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A seven-degrees-of-freedom model of an articulated recreational vehicle is described and used to determine the relative significance of parameters and of degrees of freedom that affect lateral stability. Thirty-five parameters are used to describe tire-road interactions, roll freedom, suspension systems, geometry, mass distribution, the hitch, the drawbar, and the forward speed. Critical speeds associated with different systems are calculated. Comparisons of these critical speeds lead to conclusions important to the design and safe operation of articulated recreational vehicles.

The steady-state turning behavior of vehicles pulling trailers is formulated in a simplified manner using the concept of a handling diagram. The formulation assumes small slip angles but admits a non-linear relationship between the slip angle and side force of the tires.

The effect on trailer stability of hitchpoint lateral stiffness and damping is examined by means of a simplified model. The model used in the stability analysis is a one degree of freedom nonholonomic dynamical system and yields a third order linear differential equation. Trailer stability criteria are developed, and stability charts are presented which depict the stability criteria in terms of nondimensional parameters. The analysis shows that increasing hitchpoint lateral stiffness does not improve trailer stability whereas increasing hitchpoint lateral damping is much more important to trailer stability. In addition, the importance of hitchpoint loading to trailer stability is shown.

The paper presents a fuel modulation attenuation model for single point closed-loop fuel metering systems. The model calculates the attenuation of a metered air-fuel perturbation and the time delay in the transport of the perturbed signal from the metering point through the engine to the exhaust system as functions of the modulation frequency, engine RPM, intake manifold vacuum, and exhaust gas recirculation. Results are shown for a V-8 engine with sine wave, triangular wave and square wave modulations. It is found that the attenuation for the triangular wave is the highest and that for the square wave is the smallest. It is also found that in general the attenuation increases with increasing modulation frequency and increasing EGR, but decreases with increasing RPM. The model can be extended to study the attenuation and transport delay of other engines and wave forms.

Recently, Taylor and Kane have drawn attention to the potentially destabilizing influence of drawbar flexibility on the stability of articulated vehicles. They assumed that roll freedom does not affect stability. Moncarz, however, used a model that did not include drawbar flexibility and concluded that roll has a significant influence. Two questions are addressed in this paper. How do roll steer and drawbar flexibility affect stability? Are these effects independent? Comparisons of the stability predictions from four different articulated vehicle models lead to the conclusions that both roll steer and drawbar flexibility can have significant effects on stability and that these effects are not independent.

The automotive industry is in the process of reducing vehicle weight to meet the Federal mandate for gas mileage. Lightweight sheet molding compound (SMC) can make a significant contribution. However, to be competitive with other improved lightweight materials, several changes in the standard compression molding process must take place. This paper will present the current work in sheet molding compound processes at General Motors Manufacturing Development. It covers the processes of programmable force velocity control, molded coating, and mold heat transfer analysis; and the concepts on compounding of SMC sheet and of a multi-station, high productivity compression molding line.

Advance in technology and the necessity for conservation of energy have forced the design engineer to look closer to plastic materials in order to save weight of cars. The situation in Europe, and in particular the chances for fiber glass reinforced polyester are explained in detail.

The overall suitability of various steels (strain-aging steels such as capped nitrogenized and rephosphorized steels, killed rephosphorized and microalloyed steels) for automobile body-panel applications is assessed by comparing their characteristics with the performance requirements (formability, weldability, paintability, etc.). The formability of the steel sheets is perhaps the most important requirement for body-panel applications. To minimize the loss of formability that occurs as strength is increased, steels having yield strengths of 40 to 50 ksi are considered the primary candidates for use in body panels. Of the different types of 40- to 50-ksi steels reviewed, the killed rephosphorized steels (especially a silicon-containing version) show the best combination of formability and weldability.

The advent of electronic control systems has enabled automobile manufacturers to consider a vast variety of fuel, ignition, and exhaust gas recirculation system calibrations. Given a control system providing satisfactory performance, it is important to determine the calibration of that system which minimizes fuel consumption while meeting emission control standards. The disadvantage function technique enables an engineer to determine such an optimal calibration through an iterative procedure, interacting with a computer program. This paper describes the technique, illustrates it by example, and compares it with well-known optimization methods.

Many studies have been launched to determine whether it is possible to achieve 0.4 gms/mile Nox. Most of those studies question or deny the ability to design and develop a system to reliably maintain 0.4 gms/mile Nox. This paper reviews the factors requiring consideration towards accomplishing that Nox objective and theoritizes a system which should properly accommodate these considerations. Actual performance data is then presented on a commercially manufacturable system that demonstrates conformance to the 0.4 Nox requirement without penalty to economy or driveability. Finally, considerations toward even superior performance are presented.

Previous investigations have shown that fuel economy gains are possible in vehicles with increased compression ratio engines that meet 1978 Federal emission standards using oxidizing converter-EGR emission control systems. There has been no incentive to raise compression ratios, however, since the vehicle gains are offset by energy losses in the refinery due to refining the higher octane unleaded fuel required by high compression ratio engines. This paper discusses the application of an electronic closed loop knock control system to a higher compression ratio engine to allow operation on 91 Research Octane Number fuel. Two cars with different compression ratios are compared with both oxidizing converter - EGR and 3-way oxidizing-reducing converter-EGR closed loop carburetor emission control systems.

