Review of the Research Program of the Partnership for a New Generation of Vehicles Sixth Report (2000) / Chapter Skim
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2. Development of Vehicle Subsystems
2. Development of Vehicle Subsystems
Pages 18-55
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From page 18... ...
In addition to improving the energy-conversion efficiency of the power train (including energy converters and transmissions) and reducing other energy losses in the vehicle, achieving the Goal 3 fuel economy objective will require a very large weight reduction (> 40 percent)
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From page 19... ...
INTERNAL COMBUSTION RECIPROCATING ENGINES The internal combustion engine continues to be the primary candidate power plant for meeting near-term PNGV program goals. To meet the fuel economy target of Goal 3, the internal combustion engine will have to be integrated into an HEV configuration.
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From page 20... ...
In addition to proprietary internal work on the concept vehicles, PNGV continued its collaborative programs on precompetitive fundamental technologies, including interactions between fuel composition and engine performance (as recommended in the committee's fifth review [NRC, 19991~; the fundamentals of combustion, including some very novel concepts; and in response to Tier 2 emission standards, a stepped-up investigation of emission control technologies and sensors. Progress to date and the future plans of the 4SDI technical team are discussed below in three sections: engine-fuel interactions; engine-combustion system developments; and after-treatment and controls and sensors.
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From page 22... ...
As the committee has noted in previous reports, the PNGV technical team has determined that none of the 4SDI technologies will be capable of meeting the emission standards without extensive exhaust-gas after-treatment (NRC, 1998, 1999~. Therefore, determining the effects of fuel properties, especially sulfur content, on the conversion efficiency of the after-treatment devices will be critical.
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From page 23... ...
The desirable engine attributes described above are inherent characteristics of diesel engines, the most efficient internal combustion engines available. For this reason, as well as because extensive manufacturing and operating experience are available, the diesel engine is the engine of choice as the principal energy converter for the PNGV program.
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From page 24... ...
The initial design targets for NOX and PM emissions at the start of the PNGV program were 0.2 g/mile NOX and 0.04 g/mile PM. These targets seemed to be attainable with an advanced technology diesel engine and some exhaust-gas after-treatment.
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From page 25... ...
Prior to the announcement, PNGV believed that the best chance of reaching 80 mpg in its time frame was with a diesel engine as the primary energy converter. Based on the current assessment, the challenges of meeting the Tier 2 emission standards with the diesel engine will be enormous, and the technology most likely to meet the new standards is an engine that uses homogeneous stoichiometric combustion, for which the exhaustgas after-treatment is most advanced.
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From page 26... ...
A special fuel system using dimethyl ether was successfully constructed and tested, and more extensive testing of this interesting fuel can now be done in a Ford DIATA (direct-injection, aluminum-block, through-bolt assembly) diesel engine.
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From page 27... ...
The estimate of funding for collaborative research on emission control for PNGVsized CIDI engines for 1999 was $52 million. After-Treatment and Controls and Sensors Meeting the new EPA Tier 2 emission standards will be a major challenge for any internal combustion engine, especially the diesel engine.
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From page 28... ...
There were significant differences in the conversion efficiencies of the catalyst for the two engines. For the VW engine, the conversion efficiency was less than one-half of the conversion efficiency for the Navistar engine.
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From page 29... ...
Issues of Concern The 4SDI technical team has made excellent progress. Nevertheless, in the short term at least, the more stringent emission standards bring into question the viability of the most efficient power plant as a primary energy converter for the PNGV vehicle.
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From page 30... ...
As PNGV continues its development activities, it will be critical to quantify and compare the fuel economy penalties associated with engine systems that are projected to meet the emission standards. An effective method to accomplish this would be to use the systems models to predict the optimal power train configuration for each engine type and after-treatment system that would meet the emission standards.
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From page 31... ...
However, because of the longer time scale, fuel cells were not considered for the "deliverable" PNGV concept cars introduced in 2000, for which the much more mature CIDI engine was selected by all three automakers as the near-term energy converter of choice. In fact, the CIDI engine in an HEV configuration was projected to yield average energy conversion efficiencies almost as high as those of hydrocarbon-fueled fuel cell vehicles, while meeting (albeit with some difficulty)
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From page 32... ...
However, from the standpoint of the fuel cell energy converter, it presents the greatest challenges because it requires a high-temperature fuel processor with extensive carbon monoxide (CO) "cleanup," which leads to start-up and transient delays, as well as significant efficiency losses.
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From page 33... ...
Also, steady-state emission levels were far below EPA Tier 2 standards. However, the start-up time for the fuel processor from ambient temperature was about seven minutes, the test processor was not an "integrated" system, and the stack and fuel processor were operated separately.
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From page 34... ...
New research facilities are being dedicated at IFC to PEM stack development, as well as fuel processing for hydrogen, methanol, and petroleum-based hydrocarbon fuels. Another impressive industrial fuel cell development project is under way at the GM Global Alternative Propulsion Center (GAPC)
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From page 35... ...
The results of their efforts have revived interest in steam reforming, which is more efficient than alternative reformer concepts but was believed to be incompatible with automotive applications because of limited heat transfer rates. Results to date appear to confirm the potential for dramatic reductions in fuel processor size and to show fuel conversions (with iso-octane)
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From page 36... ...
