter - wheel power demand at which the engine turns ON. The paper analyses the sensitivity of fuel and electrical energy consumption to engine and battery temperature rise, for different driving distances and driver aggressivenes

On-Road Validation of a Simplified Model for Estimating Real-World Fuel Economy

On-road fuel economy is known to vary significantly between individual trips in real-world driving conditions. This work introduces a methodology for rapidly simulating a specific vehicle’s fuel economy over the wide range of real-world conditions experienced across the country. On-road test data collected using a highly instrumented vehicle is used to refine and validate this modeling approach. Model accuracy relative to on-road data collection is relevant to the estimation of “off-cycle credits” that compensate for real-world fuel economy benefits that are not observed during certification testing on a chassis dynamometer.

The Effect of Spark Plug Electrode Geometry on Combustion Rates in a High Performance Automotive Engine

Spark plugs utilizing a J-wire electrode are standard in most automotive engines and have been for decades. However, innumerable alternative spark plug designs have been introduced. This paper examines the potential benefit of one particular alternative electrode geometry in a high-performance automotive engine. The alternative spark plug that is investigated is a commercially available aftermarket unit. The testing included detailed analysis of both brake and indicated parameters including MEP and burn rates. Testing was conducted under both steady state and transient conditions, and encompassed multiple induction systems and test fuels including E85. The test engine was a commercially available high performance aftermarket engine assembly intended for motorsports.This paper includes the optimal settings for ignition timing and lambda and the process by which those values were determined. The combustion analysis shows the alternative spark plug electrode resulted in an increased early burn rate, which in turn lead to an overall advancing of the combustion phasing. To better decouple combustion phasing effects from test to test variation on brake output parameters, an empirical model is developed and exercised. The model describes the expected change in brake output resulting from the shift in combustion phasing induced by the alternative spark plug geometry.Copyright