Automotive electronic engine control systems require complex interactive software designs which must provide appropriate responses to a variety of engine conditions. Software design verification will help achieve a high level of confidence in the released product. Several approaches to software design verification are discussed. Each technique provides an additional degree of confidence with a corresponding level of effort. Primary attention is given to the time based stimulus generation, the real time performance measurements, time based tolerance generation, and data reduction of a real time software design verification test system. A recommendation for future software design verification system capabilities is made.

Thermal management studies of the Lithium-Aluminum/Metal Sulfide Battery demonstrate the need for a light weight, high thermal efficiency case for electric batteries. Calculations based upon the rectangular configured MK IA battery using vacuum-foil insulation, show that the heat loss rate goal of 400 watts can be met. Experimental studies directed at the determination of the reversible T▵S heating gave results that compared within 8% with theoretically derived values. Calculations based upon the 50-kWh MK II battery and a 10,000 miles driven/year show that by utilizing the thermal storage capacity of the system, essentially no additional energy is needed to keep the battery hot.

Report sums up performance data obtained on lead-acid batteries and accessories especially designed for electric road vehicles. Also encompasses special technologies such as central electrolyte refilling system, forced cooling and central venting. Further describes VARTA'S latest accomplishments for reduced maintenance and improvement in reliability. Another objective is exploitation of improved technologies for motive power batteries for applications such as fork lift trucks. Furthermore, it presents development stage of VARTA'S improved nickel-iron FENOX-battery.

Various types of lead-acid batteries have developed because of different market needs. The small, uncertain market for electric vehicles has been met by modifying traction-type or golf-car type lead-acid batteries. Recently, governmental stimulation of the market for passenger electric vehicles has resulted in the design and development of batteries to meet specific performance goals for electric vehicle propulsion. The approach which the Eltra Electric Vehicle Group/C&D-Prestolite has taken toward meeting the governmental goals involves the use of expanded metal, non-antimonial grids, overpasted plates, reduced electrolyte and an enveloped, glass mat retention system.

THE BATTERY is the primary component limiting electric vehicle performance that equals today's standard of expectations as defined by the I. C. engine powered vehicles. Efforts to optimize the electric vehicle performance is leading many people to select and assemble the highest efficiency components available. High voltage electric vehicle power system can provide performance advantages over lower voltage systems, but only if this voltage is in balance with the total system. Mixing high efficiency components does not Insure total system efficiency optimization. The ability of a battery to release its stored energy is a function of its demand. Higher current demands will reduce the efficiency of a battery. This paper reveals how such a mismatch occurred and its reflection on what appeared to be a battery problem.

Milled fiberglass or mica flake reinforcement can be used to control the physical properties of RIM urethanes. The addition of these reinforcements results in increased flexural modulus, decreased coefficient of linear thermal expansion, decreased elongation and decreased impact strength. Milled fiberglass is shown to orient during injection into the mold causing anisotropic behavior in the physical properties. Mica flake reinforced urethanes do not show the orientation effects found with milled fiberglass, but mica flake, causes a greater reduction in elongation and impact than does milled fiberglass. Several urethane systems are examined and the general effects of mica flake or milled fiberglass are found to be reasonably independent of the base urethane system.

General guidelines are provided in this paper that can minimize the weight of aluminum body panels. Denting, local stiffness, torsional and/or bending stiffness, strength, and vibration of body panels are considered. High strength alloys will provide the least panel weight when the governing criteria are denting, permanent set and crippling. Redesign to reduce size of unsupported outer panel areas or to increase inner panel rib size will provide the least weight when the governing criterion is stiffness.

The Reaction Injection Molding (RIM) process is being used extensively for the production of soft urethane bumper fascias and offers many advantages compared to other polymer processes. The addition of fiber reinforcement to R.I.M. urethanes has resulted in significant improvements in physical properties, making additional automotive applications possible. The development of Reinforced R.I.M. technology is currently underway at General Motors Manufacturing Development with a production scale mix-metering unit that was installed in September 1977. Reinforcement length and loading limitations, equipment wear and durability, and Reinforced R.I.M. physical properties are discussed. The advantages of Reinforced R.I.M. materials are also described along with potential automotive applications.

A high energy lead-acid battery was developed to provide, at no extra cost, a 1800 kg (4000 lb) payload electric delivery van with a driving range of 80 - 90 km (50 - 55 miles). In addition to the new high performance electrodes, an integrated approach to the total power source concept evolved new lightweight designs for battery packaging and a system engineered battery charger and an automatic topping-up facility. Despite the 40% improvement in range compared with 55 - 65 km (35 - 40 miles) for conventional traction batteries, a 4 year battery life is expected due to the reinforcing features of the tubular design adopted for the positive electrode.