Search Results

Glass-reinforced thermoplastic laminate materials which are compression molded on mechanical stamping presses have recently been added to the designer's “bag of tricks.” Guide Lamp Div., General Motors Corp., has manufactured production lamp housings with this material and process. Chevrolet Motor Div., General Motors Corp., is also manufacturing an emission control part for certain buses. Both Guide Lamp and Chevrolet have prototyped other parts using this concept. A production cycle time reduction over injection molding has been achieved. Presented here is a brief description of the process and a survey of results with these materials and molding techniques. The paper highlights the engineering studies leading to production realities at Chevrolet and Guide Lamp. Design considerations with these materials will also be given.

Fiberglass-reinforced thermoset materials offer significant advantages to the automotive body design engineer. Parts manufactured from this material possess substantially different properties than zinc or steel parts. These differences must be recognized by the part user so that necessary action may be taken to assure satisfactory part performance.

This paper discusses the use of different types of plastics in automotive moldings and relates their importance to vehicle safety. The characteristics of each type are compared and their efficiency and stability as energy-absorbing materials are discussed from the viewpoint of un-reinforced and metal-reinforced structures. Charts are provided to show the extent of plastic use in Europe, the United Kingdom, and North and South America.

An air/hydraulic brake system is offered to power disc brakes on heavy duty vehicles. The principal advantages are that the system is composed largely of service proven air brake components and the system would be compatible with existing air braked trailers.

Disc Brakes offer substantial improvements, in most cases, in performance when compared to drum brakes. Coupled with longer life, less and simplified maintenance, they should offer a most attractive brake system to truck owners and operators. Their application to the more demanding service conditions of trucks, compared to passenger cars, seems logical and necessary with greater potential gain than that which was experienced in lighter vehicles. A description of activities in developing such a brake system is given, pointing out the successes and problems encountered.

A full power hydraulic brake system has been designed for heavy-duty commercial vehicles. This system uses a hydraulic pump and one or more accumulators to generate and store energy until it is needed for braking purposes. All components have been designed specifically for vehicle braking using standard brake fluid as the energy transfer medium. Mineral oil may be used in the system if the rubber parts are replaced with parts that are compatible with the fluid.

A rapid differential near-infrared method has been developed to measure the water absorption of heavy-duty brake fluids exposed to the atmosphere during transfer and filling operations. It is based on the -OH combination band at 5180 cm-1. The method has been correlated with the SAE equilibrium reflux boiling point method and can be used in place of it to control line and finished package samples.

After inconclusive tests of steel brake rotors on a high-performance demonstration car, Armco Steel Corp. decided to take a direct approach in evaluating the application of sheet carbon steels to disc brake construction with production potential. Steel replicas of the normal cast-iron units were tested until an equivalent-performance carbon steel grade was found. Revised prototypes, with design changes, were tested with standard industry testing procedures until performance advantages were observed. Efforts are being made to determine the most efficient and economical way to produce the newly optimized steel rotor. This report is an in-progress review of the direction and first results of this project.

The friction and wear characteristics of automotive friction materials are strongly dependent on the composition and microstructure of the rotor surface. In this study we investigated the compositional and microstructural changes occurring in the surface layers of cast iron brake rotors during dynamometer tests with a typical organic friction material. Rotors were studied in the as-manufactured, lightly ground and sanded, and as-burnished conditions, as well as after 30 stops from 60 mph at a deceleration rate of 15 ft/s2. Optical and scanning electron microscopes were used to examine the surfaces. Minimum disturbance of the microstructure was found in the sanded surface, but the as-manufactured and burnished surfaces exhibited considerable disturbance. After the 30 stops the pearlite was transformed locally into martensite. Composition analysis of the burnished rotor surface showed high magnesium content.

A Rankine cycle engine is described that comprises close-coupled annular components (boiler, nozzle ring, and air condenser) corotating counter to an interior turbine wheel on a common axis. A stationary annular combustor surrounds the rotating boiler. Test runs up to 18 hp demonstrated several advantages for this kind of Rankine engine, which utilizes centrifugal force to achieve: boiler compactness, air condenser compactness (viscous drag air pumping), automatic condensate return (no separate pump), control simplicity, and few moving parts. The organic working fluid used does not support combustion and has low physiological reactivity in preliminary tests. The results appear significant for uses requiring low-polluting, quiet engines.

