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Journal Article

Medium-Duty Plug-in Hybrid Electric Vehicle for Utility Fleets

Current concerns about climate change, energy security and record high oil prices have triggered high enthusiasm and push for plug-in vehicles. Widespread adoption of plug-in vehicles would result in significant reductions in CO2 emissions from transportation. It would also reduce our dependence on fossil fuels by replacing petroleum-sourced energy with renewable, domestically produced electricity. While a few OEMs have successfully launched hybrid vehicles and even toyed with plug-in hybrid solutions in the passenger car market segment, little attention has been placed on heavier commercial vehicles. Large utilities operate fleets of several hundred diesel-power trouble trucks to repair and maintain their transmission and distribution infrastructure. Medium-duty segment is over a million vehicles annually. These vehicles are typically driven in densely populated neighborhoods.
Technical Paper

A Driver Assistance System for Improving Commercial Vehicle Fuel Economy

Commercial vehicle operators and governments around the world are looking for ways to cut down on fuel consumption for economic and environmental reasons. Two main factors affecting the fuel consumption of a vehicle are the drive route and the driver behavior. The drive route can be specified by information such as speed limit, road grade, road curvature, traffic etc. The driver behavior, on the other hand, is difficult to classify and can be responsible for as much as 35% variation in fuel consumption. In this work, nearly 600,000 miles of drive data is utilized to identify driving behaviors that significantly affect fuel consumption. Based on this analysis, driving scenarios and related driver behaviors are identified that result in the most efficient vehicle operation. A driver assistance system is presented in this paper that assists the driver in driving more efficiently by issuing scenario specific advice.
Technical Paper

Diesel Fan Drives, Do They Save Fuel?

A method for measuring diesel fuel consumption accurately over short distances of 5 miles or less was developed so that many fan-on, fan-off data sets could be gathered in a short time for statistical evaluation and analysis. A second test sequence involved fan-on, fan-off fuel economy tests over a highway route for comparison against the Cummins Vehicle Mission Simulation Computer Program. The predicted results from this program agreed substantially with the actual highway economy test data we obtained. More than 4 million charted miles of roads throughout the world are available through this program for predicting fan-off fuel savings. Results on several typical routes are given.
Technical Paper

Switching Response Optimization for Cylinder Deactivation with Type II Passenger Car Applications

An advanced Variable Valve Actuation (VVA) system is optimized for response time in order to provide robust switching at high engine speeds. The VVA system considered is Cylinder Deactivation (CDA) for the purpose of improving fuel economy. Specifically, a Switching Roller Finger Follower (SRFF) on a Dual Overhead Camshaft (DOHC) engine is optimized for cylinder deactivation. The objective of this work is to (1) improve the latch response time when the system response is the slowest, and (2) balance the “ON” and “OFF” response time. A proper tradeoff was established to provide the minimum switching time such that deactivation and reactivation occurs seamlessly and in the right sequence. The response time optimization is accomplished while maintaining the existing packaging space of the overhead. A camshaft with a single lobe per SRFF device on a type II valvetrain was used as the baseline configuration for this study.
Technical Paper

Development of a Switching Roller Finger Follower for Cylinder Deactivation in Gasoline Engine Applications

A cylinder deactivation system has been developed for use on dual overhead camshaft (DOHC), roller finger follower valvetrain engine applications. Cylinder deactivation is emerging as an effective means to reduce fuel consumption in vehicles, especially those equipped with V6 or V8 engines. This paper addresses a new system that accomplishes this function through the use of a switching roller finger follower (SRFF). This system includes key design features that allow application of the SRFF without affecting overall width, height, or length of DOHC engines. Emphasis was placed on reducing the moment of inertia over the SRFF pivot without compromising rocker arm stiffness. The switching mechanism for transitioning between normal and deactivated operation is hydraulically actuated with engine oil. The switching windows are identified in terms of temperature, pressure, and engine speed. High engine speed test results show stable valvetrain dynamics above 7000 rpm engine speed.
Technical Paper

Part-Task Simulator for Truck Transmission Gear Shifting

A part-task simulator has been developed which concentrates on the functions related to transmission gear shifting in heavy duty trucks. By avoiding the complexity of full-feature simulators, a simple and cost-effective tool has been produced which allows training of the driver and study of the powertrain in a controlled environment. The components and operation of this new simulator are described, along with present and potential applications.
Technical Paper

