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Brake caliper and corner behavior in the off-brake condition can lead, at times, to brake system performance issues such as residual drag (and related issues such as pulsation, judder, and loss of fuel economy), and caliper pryback during aggressive driving maneuvers. The dynamics in the brake corner can be strikingly complex, with numerous friction interfaces, rubber component and grease dynamics, deflections of multiple components, and significant dependence on usage conditions. Displacements of moving parts are usually small, and the residual forces in the caliper interfaces involved are also small in comparison with other forces acting on the same components, making direct observation very difficult. The present work attempts to illuminate off-brake behavior in two different conditions - residual drag and pryback - through the use of low-range pressure distribution sensors placed in between the caliper (pistons and fingers) and the brake pad pressure plates.

Allison Gas Turbine Division of General Motors is performing the first phase of a multiphase development project aimed at demonstrating an electric vehicle based on a proton exchange membrane (PEM) fuel cell. This work is sponsored by the Office of Transportation Technologies of the U.S. Department of Energy (DoE) through the DoE's Chicago Field Office (Contract No. DE-AC02-90CH10435). This work complements major efforts under way to produce electric vehicles for reducing pollution in key urban areas. Battery powered vehicles will initially satisfy niche markets where limited range vehicles can meet commuter needs. The PEM fuel cell/battery hybrid using methanol as fuel potentially offers an extremely attractive option to increasing the range, payload, and/or performance of battery powered vehicles.

THE design and development of the new valve-in-head V-8 Chrysler engine of 7.5 compression ratio are described here. Among the features discussed by the authors are: the hemispherical combustion chamber, V-8 cylinder arrangement, double-breaker distributor, “thermal flywheel” on automatic choke, and exhaust-heated and water-jacketed throttle bodies. The hemispherical combustion chamber was adopted after it had displayed excellent volumetric and indicated thermal efficiencies, and an ability to maintain these high efficiencies in service. The high volumetric efficiency, for example, is considered to be due to such design features as valves not crowded together, nor surrounded closely by the combustion-chamber walls. They are thereby fully effective in the flow of the fuel-air mixture and the exhaust gases. The authors also present performance data for this engine, which, at full throttle, develops 180 hp at 4000 rpm and 312 ft-lb of torque at 2000 rpm.

In 1999, the Society of Automotive Engineers established the Fuel Cell Standards Committee (FCSC). The Committee is organized in subcommittees that address issues such as Interface, Hydrogen (H2) Quality, Safety, Performance, Emissions and Fuel Consumption, Recycling and Terminology. Since its inception the SAE/FCSC has published several recommended practices, which have drawn the attention of national and international organizations. These include SAE J2578 (Fuel Cell Vehicle Safety), SAE J2600 (Compressed H2 Surface Vehicle Refueling Devices), and SAE J2594 (Recyclability of Fuel Cell Systems). The need for having one common grade of hydrogen for all US commercial hydrogen-refueling stations for FCVs was the reason to establish the H2 Quality Task Force (HQTF) in late 2003. At the present time there is no representative US-national or international standard addressing the quality of hydrogen fuel that is acceptable for fuel cell vehicles.

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.

The basic theory and the techniques upon which the Air Conditioning Analytical Simulation Package (A/CASP) computer program system was developed is outlined. Methods for simulating car air conditioning components, systems, and cool-down performance by computerized mathematical models are presented. Solution techniques for the models of the evaporator, condenser, compressor, and vehicle are outlined. The correlation of test data and analytical predictions is demonstrated.

We propose a composite thermal model of the vehicle passenger compartment that can be used to predict and analyze thermal comfort of the occupants of a vehicle. Physical model is developed using heat flow in and out of the passenger compartment space, comprised of glasses, roof, seats, dashboard, etc. Use of a model under a wide variety of test conditions have shown high sensitivity of compartment air temperature to changes in the outside air temperature, solar heat load, temperature and mass flow of duct outlet air from the climate control system of a vehicle. Use of this model has subsequently reduced empiricism and extensive experimental tests for design and tuning of the automatic climate control system. Simulation of the model allowed several changes to the designs well before the prototype hardware is available.

A system for controlling gasoline evaporation losses from 1970 model Chrysler Corp. cars and light trucks was developed, certified for sale in California, and put into production. Evaporation losses from both the carburetor and the fuel tank are conducted to the engine crankcase for storage while the engine is shut down. The vapors are removed from the crankcase and utilized in the combustion process during subsequent vehicle operation. Particularly interesting in this unique, no-moving parts system, are the reliability and durability, and the vapor-liquid separator “standpipe.”

