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During the automotive brake system design and development process, a large number of performance characteristics must be comprehended, assessed, and balanced against each other and, at times, competing performance objectives for the vehicle under development. One area in brake development that is critical to customer acceptance due to its impact on a vehicle's perceived quality is brake pedal feel. While a number of papers have focused on the specification, quantification and modeling of brake pedal feel and the various subsystem characteristics that affect it, few papers have focused specifically on brake corner hoses and their effect on pedal feel, in particular, during race-track conditions. Specifically, the effects of brake hose fluid consumption pedal travel and brake system response is not well comprehended during the brake development process.

Variable valve actuation has become a very popular feature in today's engines. With many of these systems being hydraulically actuated, the engine lubrication system requires enhancement to support their function. To expand the system's operational range with respect to speed and temperature, a traditional solution has been to increase oil pressure by increasing pump displacement. To better optimize the system, a variable displacement vane pump has been adapted to the engine lube oil system. Based on existing transmission pump technology, a pivoting cam ring design is employed that is able to vary the pump's displacement as a function of pump regulating oil pressure which in-turn provides a net reduction in its drive torque. While others have addressed this issue using complex and expensive pressure regulating systems, this passive solution requires no valves or additional hardware.

Homogenous Charge Compression Ignition (HCCI) combustion offers significant efficiency improvements compared to conventional gasoline engines. However, due to the nature of HCCI combustion, traditional HCCI engines show some degree of sensitivity to in-cylinder thermal conditions; thus higher cylinder-to-cylinder variation was observed especially at low load and high load operating conditions due to different injector characteristics, different amount of reforming as well as non-uniform EGR distribution. To address these issues, a cylinder balancing control strategy was developed for a multi-cylinder engine. In particular, the cylinder balancing control strategy balances CA50 and AF ratio at high load and low load conditions, respectively. Combustion noise was significantly reduced at high load while combustion stability was improved at low load with the cylinder balancing control.

Aqua-ammonia absorption refrigeration cycle and R-134a Vapor jet-ejector refrigeration cycle for automotive air-conditioning were studied and analyzed. Thermally activated refrigeration cycles would utilize combustion engine exhaust gas or engine coolant to supply heat to the generator. For the absorption system, the thermodynamic cycle was analyzed and pressures, temperatures, concentrations, enthalpies, and mass flow rates at every point were computed based on input parameters simulate practical operating conditions of vehicles. Then, heat addition to the generator, heat removal rates from absorber, condenser, and rectifying unit, and total rejection heat transfer area were all calculated. For the jet-ejector system, the optimum ejector vapor mass ratio based on similar input parameters was found by solving diffuser's conservation equations of continuity, momentum, energy, and flow through primary ejector nozzle simultaneously.

A spectroscopic diagnostic system was designed to study the effects of different engine parameters on the chemiluminescence characteristic of HCCI combustion. The engine parameters studied in this work were intake temperature, fuel delivery method, fueling rate (load), air-fuel ratio, and the effect of partial fuel reforming due to intake charge preheating. At each data point, a set of time-resolved spectra were obtained along with the cylinder pressure and exhaust emissions data. It was determined that different engine parameters affect the ignition timing of HCCI combustion without altering the reaction pathways of the fuel after the combustion has started. The chemiluminescence spectra of HCCI combustion appear as several distinct peaks corresponding to emission from CHO, HCHO, CH, and OH superimposed on top of a CO-O continuum. A strong correlation was found between the chemiluminescence light intensity and the rate of heat release.

Extending engine-oil-change intervals is of interest from the standpoint of reducing used oil disposal and reducing time and expense of maintenance. However, the oil must be changed before serious oil degradation and engine damage occur. Three variables which influence oil degradation were chosen for investigation: base oil composition (synthetic oil versus mineral oil), trip length (short trips versus long trips), and driving schedule (degrading an oil during a given type of service, then changing to another type of service without an intervening oil change). Analysis of oil samples taken throughout the testing program indicated that type of service (freeway compared to short trip) influenced oil degradation to a greater extent than oil type. That is, API SG-quality synthetic oil in short-trip service degraded faster than borderline SG-quality mineral oil in long-trip service.