The noble-metal requirement for the fuel cell stack, based on current technology, is more than an order of magnitude greater than for current automobile catalytic converters. If noble metal is also used in the fuel processor, substantially more would be required.
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From page 37... ...
Another concern is that projected demands for platinum (and other precious metals) could exceed the world supply if fuel cell vehicles eventually replace internal combustion engine vehicles.
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From page 38... ...
. In summary, fuel cells will remain very important to the PNGV programespecially as Tier 2 emission regulations are implemented.
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From page 39... ...
Also, the emissions and fuel economy with an internal combustion engine should be improved if the engine load varies over only a narrow range. Batteries designed for high specific power are the most likely means of energy storage.
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From page 40... ...
Hopes have been pinned on lithium or lithium-ion (Li-ion) batteries for high energy and energy efficiency, but NiMH batteries are still a less risky backup system for nearer term deployment in concept vehicles.
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From page 41... ...
Because the power/energy ratio is different for the two modes, a larger range of state-of-charge can perhaps be used in the dual mode; that is, the PNGV target "energy utilization factor," the ratio of available energy to rated energy, can be 0.378 for the dual mode as compared to 0.141 for the power-assist mode. However, the required specific power is still the same for the two applications.
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From page 42... ...
The automotive companies have made their own arrangements with battery suppliers for systems in their concept vehicles, which enables them to use systems analysis to coordinate the battery technology requirements and performance with other parts of the vehicle in a proprietary setting. As a consequence, the PNGV program should focus on generic issues, such as producing systems with good performance and dealing with issues of life, cost, and safety, as well as control of series strings and thermal management.
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From page 43... ...
process in 1997 resulted in all three USCAR partners adopting an HEV configuration for their PNGV vehicles. The cost, volume, complexity, and weight of the electrical and electronic systems in an HEV are substantially greater than in a conventional, nonhybrid car powered by an internal combustion engine.
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From page 44... ...
The power electronics component of the program includes the development of an automotive integrated power module (AIPM) , the development of new thermal management techniques and materials, and the investigation of new materials and manufacturing processes for passive energy-storage components, particularly capacitors.
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From page 45... ...
However, given the importance of the electrical and electronic systems to the viability of the entire PNGV vehicle, the EE Tech Team must always be aware of progress toward cost goals and must communicate this information to the systems analysis team. In its fifth report, the committee recommended that the EE Tech Team perform an analysis of electrical accessory loads to verify system needs.
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From page 46... ...
Although the details of the accessory system will differ among the three USCAR partners, the impact of the accessory load is important enough that it should be considered explicitly by the systems analysis team. STRUCTURAL MATERIALS AND SAFETY The reduction of vehicle mass through improved design, lightweight materials, and new manufacturing techniques is one of the key strategic approaches to meeting the PNGV Goal 3 fuel economy target.
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From page 47... ...
All of these processes were integrated into a unified approach to reduce the average thickness of steel sheet and thereby save weight. At the end of the study, the ULSAB BIW weighed only 447 lbs, a 24-percent reduction over the PNGV baseline vehicle described in Table 2-3, and as much as 36 percent lower in weight than the heaviest PNGV vehicle benchmarked in the ULSAB study.
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From page 48... ...
and a total weight of 2,275 lbs [1,032 kg] when powered by a gasoline-fueled internal combustion engine)
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From page 49... ...
Proprietary crash modeling is being used extensively by the USCAR partners to develop crashworthy 2000 concept vehicles. The PNGV program, however, is exploring advanced crash modeling methods at ORNL by running modern crash models on high-speed, parallel computers to develop crashworthy structures of steel, aluminum, and composites, as well as hybrid-material structures (Simunovic and Carpenter, 1999~.
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From page 50... ...
The requirement that the overall cost of vehicle ownership not be increased presents a major hurdle to meeting the fuel economy goal. The road map reflects this requirement by defining reduction in the cost of feedstock as a common challenge for all alternative materials.
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From page 51... ...
These trends are expected to continue, although reinforced nylon composites, which provide a cost and weight savings, are replacing aluminum in many intake manifold applications. The PNGV materials road map describes major efforts to reduce the costs of feedstock and improve the casting processes for cast aluminum (PNGV, 1999a)
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From page 52... ...
In the PNGV concept vehicle phase, the emphasis has been on aluminum and composites to meet the 50-percent weight reduction target. As the PNGV program moves toward 2004 and the production of affordable production prototypes, the PNGV team should attempt to balance the opposing requirements of weight reduction and affordability.
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From page 53... ...
As a matter of public record, several aluminum-intensive prototype vehicles have been built outside the PNGV program by the USCAR partners and evaluated for ride, handling, noise, vibration, and handling, crashworthiness, and production processes, such as stamping, extruding, joining, and painting (Jewett, 1997~. The three PNGV concept cars are all different in this respect (Askari, 2000~.
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From page 54... ...
Although the weight savings are impressive, CFRP technology must be considered a long-term alternative to steel and aluminum. Power Train and Chassis System The committee was pleased to see that several important R&D studies are now in place to reduce the costs and improve the properties of aluminum and magnesium castings.
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From page 55... ...
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