A new 3.5 liter, 60 degrees V6 engine has been designed specifically for Chrysler's 1993 MY line of mid-size sedans - Dodge Intrepid, Eagle Vision, Chrysler Concorde and New Yorker. This new engine features many new components for enchanced performance. The cylinder head has a single overhead cam, four valve-per - cylinder design. The intake system is a cross-flow design equipped with dual throttle bodies, and the manifold also incorporates a vacuum operated tuning valve that increases the mid-range torque of the engine. A windage tray is used on every engine to reduce drag on the rotating components within the crankcase. Dual knock sensors (one per cylinder bank) are used to take advantage of the aggressive spark advance and high compression ratio. The engine also utilizes a plastic, helical, water pump impeller that contributes to low parasitic power losses. The engine incorporates many components and features to ensure durability.

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.

TURBOGLIDE is the deluxe automatic transmission of the General Motors Chevrolet. One of its most important features is that its performance ratio is available at any throttle position, enabling control of torque ratio and engine output by the throttle pedal. The system includes a five-element torque converter, pump, three turbines, and the dual stator. The entire installed unit weighs 148 lb, a result of the general arrangement and the use of aluminum in the case and bell housing. The authors discuss the basic operating principle of the transmission, the arrangement, performance, torque distribution, control system, and valve body.

This paper describes the recent efforts on developing an automotive climate control system throughout integrating an electrically-controlled variable capacity scroll compressor with a fuzzy logic control-based refrigerant flow management. Applying electrically-controlled variable capacity compressor technology to climate control systems has a significant impact on improving vehicle fuel economy, achieving higher passenger comfort level, and extending air and refrigerant temperature controllability as well. In this regard, it is very important for automotive climate control engineers to layout a system-level temperature control strategy so that the operation of variable capacity compressor can be optimized through integrating the component control schemes into the system-level temperature control. Electronically controlled expansion devices have become widely available in automotive air conditioning (A/C) systems for the future vehicle applications(1, 2, 3 and 4).

Gasoline direct injection technology is receiving increased attention among automotive engineers due to its high potential to reach future emission and fuel economy goals. This paper reports some of the design and development techniques in use at Chrysler as applied to four-stroke Direct Injection Spark Ignition (DISI) engines. The spray characteristics of Chrysler's single-fluid high-pressure injector are reported. Tools used in the design process are identified. Observations of the in-cylinder fuel/air mixing process using laser diagnostic techniques and Computational Fluid Dynamics (CFD) are described. Finally, combustion and emissions characteristics using Design of Experiment (DoE) tests are presented.

A better understanding of turbulent kinetic energy is important for improvement of fuel-air mixing, which can lead to lower emissions and reduced fuel consumption. An in-cylinder flow study was conducted using 1548 Laser Doppler Velocimetry (LDV) measurements inside one cylinder of a 3.5L four-valve engine. The measurement method, which simultaneously collects three-dimensional velocity data through a quartz cylinder, allowed a volumetric evaluation of turbulent kinetic energy (TKE) inside an automotive engine. The results were animated on a UNIX workstation, using a 3D wireframe model. The data visualization software allowed the computation of TKE isosurfaces, and identified regions of higher turbulence within the cylinder. The mean velocity fields created complex flow patterns with symmetries about the center plane between the two intake valves. High levels of TKE were found in regions of high shear flow, attributed to the collisions of intake flows.

The use of regrind acrylonitrile-butadiene-styrene (ABS) for automotive parts and components results in two types of financial savings. The first is the shared monetary savings between General Motors and the molder for the difference in the virgin resin price versus price of the ABS regrind. The second is a societal energy savings seen in the life cycle of virgin ABS versus reground ABS. An added benefit is the preservation of natural resources used to produce virgin ABS.

The Cadillac Electronic Climate Control heating and air conditioning system provides automatic control of the passenger compartment temperature. It utilizes a microcomputer to control the operation of electrical, mechanical and vacuum components that regulate the amount and temperature of air delivered into the car to maintain the “customer set” comfort level. The first step in the evolution of this new system was to define the performance requirements. With this established, the system was then designed, tested and developed in the laboratory and on the road until this desired performance was achieved.

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.

THIS description of the hydraulic control used with the hydra-matic transmission reveals how the control operates to change ratios under power without direction from the driver. The control's pattern of automatic shifting for ordinary, high-range driving has been selected as the best compromise between top performance and low ratio of engine noise to wind noise. The control's low range shifts gears according to performance dictates alone, furnishing greater power for extreme conditions at low speeds and enabling the driver to use his engine as a brake on steep descents. Heart of the control system is a double hydraulic governor, sensitive both to car speed and throttle opening. THIS paper, as well as the two that follow, one by Messrs. Nutt and Smirl and the other by Mr. Kimberly, make up a symposium on automatic transmission components presented at the 1947 SAE Summer Meeting.

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.