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Technical Paper

On-Track Measurement of Road Load Changes in Two Close-Following Vehicles: Methods and Results

2019-04-02
2019-01-0755
As emerging automated vehicle technology is making advances in safety and reliability, engineers are also exploring improvements in energy efficiency with this new paradigm. Powertrain efficiency receives due attention, but also impactful is finding ways to reduce driving losses in coordinated-driving scenarios. Efforts focused on simulation to quantify road load improvements require a sufficient amount of background validation work to support them. This study uses a practical approach to directly quantify road load changes by testing the coordinated driving of two vehicles on a test track at various speeds (64, 88, 113 km/h) and vehicle time gaps (0.3 to 1.3 s). Axle torque sensors were used to directly measure the load required to maintain steady-state speeds while following a lead vehicle at various gap distances.
Technical Paper

Performance and Efficiency Assessment of a Production CNG Vehicle Compared to Its Gasoline Counterpart

2014-10-13
2014-01-2694
Two modern light-duty passenger vehicles were selected for chassis dynamometer testing to evaluate differences in performance end efficiency resulting from CNG and gasoline combustion in a vehicle-based context. The vehicles were chosen to be as similar as possible apart from fuel type, sharing similar test weights and identical driveline configurations. Both vehicles were tested over several chassis dynamometer driving cycles, where it was found that the CNG vehicle exhibited 3-9% lower fuel economy than the gasoline-fueled subject. Performance tests were also conducted, where the CNG vehicle's lower tractive effort capability and longer acceleration times were consistent with the lower rated torque and power of its engine as compared to the gasoline model. The vehicles were also tested using quasi-steady-state chassis dynamometer techniques, wherein a series of engine operating points were studied.
Journal Article

Developing a Utility Factor for Battery Electric Vehicles

2013-04-08
2013-01-1474
As new advanced-technology vehicles are becoming more mainstream, analysts are studying their potential impact on petroleum use, carbon emissions, and smog emissions. Determining the potential impacts of widespread adoption requires testing and careful analysis. PHEVs possess unique operational characteristics that require evaluation in terms of actual in-use driving habits. SAE J2841, “Utility Factor Definitions for Plug-In Hybrid Electric Vehicles Using 2001 U.S. DOT National Household Travel Survey Data,” published by SAE in 2009 with a revision in 2010, is a guide to using DOT's National Household Travel Survey (NHTS) data to estimate the relative split between driving in charge-depleting (CD) mode and charge-sustaining (CS) mode for a particular PHEV with a given CD range. Without this method, direct comparisons of the merits of various vehicle designs (e.g., efficiency and battery size) cannot be made among PHEVs, or between PHEVs and other technologies.
Journal Article

Validating Volt PHEV Model with Dynamometer Test Data Using Autonomie

2013-04-08
2013-01-1458
The first commercially available Plug-In Hybrid Electric Vehicle (PHEV), the General Motors (GM) Volt, was introduced into the market in December 2010. The Volt's powertrain architecture provides four modes of operation, including two that are unique and maximize the Volt's efficiency and performance. The electric transaxle has been specially designed to enable patented operating modes both to improve the electric driving range when operating as a battery electric vehicle and to reduce fuel consumption when extending the range by operating with an internal combustion engine (ICE). However, details on the vehicle control strategy are not widely available because the supervisory control algorithm is proprietary. Since it is not possible to analyze the control without vehicle test data obtained from a well-designed Design-of-Experiment (DoE), a highly instrumented GM Volt, including thermal sensors, was tested at Argonne National Laboratory's Advanced Powertrain Research Facility (APRF).
Technical Paper

Evaluating the Effects of Restraint Systems on Four Wheel Drive Testing Methodologies: A Collaborative Effort between NVFEL and ANL

2009-04-20
2009-01-1522
Testing vehicles for emissions and fuel economy has traditionally been conducted with a single-axle chassis dynamometer. The 2006 SAE All Wheel Drive Symposium cited four wheel drive (4WD) and all wheel drive (AWD) sales as climbing from 20% toward 30% of a motor vehicle market share. With an increasing number of four wheel-drive vehicles being introduced to the market place, certification testing for emissions and fuel economy has been changed to allow both two wheel drive and four wheel drive testing [1]. As manufacturers plan to test these vehicles in this mode, test methods need to be developed to allow for these changes. This paper focuses on the tie down methods available for 4WD testing to determine possible effects of test methodologies on a traditional 4WD Vehicle and a hybrid vehicle.
Technical Paper

