Technologies and Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles (2010) / Chapter Skim
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8 Approaches to Fuel Economy and Regulations
8 Approaches to Fuel Economy and Regulations
Pages 179-196
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From page 179... ...
, and test cycle (federal test procedure) were adopted by NHTSA for The purpose and structure of a regulatory program should its new fuel economy program.
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From page 180... ...
The tires, on both the tractor and the trailer, ing, considering the huge jump in weight hauling capacity will influence the rolling resistance. In addition, weight and between Class 8 (in excess of 130,000 lb)
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From page 181... ...
While van trailers present a trucks to achieve less stringent regulatory standards. Related convenient and predictable space envelope for aerodynamic to "reclassification" is a potential for change in market beevaluation, other trailers such as flat-decks have no such havior to avoid higher prices due to regulation (i.e., if Class fixed outer shell, and therefore the shape of flat deck trailers 2b is regulated but not Class 3 then buyers might buy more will change with each load transported, which in turn influ- of the larger Class 3 trucks because they would become less ences aerodynamic drag and thus fuel consumption.
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From page 182... ...
Arguably there is a fourth notable category of energy consumption-auxiliaries, that be considered, but is not as clearly separable. Vehicle chassis REGULATED PARTIES represents a structure that simply connects the body and There are at least two principal considerations to be evalu- the power train, and may be regarded as part of the power ated when seeking to determine the most effective point of train or part of the body for testing purposes.
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From page 183... ...
by improving the efficiency of the vehicle (power train, tires, • The metrics should incentivize subcomponent and total aerodynamics, etc.) , the vehicle can move a given amount vehicle development.
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From page 184... ...
The fol- improvements on vehicle types within the retooling cycle. lowing example illustrates practical considerations that will The challenge with a corporate average standard is that the be necessary when developing a fuel consumption regulatory medium- and heavy-duty vehicle market is extremely diverse instrument.
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From page 185... ...
• Best for high-speed steady-state test cycles • Cannot incorporate changes in grade to test cycle • Affected by ambient conditions • Requires "reference truck" to reduce test-to-test variability Chassis Heavy-duty chassis • Well-developed procedure • Facilities are limited and expensive dynamometer dynamometer with data • Computerized drivers' aids ensure very good • Accuracy depends on accurate input data from from a coast-down test compliance with transient test cycles coast-down test track • Very good repeatability • Coast-down data not reliable • Inability to handle variable grade Engine test Engine dynamometer • Well-developed test • Accuracy depends on complexity of simulation plus vehicle Vehicle simulation model • Minimal additional burden model and "accuracy" of model inputs simulation • Lowest total cost to vehicle manufacturers • Development of vehicle-specific modeling modeling • Ability to run large number of vehicle test cycles parameters likely to require additional vehicle/ off a single engine test component testing (i.e., dynamic wind tunnel tests for aerodynamic drag, tire tests) Power train Engine dynamometer that • Builds on current practice of engine • New business model may be needed to integrate test plus will accommodate hybrid dynamometer tests engine and other power train components vehicle power train hardware and • Ability to accommodate many cycles and • Process development required for integration of simulation model/cycle control (CIL)
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From page 186... ...
Table 8-3 describes the four major widely used or power train test data with vehicle simulation models. test methods -- in-use testing, test track testing, chassis dy- Particularly in the case of hybrid vehicles, it will be imnamometer testing, and simulation modeling -- and identifies portant to have high-fidelity data for the fuel consumption the advantages and disadvantages of each approach.
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From page 187... ...
ensures that incentives are applied at the foundation of the Figure 8-4 shows an outline of how a power train test can major vehicle systems that influence fuel consumption. be combined with a vehicle simulation model to determine Given the high fuel consumption sensitivity of some methe fuel consumption of a vehicle.
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From page 188... ...
Measuring and documenting the performance of these reliable and accurate methods to determine tire rolling key components in a constant and transparent way will be resistance and vehicle aerodynamic drag coefficients, incorimportant for the final-stage manufacturer. NHTSA may poration of simulation modeling with hardware, integrating wish to require suppliers to provide information in standard- a hybrid drive train within the standard test cell, characterized form at the power train, aerodynamics and tire levels.
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From page 189... ...
A fundamental concern raised by the committee and those regulate the final-stage vehicle manufacturers since they have who testified during our public sessions was the tension be- the greatest control over the design of the vehicle and its tween the need to set a uniform test cycle for regulatory pur- major subsystems that affect fuel consumption. Component poses, and existing industry practices of seeking to minimize manufacturers will have to provide consistent component the fuel consumption of medium and heavy-duty vehicles performance data.
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From page 190... ...
A certification test method must be highly accurate, repeatable, and identical to the in-use compliance Recommendation 8-4. Simulation modeling should be used tests as is the case with current regulation of light-duty ve with component test data and additional tested inputs from hicles tested on a chassis dynamometer, and for heavy-duty power train tests, which could lower the cost and adminisengine emission standards tested on engine dynamometers.
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From page 191... ...
2009. Setting the Stage for Regulation of Heavy-Duty Vehicle Fuel Economy and GHG Emissions: Issues and Opportunities.
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From page 192... ...
This approach recognizes that many fuel physically in accordance with accepted test protocol. consumption improvements occur at the sub component Power train performance is determined physically level and provides a means of quantifying the performance either by attaching a power train to a dynamometer or of these components so that the final stage manufacturer will by operating a chassis or mule containing a power train have reliable performance data to determine vehicle fuel with wheels on the drive axle on a chassis dynamomconsumption.
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From page 193... ...
Experimentally, a power train A power train may be used with a variety of tires and test will provide whole vehicle fuel consumption data if the bodies in real vehicle applications, and may be configured power train test uses values for aerodynamic drag and for tire or optimized differently for each application, or configured rolling resistance which represent that vehicle. However, it is generically for use in several applications.
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From page 194... ...
This use the same power train may be simulated economically. means that actual fuel consumption may vary significantly For any particular power train configuration, the power as a function of ambient temperature, humidity, intake manitrain performance may be confirmed on two or three cycles fold temperature, coolant and oil temperatures, barometric using weight, aerodynamic drag and tire rolling resistance pressure, aftertreatment temperature, aftertreatment aging, suited to a reasonable vehicle type.
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From page 195... ...
A metric based on volume (gal/cargo ft3-mile) with the same GVW rating and the identical power train and would resolve this particular application.
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From page 196... ...
Figure 8-A-2 Identical GVW rated straight trucks for high an.eps bitmap
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