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This paper describes an approach to improve the fuel economy of given cars with the aid of turbocharged SI engines of relatively small displacement, 1.6-l 4-cylinder and 2.2-l 5-cylinder configurations, to replace bigger, NA engines of the same power potential. This approach uses an engine turbocharger system which consists of a low-flow turbocharger in order to realize a given peak performance goal with good power characteristics over the entire engine-speed range. The boost pressure is controlled by a wastegate. The air/fuel mixture is prepared by a two-stage carburetor at the intake side of the TC compressor. The oxygen concentration in the exhaust gas is measured by an oxygen sensor upstream from a three-way catalyst.

A study was made to determine the effect of combinations of acoustic treatments on the interior noise levels in a 3/4 ton van. The effect of barriers, absorbers and vibration dampers in various combinations on the dBA levels are given for both idle and highway operating conditions. A noise reduction of up to 10 dBA was obtained for certain barrier and absorber combinations.

The projected high volume use of turbochargers on automobiles has presented the designer with two formidable problems - cost and mounting flexibility. The cost of an automotive turbocharger has to be less than that of a comparable unit for a diesel engine - without any sacrifice in reliability. In order to maintain the cost, the manufacturer is forced into designing one basic unit to be used in numerous applications. Therefore, the successful marketing of an automotive turbocharger will depend very heavily upon the mounting versatility designed into the basic unit. The design of the Schwitzer S6 automotive turbocharger was initiated with severe economic guidelines and mounting versatility being paramount in the design philosophy. In order to meet the design goals, a number of unique items had to be considered and incorporated into the turbocharger. The current design can be mounted from within four degrees of horizontal to within ten degrees of vertical.

Ford's new 2.3 Litre I-4 Turbocharged Engine and Powertrain was specifically developed to match the new 1979 Mustang/ Capri. This engine/vehicle combination was developed to provide the customer excellent vehicle performance, good fuel economy and driveability. Extensive vehicle and dynamometer work was done to match the turbocharger to the engine and optimize in-vehicle mid-range to high end performance. The relatively high compression ratio (9.0:1) was retained from the naturally aspirated engine to preserve low end manual transmission vehicle performance before turbocharger boost. Revisions to basic engine components and structures to insure durability will be discussed.

A detailed study of two commercial turbocharger compressor impellers with a parallel wall vaneless diffuser is reported. The study shows that present turbocharger compressor maps from different sources cannot be reliably compared as random errors can amount to ±0.05 (5 points) on efficiency (20:1 odds). Vaneless diffuser traverses reveal a flow field with backflow and separated regions. The quantitative traverse results reveal the level of uncertainty existent today in such basic deduced parameters as slip factor, backflow loss, rotor efficiency and diffuser recovery. A fully bladed and cutback bladed impeller are compared. Further work is outlined.

The interaction of turbocharger characteristics with engine design and performance parameters is presented. Turbocharger matching requires a compromise among the following variables: combustion air-fuel ratio, turbocharger characteristics, peak cylinder pressures, engine speed range capability, transient response, and overall package efficiency. The mechanisms of interactions of the above variables are reviewed to highlight the turbocharged engine designers problems. The impact of turbocharger performance limits on overall engine characteristics is reviewed with special attention focused on what limitations point out as the turbomachinery designers' job for the future.

A computer program has been developed which predicts an individual's physiological responses to various combinations of environment and exercise. The user enters information concerning the individual (height, weight, age, etc.), the environment (dry bulb temperature, air velocity, etc), the task (sit, walk, metabolic rate, etc) and the simulation (for 50 min, output every 10, etc). The program then predicts body temperatures, heart rate, sweat rate, comfort, etc and prints it out at the desired times. An important feature of the program is that variables can change during the simulation. For example, the task can change from sit to walk, the temperature from 30 C to 45 C, etc. The article gives an overview of the program and compares predictions vs data for some situations.

The impact of turbocharging on Diesel exhaust emissions has been investigated by studying, on a 4-cyl IDI Fiat engine different configurations including fuel injection optimization, exhaust gas recirculation and oxidant catalysts. The experimental results obtained during bench and chassis dynamometer tests were compared with the same tests performed on the naturally aspirated 4-cyl engine. Mathematical models were used in order to identify the regions giving the maximum contribution to regulated emissions. Particulate and organic adsorbed compounds were also measured. It appears that turbocharging can represent a reasonably good approach in order to achieve low levels of regulated emissions and particulates associated with high fuel economy.

This paper compares the calculated and measured piston transverse movement in a spark ignition engine. The induction of engine vibrations by the piston slap is studied by measuring the lateral forces at the piston skirt during the impact on the cylinder. The application of a piston movement computer program for piston development is demonstrated in the case of engine noise due to piston top land slap. The pressure differences in the main combustion chamber of an IDI-diesel engine are measured, and the effect on the piston attitude is analysed. Examples of low-noise piston design for diesel engines are presented.

As new designs of diesel engine, which emit less noise, are evolved to meet increasingly stringent noise legislation, noise from diesel fuel injection equipment could become a significant proportion of the total noise from the engine. Quieter fuel injection pumps are being produced for such engines by Lucas CAV, however their potential will not be realised unless special care is taken in the design of pump drive and mounting brackets. Impacts from the sudden take-up of backlash in the drive to the pump, and vibration of the engine surfaces to which the pump is secured, can increase pump-radiated noise considerably.

