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Efficiency testing of hybrid-electric vehicles is challenging, because small run-to-run differences in pedal application can change when the engine fires or the when the friction brakes supplement regenerative braking, dramatically affecting fuel use or energy regeneration. Electronic accelerator control has existed for years, thanks to the popularity of throttle-by-wire (TBW). Electronic braking control is less mature, since most vehicles don’t use brake-by-wire (BBW). Computer braking control on a chassis dynamometer typically uses a mechanical actuator (which may suffer backlash or misalignment) or braking the dynamometer rather than the vehicle (which doesn’t yield regeneration). The growth of electrification and autonomy provides the means to implement electronic brake control. Electrified vehicles use BBW to control the split between friction and regenerative braking. Automated features, e.g. adaptive cruise control, require BBW to actuate the brakes without pedal input.

The confluence of fuel economy improvement requirements and increased use of ethanol as a gasoline blend component has led to various studies into the efficiency and performance benefits to be had when using high octane number, high ethanol content fuels in modern engines. As part of a comprehensive study of the autoignition of fuels in both the CFR octane rating engine and a modern, direct injection, turbocharged spark ignited engine, a series of fuel blends were prepared with market relevant ranges of octane numbers and ethanol blends levels. The paper reports on the first part of this study where fuel flow measurements were done on a single cylinder research engine, utilizing a GM LHU combustion system, and then used to predict drive cycle fuel economy. For a range of engine speeds and manifold air pressures, spark timing was adjusted to achieve either the maximum brake torque (MBT) or a matched 50 % mass fraction burnt location.

Southwest Research Institute developed an Autonomous Ground Vehicle (AGV) capable of navigating in urban environments. The paper first gives an overview of hardware and software onboard the vehicle. The systems onboard are classified into perception, intelligence, and command and control modules to mimic a human driver. Perception deals with sensing from the world and translating it into situation awareness. This awareness is then fed into intelligence modules. Intelligence modules take inputs from the user to understand the need to navigate from its current location to another destination and, then, generate a path between them on urban, drivable surfaces using its internal urban database. Situational awareness helps intelligence to update the path in real time by avoiding any static/moving obstacles while following traffic rules.

An investigation was performed to identify the benefits of cooled exhaust gas recirculation (EGR) when applied to a potential ethanol flexible fuelled vehicle (eFFV) engine. The fuels investigated in this study represented the range a flex-fuel engine may be exposed to in the United States; from 85% ethanol/gasoline blend (E85) to regular gasoline. The test engine was a 2.0-L in-line 4 cylinder that was turbocharged and port fuel injected (PFI). Ethanol blended fuels, including E85, have a higher octane rating and produce lower exhaust temperatures compared to gasoline. EGR has also been shown to decrease engine knock tendency and decrease exhaust temperatures. A natural progression was to take advantage of the superior combustion characteristics of E85 (i.e. increase compression ratio), and then employ EGR to maintain performance with gasoline. When EGR alone could not provide the necessary knock margin, hydrogen (H2) was added to simulate an onboard fuel reformer.

Brake energy recovery is one of the key components in today's hybrid vehicles that allows for increased fuel economy. Typically, major engineering changes are required in the drivetrain to achieve these gains. The objective of this paper is to present a concept of capturing brake energy in a mild hybrid approach without any major modifications to the drivetrain or other vehicular systems. With fuel costs rising, the additional component cost incurred in the presented concept may be recovered quickly. In today's vehicles, alternators supply the electrical power for the engine and vehicle accessories whenever the engine is running. As vehicle electrical demands increase, this load is an ever-increasing part of the engine's output, negatively impacting fuel economy. By using a regenerative device (alternator) on the drive shaft (or any other part of the power train), electrical energy can be captured during braking.

This paper will describe the fuel economy benefits that can be obtained when traditionally engine-driven accessories such as water pumps, oil pumps, power steering pumps, radiator cooling fans and air conditioning compressors are decoupled from the engine and are remotely driven and controlled. Simulation results for different vehicle configurations such as heavy duty trucks operated over urban and highway driving cycles and light duty vehicles such as mini vans will be presented. These results will quantify the heavy dependence of fuel economy benefits associated with different types of driving cycles.