Several resin-bonded friction materials were used to establish the interrelationship between the resin-cure state and the functional properties. Pyrolytic gas chromatography (PGC) was used to measure the cure state of the resin and the Friction Assessment Screening Test (FAST) was used to characterize the friction and wear behavior of the materials. A phenolic resin, an oil-modified phenolic resin, and two different cashew resins were used as binders for simple resin-asbestos composites as used in brake linings. Both the PGC and functional properties of these materials showed systematic variations with changes in cure conditions of the resin. For all resins studied, a linear or bilinear relationship was found to exist between the PGC measured cure state of the resin and wear as measured by the FAST machine. A chemical kinetic model was successfully applied to relate both sample wear and a characteristic PGC peak of the resin to a unique function of cure time and temperature.

The Ford Stratified Charge Combustion Process (FCP) which utilizes direct fuel injection has been further developed for reduced exhaust emissions. With air throttling, exhaust gas recirculation, low thermal inertia exhaust manifold, and a noble metal catalyst, low gaseous emissions have been achieved at low mileage on a 1/4 ton military utility truck with acceptable fuel economy and drivability. Dynamometer and vehicle emission data and details of the fuel injection and air-fuel ratio control system are described.

This paper is a progress report on the conversion of the military L-141 gasoline engine to the Texaco Controlled-Combustion System and the evaluation of naturally aspirated and turbocharged installations in an M-151 vehicle. Relative to the standard gasoline vehicle, significant improvement in fuel economy with low exhaust emission levels were demonstrated as were the multifuel capabilities and excellent cold starting facility of the combustion concept. Possibilities for further improvement in TCCS exhaust quality through adjustment of operating parameters and add-on devices are also presented. This work was done under contract to the U.S. Army Tank-Automotive Command.

Continuing engineering educational programs provided at General Motors Institute are described. Resident and in-plant educational programs are discussed which are provided for maintenance, technician and engineering personnel. Some of the changes in emphasis occurring in electrical technology today due to developments in solid-state electronics are outlined.

A system is described which permits analysis of problems and rank ordering of action alternatives in areas of environmental concern. Complex interrelationships of various types of problems are discussed. Factors, to be considered and weighed before establishing program priorities, are pointed out. It is concluded that only through use of a logical systematic approach to environmental problems can panic programs be avoided and money and manpower be utilized most effectively.

A reliable high-temperature thermocouple for sensing turbine inlet temperature of a gas turbine engine has been developed. This sensor employs noble-metal thermoelements but retains the high signal level associated with base-metal thermocouples. A unique system of secondary junctions, contained within the device itself, allows transition to relatively inexpensive standard thermocouple materials. The development of different sampling type protective probes, including an air-cooled design, accompanied the development of the thermoelements. Some of the unsuccessful as well as the successful steps in the development are discussed, and some thoughts on future temperature sensors are given.

Advances in the development of radiation pyrometry for measuring the blade temperature in gas-turbine engines are reported. In this system, engine-mounted sensor heads collect thermal radiation from either a spot or a reasonably large area of the turbine blade. High-temperature fiber optics transmit the radiation to a remote detector housing where the photons are converted into an electrical signal by a silicon photovoltaic cell. A signal processor measures and displays on a real-time basis three temperature characteristics of the turbine blades with response better than 10 ms in most cases. Recent developments include smaller electronics, practical sensor heads, and 5000 h fiber optics. Importance of measuring the blade temperature, potential uses of the data, and actual engine tests are described.

Pavement characteristics are dominant in the prevention of wet skidding accidents. The tire modifies the pavement properties together with the climatic conditions. Laboratory methods and site investigations have led to an understanding of the relative importance of pavement macro- and microtexture and to the isolation of the factors influencing wet road-hold of vehicles. Improvements in pavement characteristics are urgently required if wet skidding accidents are to be reduced; these changes will also influence future tire design.

This paper outlines the design features of the 4-cyl, overhead camshaft 1.6-liter Dodge Colt engine together with four other single and double overhead camshaft engines in the same family. These engines have been developed for high performance with a compact size and reduced weight. The Dodge Colt engine, in particular, has been designed to be in compliance with stringent 1972 United States emissions standards. Emission controls achieved with this engine, such as improved combustion chamber design of small surface/volume ratio and various control systems, are described in some detail.

An analytical method is described for estimating and graphically comparing the amounts of mass emissions from automobiles, buses, commuter trains, and rail transit given the emission characteristics of each type of vehicle. Emissions considered included carbon monoxide (CO), hydrocarbons (HC), nitrogen dioxide (NO2), and sulfur dioxide (SO2). These mass emissions are expressed in “grams per person mile” as well as “grams per vehicle mile” in order to consider their quantity based on the movement of people as well as on the movement of vehicles. The relative effects of these pollutants are also presented. Information from this method can be used to estimate the quantity of emissions produced in a specified area given the travel characteristics of that area. Changes in the amount of emissions resulting from persons who change their mode of travel can also be estimated. An example is used to demonstrate the method and application.