An experimental study was conducted to investigate piston-impact generated noise in diesel engines. A coherence model was used to represent the noise generating mechanisms of the engine. The model was applied to an in-line turbo-charged diesel engine. Frequency response functions were measured between the cylinder liner vibration and the engine noise, and between the combustion pressure and the engine noise. The noise coherent with piston impacts was separated from the noise coherent with combustion. Guidelines are presented showing how the results of the coherence model may be used for engine design and noise prediction.

An interactive computer program for predicting the performance of a total engine system is described. The facilities include the basic design of the valve time-area diagrams, starting from various cam profiles, wave action effects in inlet and exhaust manifolds and turbocharger matching. The program is accessed via visual display units (VDUs) and its interactive nature takes many activities from the realm of the research department into that of the design department. The results obtained from the program are validated by comparison with a well-known more sophisticated wave action program.

The design process of turbocharger impellers is recursive, involving several iterations in aerodynamics and stress analysis before finalised drawings may be produced. A comprehensive interface to both forms of analysis is discussed which relieves the designer of tedious data preparation, providing graphical interaction throughout. This interaction has been extended to the production of NC tool paths for die making and prototype manufacture and the data base created by the design procedure can be accessed for casting inspection. Finally, use is made of real time data acquisition from test cells to feed the latest empirical data into the design process.

An analytical tool for the efficient analysis of crankshaft designs has been developed. Finite element models are generated from a limited number of key dimensions which describe a family of crankshafts. These models have been verified by stress and deflection measurements on several crankshaft throws.

The use of HSLA dual phase steel is an effective method of reducing bumper weight while meeting ever increasing government performance requirements. A paper analysis, followed by a hardware evaluation, successfully substituted “dual phase” for conventional HSLA steel at a reduced thickness. Bumpers for the all-new 1979 Cadillac Eldorado were designed and released using dual phase steel with yield strengths of 70-80 ksi for the face bars. Production problems were overcome by modifications of mechanical properties and increased development experience with this steel. To achieve the full work-hardening potential of dual phase steel, bumper sections and draw dies must be designed for a uniform strain greater than three percent. Future dual phase steel for bumpers in the 80-120 ksi range is desirable, but further improvements in steel-making technology and part and die design techniques are required to achieve this goal.

Risk Analysis is a powerful technique for quantifying the risk associated with a process or product, and determining the cost/benefit tradeoffs within the system for managing risk. The application of Risk Analysis to the automotive industry is illustrated using an actual case history. The risk involved was damage to equipment and/or product due to failures within the system. The Risk Analysis identified the elements of the system which were responsible for the high frequency of damage failures the client was experiencing. Corrective action on these elements substantially reduced the occurrence of damage failures. In addition, the analysis predicted an unacceptable level of control system failures -- subsequently confirmed by operating experience. No reasonable-cost remedies were identified by the analysis. Alternate control system strategies are in the process of being evaluated.

In the past few years, there has been an increasing utilization of risk analyses of reliability and safety considerations in the design and management decision processes. Management decisions, however, are contingent on matters other than the strictly technical. A primary business objective is to gain the customers' acceptance by satisfying the criteria of product availability. This can be attained by providing highly reliable and/or easily maintainable products. These can be two different design philosophical approaches. In the design philosophy where a highly maintainable design is the best alternative, risk analysis becomes an important tool in assessing the risk of “down time” as well as the risk associated with maintenance actions. This paper will discuss the twin aspects of availability and maintainability and their impact on management decisions. A practical example is given.

Heat stress and metabolic heat retention is known to be a major contributing factor to discomfort, fatigue, reduced visual acuity, and performance decrements. Trim materials and other constituents of the seating devices have been studied to determine their effect on heat dissipation. Forty-five trim cover materials, sixteen trim pads, and five foam cushion pads were studied for impedance to body heat loss by evaporation, conduction, convection, and radiation. The range of heat flux through the various materials ranged from 6.5 BTU/FT2/HR to 35 BTU/FT2/HR. The minimum desirable heat flux value of 24 BTU/FT2/HR was established. The relationship of metabolic heat retention to physiological variations that can affect overall performance were discussed.

A PROCO Flow Simulation (PFSIM) model has been developed to calculate the angular velocity (swirl) and radial velocity (squish) as a function of crank angle for the four strokes of the motored engine cycle. In addition, the PFSIM model calculates the time dependent cylinder pressure, temperature and mass. The model accepts the following swirl-related parameters as input: dimensionless angular momentum and mass flow coefficients for a specific intake and exhaust system configuration. These parameters determine the intake-generated swirl which is computed from the angular momentum flux entering the cylinder during the induction process. An angular momentum flux swirl meter was used to obtain the required input data for three different intake port configurations, and calculations of the bulk cylinder flow were carried out with PFSIM for each intake port configuration.

This paper presents some current methods of evaluating vehicle aggressivity. Current methods under development include the use of a honeycomb front impact barrier which measures loads across the vehicle frontal area. Analytical methods are also available to model a combination of vehicles in frontal collisions and the associated occupant responses. In addition, a theoretical method is presented to measure aggressivity. The new methodology also uses a deformable barrier in frontal impact testing. This barrier, however, is modeled to represent a non-aggressive vehicle, used as a standard against which aggressivity characteristics of all cars can be measured.