Automated Mechanical Transmissions

Eaton has been working on technologies for cost effective, reliable and safe Automated Mechanical Transmissions (AMTs) since the mid 1970's. The company has introduced three different systems since the late 1980's, but all three systems were constrained by the lack of precise engine speed control during shifting. With the advent of electronic engine controls the constraint has been removed and precise engine speed control during shifting can be easily accomplished. The result is a simplified system that is powerfully intelligent and fully capable of automatic shifting i.e., the transmission system determines when to shift and executes the shift without any driver inducement across the broad spectrum of truck usage. This paper discusses some of the AMTs available to the truck market, showing how the system benefits both the OEM and the end user.
Technical Paper

NVH Development of Digital Hydraulics System for Off-Highway Vehicle Applications

Fuel economy of both highway and off-highway vehicles is a major driver for new technology development. One of the technologies to meet this driver is a digital valve based hydraulic system. Digital Hydraulics technology employs high speed on/off valves to achieve the same functionality with no throttling loss. Furthermore, by forming various architecture by using digital valves, it provides the system level capability and flexibility for energy saving and productivity improvement. There are many challenges in fully realizing the full efficiency benefits of the system in an actual application. These challenges include packaging, durability, a change in the operator's perception of the vehicle as well as hydraulic system performances during operation. One significant issue is the noise, vibration and harshness (NVH) of the system. Due to the nature of the digital valve operation, there are severe transient dynamics in the fluid system.
Journal Article

Genetic Algorithm Based Gear Shift Optimization for Electric Vehicles

In this paper, an optimization method is proposed to improve the efficiency of a transmission equipped electric vehicle (EV) by optimizing gear shift strategy. The idea behind using a transmission for EV is to downsize the motor size and decrease overall energy consumption. The efficiency of an electric motor varies with its operating region (speed/torque) and this plays a crucial role in deciding overall energy consumption of EVs. A lot of work has been done to optimize gear shift strategy of internal combustion engines (ICE) based automatic transmission (AT), and automatic-manual transmissions (AMT), but for EVs this is still a new area. In case of EVs, we have an advantage of regeneration which makes it different from the ICE based vehicles. In order to maximize the efficiency, a heuristic search based algorithm - Genetic Algorithm (GA) is used.
Journal Article

Model-Based and Signal-Based Gearbox Sensor Fault Detection, Identification and Accommodation

The emergence of tougher environmental legislations and ever increasing demand for increased ride comfort, fuel efficiency, and low emissions have triggered exploration and advances towards more efficient vehicle gearbox technologies. The growing complexity and spatial distribution of such a mechatronic gearbox demands precise timing and coordination of the embedded electronics, integrated sensors and actuators as well as excellent overall reliability. The increased gearbox distributed systems have seen an increased dependence on sensors for feedback control, predominantly relying on hardware redundancy for faults diagnosis. However, the conventional hardware redundancy has disadvantages due to increased costs, weight, volume, power requirements and failure rates. This paper presents a virtual position sensor-based Fault Detection, Isolation and Accommodation (FDIA), which generates an analytical redundancy for comparison against the actual sensor output.
Technical Paper

Application of Simulation Based Methods in Development of Wet Clutch System

The increased trend of automatic and automated transmissions across a breadth of applications is one of the market drivers for the development of wet clutch systems. Key product differentiators that drive the use of wet clutches in specific applications are (a) Compactness, (b) Low inertia, (c) Higher energy density, (d) Better NVH characteristics, and (e) Longer wear life. The above-stated product differentiators are dependent on performance of both the clutch cooling system and the friction system for two different operating events, namely engagement and disengagement. During engagement, slip under load between the clutch plates generates heat, which must be carried away by the oil, necessitating a high oil flow demand to all friction surfaces. Failing to achieve this leads to excessive plate temperatures and wear, ultimately resulting in poor performance and reduced clutch life.
Technical Paper

Development of CFD Methodology for Drag Force Prediction on Passenger Car with Rear Mounted Spoiler

Eaton has supported the design and development of spoilers for automobile applications. Addition of spoilers in the car influences the external aerodynamics and in turn impacts fuel economy and vehicle stability, in addition to providing improved external aesthetics. With the upward trend in fuel prices, it becomes more critical to quantify the effect of spoiler on the fuel economy. Eaton Corporation has undertaken efforts to establish predictive capability for evaluating the effect of a rear mounted spoiler on fuel economy. A first phase of these efforts focuses on development of a CFD methodology on the Ahmed Reference model and validation with wind tunnel testing. A second phase will focus on leveraging the methodology on an actual automobile and in the last phase, fuel economy models will be built using outputs from the CFD methodology. This paper focuses on detailed discussion about first phase of the work and summary of the second phase.
Technical Paper

