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Technical Paper

Influences on Energy Savings of Heavy Trucks Using Cooperative Adaptive Cruise Control

An integrated adaptive cruise control (ACC) and cooperative ACC (CACC) was implemented and tested on three heavy-duty tractor-trailer trucks on a closed test track. The first truck was always in ACC mode, and the followers were in CACC mode using wireless vehicle-vehicle communication to augment their radar sensor data to enable safe and accurate vehicle following at short gaps. The fuel consumption for each truck in the CACC string was measured using the SAE J1321 procedure while travelling at 65 mph and loaded to a gross weight of 65,000 lb, demonstrating the effects of: inter-vehicle gaps (ranging from 3.0 s or 87 m to 0.14 s or 4 m, covering a much wider range than previously reported tests), cut-in and cut-out maneuvers by other vehicles, speed variations, the use of mismatched vehicles (standard trailers mixed with aerodynamic trailers with boat tails and side skirts), and the presence of a passenger vehicle ahead of the platoon.
Technical Paper

Fuel Consumption Tests for Evaluating the Accuracy and Precision of Truck Engine Electronic Control Modules to Capture Fuel Data

Many trucking fleets and organizations are extensively using truck onboard computers (OBC) to gather fuel consumption data from truck engines' Electronic Control Modules (ECM). This study aimed to assess the accuracy and the precision of truck engine control module concerning the fuel consumption data. The testing methodology evaluated the fuel consumption data provided by the ECM using test track and road fuel consumption tests, short-term operational observation, long-term operational observation and engine dynamometer tests. ECM data were retrieved using either onboard computers (OBC) or engine scan tools. Test track and road tests were mainly intended to evaluate the precision of ECM data for short distances, between 60 and 100 km. More than 220 test runs totalizing 22,000 km were conducted using 23 test vehicles.
Technical Paper

Track-test Evaluation of Aerodynamic Drag Reducing Measures for Class 8 Tractor-Trailers

Air resistance, after gross vehicle weight, is the largest factor responsible for vehicle energy loss and has an important influence on fuel consumption. The magnitude of aerodynamic drag is affected by the vehicle's shape, frontal area, and travel speed. This study aimed to evaluate several aerodynamic drag reduction measures applicable to class 8 tractor-trailer combinations. The tested aerodynamic devices included trailer aft body rear deflectors (boat tails), trailer skirts, gap deflectors, fuel tank fairings and truck rear-axle fenders. It also assessed the aerodynamic influence of opened doors on an empty wood chip van trailer on the fuel consumption of the tractor-trailer combination. The tests were conducted according to SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II.
Technical Paper

Evaluation of Class 7 Diesel-Electric Hybrid Trucks

The objectives of this project were to evaluate the reduction in fuel consumption and greenhouse gas (GHG) emissions made possible by hybrid technology, and to identify good driving habits with this type of vehicle. Two diesel-electric hybrid pick-up and delivery trucks and one diesel-electric hybrid utility vehicle equipped with an electric driven PTO (power take-off) system were included in the project. The first phase was the evaluation in actual operating conditions. Onboard computers were installed in the vehicles to record parameters that make it possible to determine driving habits. Based on operational data, specific duty cycles were built and track tests were conducted to measure the fuel consumption on these duty cycles. It was therefore possible to compare the hybrid trucks with other diesel trucks featuring similar characteristics. The delivery hybrid trucks showed up to 34% fuel savings during the track tests.
Technical Paper

Performance Evaluation of Heavy-Duty Vehicles Equipped with Automatic Transmissions and Powertrain Adaptive Systems in Forestry Transportation

The purpose of this study was to evaluate automatic transmissions in a forestry context by comparing their performance with that of standard manual transmissions, and assessing the possibility of improving fuel efficiency by adapting the engine and automatic transmission performances to the vehicle's load. Long-haul test results showed that during the test day, the degradation in driver performance with the manual transmission truck translated into a 2.9% relative increase in fuel consumption when compared with the automatic transmission truck. The fleet data assessment indicated no obvious difference in fuel consumption between the performance of automatic transmissions and manual transmissions. One system for adapting engine performance to vehicle load uses an onboard weigh scale to determine the load status of the vehicle.
Journal Article

Evaluation of the Influence of Stakes on Drag and Fuel Consumption for a Tractor-Logging Trailer Combination

The main objective of this study is to reduce the aerodynamic drag of tractor-trailer combinations used in the forest industry. In most cases, logging trucks on their return trips are usually travelling in unloaded conditions with upright stakes, which add drag. CFD and wind tunnel testing suggested a drag reduction of up to 35% with no upright stakes, which corresponds to 17% in fuel savings in unloaded conditions. One of the proposed fuel reduction concepts was therefore to have foldable stakes so that the stakes could fold down into a horizontal position while travelling in unloaded conditions. Fuel savings of 15% for a vehicle with stakes in the horizontal position were confirmed with track testing when compared to the fuel consumption of a vehicle with stakes in the vertical position. The coastdown test indicated 28% reduction in drag. The difference in drag reduction between the coastdown test and initial simulation was due to stake size and profile.