During city traffic or heavily congested roads, a vehicle can consume a substantial amount of fuel idling when the vehicle is stopped. Due to regulation enforcement, auto manufacturers are developing systems to increase the mileage and reduce emissions. Turning off the engine at traffic lights and regenerative braking systems are simple ways to reduce emissions and fuel consumption. In order to develop strong manufacturer and consumer interest, this type of operation needs to be automated such that the stop/start functionality requires no driver interaction and takes place without the intervention of the vehicle operator. Valeo Electrical Systems has developed such a system that replaces the OEM engine alternator with a starter/alternator driven by a standard multi-ribbed V belt. To avoid a break and dual voltage network, this system is based on a 12V electrical system using an Enhanced Power Supply.

A unique and attractive variator mechanism has been developed by Turbo Trac, Inc. and Southwest Research Institute (SwRI) for initial use in a heavy duty diesel truck application. High efficiency levels have been predicted with analytical models and confirmed with actual test data. Further, this variator incorporates a very stable and simple control system and has extremely high torque capacity. The prototype of the variator mechanism has also been configured with a modified Allison 650 series transmission for use as a series application in a Peterbilt truck, the final configuration will be a split power design. The setup includes a preliminary control system that allows for highway driving. It is emphasized, however, that Allison did not contribute to this design or any of the content of this paper.

Automotive catalytic converters must provide a very high level of mechanical and thermal durability to maintain performance during their 100,000 to 150,000 mile life expectancy. The work reported herein characterizes the converter as a base (can) excited spring (mat material) supported mass (substrate). A mat material coupon test apparatus was developed for the purpose of providing parameter data for the converter model in the form of stiffness and material loss factor data as a function of shear deflection across the mat. An intumescent mat material was chosen and its dynamic properties evaluated for a range of converter operating parameters. The mat material response properties were placed into a mat material database as a function of gap bulk density, substrate temperature, and temperature gradient across the mat.

In off-highway applications the engine torque is distributed between the transmission (propulsion) and other accessories such as power steering, air conditioning and implements. Electronic controls offer the opportunity to more efficiently manage the control of the engine and transmission as an integrated system. This paper deals with development of a steepest descent algorithm for maximizing the efficiency of hydrostatic transmission along with the engine in the presence of accessory load. The methodology is illustrated with an example. The strategy can be extended to the full hydro-mechanical configuration as required. Applications of this approach include adjusting for component wear and intelligent energy management between different accessories for possible size reduction of powertrain components. The potential benefits of this strategy are improved fuel efficiency and operator productivity.

An Automatic Tire Inflation System (ATIS) specifically designed for commercial use on trailer axles is currently being installed and utilized successfully by trucking companies, the military and owner/operators throughout the U.S. A need exists for an ATIS specifically designed for the drive axles of Class 8 over-the- road tractors. The addition of an ATIS for drive axles will expand automatic tire monitoring capability to all heavily loaded tires of the over-the-road truck/trailer rig. An ATIS for drive axles has been designed, fabricated and tested. Testing and evaluation of the prototype ATIS drive axle system indicates the system can be successfully installed on a typical tractor rig and operated for an extended period without problems. The testing included a 50,000 mile evaluation of the ATIS installed in a laboratory test fixture. The test fixture used stock axle parts and operated at 65 MPH. Environmental testing was conducted at temperatures ranging from -20 to +200 degrees F.

An Emergency Tire Inflation System (ETIS) designed for use on commercial trucks was evaluated and tested. The ETIS is provided in kit form and designed to be installed by a truck operator to provide emergency air to inflate a low or punctured tire on tractor drive axles. The ETIS will continue to supply air to the tire until the system pressure falls below a safe air pressure level. The system is designed to allow the rig to be driven 500 miles to a tire repair station or to a safe location where tire repair service is available. The installation kit (Figure 1), which can fit under a truck seat, includes all the necessary equipment to install the system on the most common drive axles. The ETIS supplies air to the under-inflated tire through a previously qualified1 Rotary Union design. The Rotary Union is attached to the axle flange of the drive axle by a threaded adapter and two adjustable links that allow the Rotary Union to be placed at the center of rotation of the axle.

An Automatic Tire Inflation System (ATIS), specifically designed for use on commercial long haul trailers underwent complete testing and evaluation in 1993/1994.1 Testing and evaluation included a field test of a prototype system and a controlled laboratory evaluation of the Rotary Union which is the only component subject to wear. The testing of the prototype system indicated that design improvements were necessary before the system could be installed in fleet operations. The design improvements were completed and field installation of production ATIS began. The design improvements were intended to improve overall system durability, decrease installation time, to have less effect on the axle structure than the original design, implement the use of SAE or DOT Approved pressure components and increase overall dependability of the system. ATIS systems have now been developed and tested for most domestic trailer axle configurations.