Electronic Particulate Matter Sensor – Mechanisms and Application in a Modern Light-Duty Diesel Vehicle

2009-04-20
2009-01-0647
An electronic particulate matter sensor (EPMS) developed at the University of Texas was used to characterize exhaust gases from a single-cylinder diesel engine and a light-duty diesel vehicle. Measurements were made during transient tip-in events with multiple sensor configurations in the single-cylinder engine. The sensor was operated in two modes: one with the electric field energized, and the other with no electric field present. In each mode, different characteristic signals were produced in response to a tip-in event, highlighting the two primary mechanisms of sensor operation. The sensor responded to both the natural charge of the particulate matter (PM) emitted from the engine, and was also found to create a signal by charging neutral particles. The characteristics of the two mechanisms of operation are discussed as well as their implications on the placement and operation of the sensor.
Technical Paper

Further Development of an Electronic Particulate Matter Sensor and Its Application to Diesel Engine Transients

2008-04-14
2008-01-1065
This paper presents the latest developments in the design and performance of an electronic particulate matter (PM) sensor developed at The University of Texas at Austin (UT) and suitable, with further development, for applications in active engine control of PM emissions. The sensor detects the carbonaceous mass component of PM in the exhaust and has a time-resolution less than 20 (ms), allowing PM levels to be quantified for engine transients. Sample measurements made with the sensor in the exhaust of a single-cylinder light duty diesel engine are presented for both steady-state and transient operations: a steady-state correlation with gravimetric filter measurements is presented, and the sensor response to rapid increases in PM emission during engine transients is shown for several different tip-in (momentary increases in fuel delivery) conditions.
Technical Paper

Direct Measurement of Powertrain Component Efficiencies for a Light-Duty Vehicle with a CVT Operating Over a Driving Cycle

2003-10-27
2003-01-3202
In order to determine the factors that affect fuel economy quantitatively, the power flows through the major powertrain components were measured during operation over transient cycles. The fuel consumption rate and torque and speed of the engine output and axle shafts were measured to assess the power flows in a vehicle with a CVT. The measured power flows were converted to energy loss for each component to get the efficiency. Tests were done at Phase 1 and Phase 3 of the FTP and for two different CVT shift modes. The measured energy distributions were compared with those from the ADVISOR simulation and to results from the PNGV study. For both the Hot 505 and the Cold 505, and for both shift modes, the major powertrain loss occurs in the engine, including or excluding standby losses. However, the efficiency of the drivetrain/transmission is important because it influences the efficiency of the engine.
Technical Paper

In-Situ Mapping and Analysis of the Toyota Prius HEV Engine

2000-08-21
2000-01-3096
The Prius is a major achievement by Toyota: it is the first mass-produced HEV with the first available HEV-optimized engine. Argonne National Laboratory's Advanced Powertrain Test Facility has been testing the Prius for model validation and technology performance and assessment. A significant part of the Prius test program is focused on testing and mapping the engine. A short-length torque sensor was installed in the powertrain in-situ. The torque sensor data allow insight into vehicle operational strategy, engine utilization, engine efficiency, and specific emissions. This paper describes the design and process necessary to install a torque sensor in a vehicle and shows the high-fidelity data measured during chassis dynamometer testing. The engine was found to have a maximum thermodynamic efficiency of 36.4%. Emissions and catalyst efficiency maps were also produced.
Technical Paper

Design Diversity of HEVs with Example Vehicles from HEV Competitions

1996-02-01
960736
Hybrid Electric Vehicles (HEVs) can be designed and operated to satisfy many different operational missions. The three most common HEV types differ with respect to component sizing and operational capabilities. However, HEV technology offers design opportunities beyond these three types. This paper presents a detailed HEV categorization process that can be used to describe unique HEV prototype designs entered in college and university-level HEV design competitions. We explored possible energy management strategies associated with designs that control the utilization of the two on-board energy sources and use the competition vehicles to illustrate various configurations and designs that affect the vehicle's capabilities. Experimental data is used to help describe the details of the power control strategies which determine how the engine and electric motor of HEV designs work together to provide motive power to the wheels.
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