Electronic Thermostat System for Automotive Engines

The paper suggests the benefits to be gained from using an electronic thermostat to improve control over the coolant temperature of an operating gasoline engine. It also describes the work undertaken to confirm that engine temperature can be maintained at a selected level and that the temperature level can be raised or lowered as desired in a running vehicle. The common automotive mechanical thermostat has the limitation of a fixed operating point with coolant flow rate dependent on temperature rise. Over its long life it has been refined economically to the point where the advantages of a more sophisticated device, made possible with electronics, have not been explored in depth. Recent electronic advances, however, make possible the addition of features that should justify the economic differential. The advantages and features that can be obtained with an electronic thermostat will be presented along with design considerations and test results.
Technical Paper

Diesel Engine Cylinder Deactivation for Improved System Performance over Transient Real-World Drive Cycles

Effective control of exhaust emissions from modern diesel engines requires the use of aftertreatment systems. Elevated aftertreatment component temperatures are required for engine-out emissions reductions to acceptable tailpipe limits. Maintaining elevated aftertreatment components temperatures is particularly problematic during prolonged low speed, low load operation of the engine (i.e. idle, creep, stop and go traffic), on account of low engine-outlet temperatures during these operating conditions. Conventional techniques to achieve elevated aftertreatment component temperatures include delayed fuel injections and over-squeezing the turbocharger, both of which result in a significant fuel consumption penalty. Cylinder deactivation (CDA) has been studied as a candidate strategy to maintain favorable aftertreatment temperatures, in a fuel efficient manner, via reduced airflow through the engine.
Technical Paper

Comparative Studies of Drivetrain Systems for Electric Vehicles

Vehicle electrification is being actively expanded into coming generations of passenger and commercial vehicles. This technology trend is helping vehicles to become more energy efficient. For electric vehicle (EV) city bus application, the system designers have been experimenting with a number of options including direct drive and multi-speed gearbox architectures. Direct drive scenario offers simplified drivetrain system, however requires a large and powerful electric motor. Multi-speed transmission system provides an opportunity to reduce motor size and optimize its operating points, but increases complexity from the architecture and controls point of view. This paper provides an overview of several common system layouts and examines their advantages and disadvantages. Vehicle simulation results are presented to compare direct drive vs. multi-speed technology from the gradeability, acceleration and energy consumption points of view.
Technical Paper

Downspeeding a Light Duty Diesel Passenger Car with a Combined Supercharger and Turbocharger Boosting System to Improve Vehicle Drive Cycle Fuel Economy

Downsizing and downspeeding have become accepted strategies to reduce fuel consumption and criteria pollutants for automotive engines. Engine boosting is required to increase specific power density in order to retain acceptable vehicle performance. Single-stage boosting has been sufficient for previous requirements, but as customers and governments mandate lower fuel consumption and reduced emissions, two-stage boosting will be required for downsized and downsped engines in order to maintain performance feel for common class B, C, and D vehicles. A 1.6L-I4 diesel engine model was created, and three different two-stage boosting systems were explored through engine and vehicle level simulation to reflect the industry's current view of the limit of downsizing without degrading combustion efficiency with cylinder volumes below 400 cm₃. Some current engines are already at this size, so downspeeding will become much more important for reducing fuel consumption in the future.

Advanced Hybrid Powertrains for Commercial Vehicles

This book provides a broad and comprehensive look at hybrid powertrain technologies for commercial vehicles. It begins with the fundamentals of hybrid powertrain systems, government regulations, and driving cycles, then provides design guidelines and key components of hybrid powertrains for commercial vehicles. It was written for vehicle and component engineers and developers, researchers, students, policymakers, and business executives in the commercial vehicle and transportation industries to help them understand the fundamentals of hybrid powertrain technologies and market requirements for commercial vehicles. It is useful for anyone who designs or is interested in hybrid powertrains and their key components. The term ‘commercial vehicle’ applies to everything from light delivery vehicles to class 8 long haul trucks, buses, and coaches. These vehicles are used for a wide range of duties, including transporting goods or people and infrastructure service.