An Automatic Tire Inflation System (ATIS), specifically designed for use on commercial long haul trailers, requires modification of the axles to direct air to the tires. The ATIS requires a drilled hole through the axle tube for the installation of a pneumatic fitting. The trucking industry expressed concern about the modification and its impact upon the axle structure, and the general durability of the system over a long period. A three-phase test program was developed and conducted to satisfy the concerns of the industry.

Progress on the development of active suspension for improving mobility of rough terrain vehicles is being hindered by the potentially high energy requirements. A unique regenerative active suspension system has been conceived and is being developed to provide active suspension with very low energy requirements. Regenerative active suspension consists of multiple variable displacement pumps, each controlling flow to and from hydro-pneumatic struts to control a vehicle's low frequency body motions. When fluid is returned from a strut to a pump, energy is recovered or “regenerated” so that the total energy requirement is very low. This paper presents the results of a study showing the potential of the regenerative active suspension system to improve vehicle control and ride comfort of rough terrain vehicles enhancing mobility while requiring very little additional energy.

Active automotive suspension systems have been under development for a number of years with recent introductions of various versions. A suspension system can be considered “active” when an outside power source is used to alter its characteristics, and these systems can be placed into one of three (3) different categories: semi-active damping, fully active, and low frequency active. A regenerative pump concept can minimize the power requirement for the low frequency active system. It utilizes four (4) independent variable displacement pump/motor combinations on a common shaft to actuate each individual suspension unit. This paper overviews the system configuration, describes the power and energy-saving features of the system, and discusses possible pump configurations and control strategies.

Antilock brake systems for air braked vehicles have been growing in popularity in Great Britain and Europe and appear to be candidates for extensive use in the United States as well. Previous mandated use in the United States during the 1970's was not successful, in part because of reliability problems, and the National Highway Traffic Safety Administration (NHTSA) has decided that a thorough evaluation of air brake antilock systems is necessary prior to any decision about the appropriateness of future mandatory use in the United States. This paper describes the electronic data collection equipment and processing techniques which are being used in the NHTSA 200 truck evaluation project. Detailed maintenance histories for each truck are being recorded manually as a separate segment of the project. An average of 6 to 7 megabytes of data per week is being collected in the various cities in which fleets are operating test vehicles.

An experimental program was designed to determine friction characteristics between brake pads and metal rotors that could indicate a brake fluid's propensity to cause chatter in wet-brakes. Friction was measured on a bench version of the John Deere wet-brake qualification system. Rotor and pad supports were made very rigid to avoid chatter in the simulator. One type of pad was run on cast-iron and mild steel rotors using two reference oils, one giving unacceptable levels of chatter and the other giving acceptable levels as previously determined in full-scale tests on the Deere system. The outstanding discriminating characteristic was the drop in friction from breakaway of the pad from the rotor. The ratio of the initial drop in the friction coefficient between unacceptable and acceptable oils for all conditions of the testing ranged from 1.7 to 2.0

This paper summarizes the results of tests conducted with anesthetized animals that were exposed to a wide range of passenger inflatable restraint cushion forces for a variety of impact sled - simulated accident conditions. The test configurations and inflatable restraint system concepts were selected to produce a broad spectrum of injury types and severities to the major organs of the head, neck and torso of the animals. These data were needed to interpret the significance of the responses of an instrumented child dummy that was being used to evaluate child injury potential of the passenger inflatable restraint system being developed by General Motors Corporation. Injuries ranging from no injury to fatal were observed for the head, neck and abdomen regions. Thoracic injuries ranged from no injury to critical, survival uncertain.

Injuries produced by standard three point restraint systems with retractors will be compared between cadavers in laboratory simulated collisions at 30 mph barrier equivalent speed and lap and shoulder belted front seat occupants in real world frontal collisions of '73-'75 full sized cars. Tests conducted at SwRI with belted, unembalmed, fresh cadavers have resulted in extremely severe thoracic and cervical injuries, including multiple rib fractures, fractures of the sternum, clavicle and cervical vertebrae. On the other hand, injury data from a national accident investigation study to evaluate the effectiveness of restraints in late model passenger cars indicates that such injuries in real world crashes of equivalent severity are not always observed. The reasons possible for these differences are discussed. Both programs at SwRI are funded by the National Highway Traffic Safety Administration.