A computer code for predicting cooling air flow through the radiator and the condenser has been developed. The Reynolds-averaged Navier-Stokes equations, together with the porous flow model for the radiator and the condenser, were solved to simulate front end air flow and the engine compartment flow simultaneously. These transport equations were discretized based on a finite-volume method in a transformed domain. The computational results for a simplified engine compartment showed overall flow information, such as the cooling air flow through the radiator and the condenser, the effects of an air dam, and the effects of fresh air vents near the top of the radiator and the condenser. Comparison of the available experimental data with the analysis showed excellent prediction of the cooling air flow through the radiator and the condenser.

Component operating temperatures affect both the reliability and performance of automotive alternators. It is desirable to keep the rectifier bridge and regulator temperatures below 175 C because of the semiconductors contained in this area. At temperatures greater than this, expected lifespans have been observed to decay exponentially [1]. The air flow field surrounding an alternator and component temperature fields were investigated with Computational Fluid Dynamics (CFD) simulations. The objectives of the simulations were to examine the velocity field for the flow passage and the temperature fields for the components. Design proposals have been made to improve the air flow and to reduce the operating temperature. An initial investigation was performed by setting an alternator in a test configuration and applying the appropriate heat generation for each component. The high temperatures in the alternator components occurred in the stator and the rectifier.

A global thermal model of a vehicle powertrain is used to quantify how different engine design and powertrain calibration strategies influence the performance of a vehicle heating system. Each strategy is evaluated on its ability to improve the warm-up and heat rejection characteristics of a small-displacement, spark-ignition engine while minimizing any adverse effect on fuel consumption or emissions. An energy audit analysis shows that the two strategies having the greatest impact on heating system performance are advancing the spark and forcing the transmission to operate in a lower gear. Changes in head mass, exhaust port diameter, and coolant flow rate influence the coolant warm-up rate but have relatively little effect on steady state heat transfer at the heater core.

USING a high-speed motion picture camera, flame photographs were taken of the combustion process associated with the starting of hot gasoline engines. Compression ignition at isolated points followed by normal combustion caused peak cylinder pressures to occur prior to top dead-center under some low-speed engine conditions. In addition, an abnormal combustion phenomenon was observed in the last part of the charge to burn. The reaction rate was appreciably faster than normal for the engine speed and much slower than is usually observed in knocking combustion at normal engine speeds.

THE automotive and petroleum industries have been concerned for many years with the mutual problem of improving the thermal efficiency of gasoline engines. Great progress in refining technology, as well as advances in engine design in recent years, have made it desirable to take a new look at high-compression engines. This paper describes an investigation of the effect of compression ratio on engine efficiency over a range of compression ratios from 9/1 to 25/1. The results show that the thermal efficiency of the multicylinder engines used in this study peaked at a compression ratio of 17/1. The decrease in thermal efficiency at higher compression ratios is due primarily to delay in the completion of the combustion process. This paper received the 1958 Horning Memorial Award.

The development of a plasma jet ignition system is described on a 4-cyl, 140 in3 engine. Performance was evaluated on the basis of combustion flame photographs in a single-cylinder engine at 20/1 A/F dynamometer tests on a modified 4-cyl engine, and cold start emissions, fuel economy, and drivability in a vehicle at 19/1 air fuel ratio. In addition to adjustable engine variables such as air-fuel ratio and spark advance, system electrical and mechanical parameters were varied to improve combustion of lean mixtures. As examples, the air-fuel ratio range was 16-22/1, secondary ignition current was varied from 40 to 6000 mA, and plasma jet cavity and electrode geometry were optimized. It is shown that the plasma jet produces on ignition source which penetrates the mixture ahead of the initial flame front and reduces oxides of nitrogen emission, in comparison to a conventional production combustion chamber.

The level of filtration in an engine can have a significant impact on wear rates due to abrasive particles. Tests were conducted to establish a relationship between the level of filtration and abrasive engine wear. Although the tests were run in a laboratory environment, wear was reduced by as much as 70% by going from a 40 micron filter to a 15 micron filter. Testing was performed on a heavy duty diesel engine and later with an automotive gasoline engine. The results from both engines were consistent and showed that the relationship developed can be applied to nearly any internal combustion recipricating engine.