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Intake and exhaust valve control has been combined with engine calibration control by an on-board computer to achieve a Variable Displacement Engine with improved BSFC during part throttle operation. The advent of the on-board computer, with its ability to provide integrated algorithms for the fast accurate flexible control of the entire powertrain, has allowed practical application of the valve disabler mechanism. The engine calibration basis and the displacement selection criteria are discussed, as are the fuel economy, emissions and behavior of a research vehicle on selected drive cycles ( Metro, Highway and Steady State ). Additionally, the impact upon vehicle driveability and other related subsystems ( e.g., transmission ) is addressed.

A mechanism has been developed which deactivates selected valves on a spark ignition engine. Greater fuel economy results from reduced throttling losses when using fewer cylinders under light load conditions. Several approaches were considered, with the releasable fulcrum proving to be the most effective concept. Subsequent engineering efforts refined the design to develop a simple bolt-on device which would meet specific performance requirements.

A comprehensive long-term test on bare, anodized, plated, and organic-coated aluminum bumper stock is underway at atmospheric test sites at Pompano Beach, Florida; Phoenix, Arizona; Richmond, Virginia; and Chicago, Illinois. Aluminum alloys exposed originally in 1975 included 7016, 7046, X7029, and two experimental compositions. New exposures in 1977 included alloys 7129, 7021, 6009 and 6010. Specimens are scheduled for removal after 1-, 2-, and 4-years - 2-year panels were retrieved and evaluated in 1977 from Florida and Phoenix. One-year results from Richmond and Chicago will be reported here. Fullsize aluminum bumpers (with and without rub strips) having organic coatings, anodized coatings, and chrome-plated finishes were exposed also, along with chrome-plated steel.

The authors developed a method to measure the air-fuel ratio at local points within the combustion chamber. The primary point is to obtain the pre-combustion air-fuel ratio of the mixture from the HC (vaporized fuel) and O2 concentrations. This procedure which consists of three parts, gas sampling, gas transport and gas analysis, renders it possible to perform direct quantitative HC analysis of samples. This method is carried out by either of two techniques: multi-cycle sampling (MCS) and single cycle sampling (SCS), and the average air-fuel ratio of many engine-cycles and the single engine-cycle were obtained respectively.

Bumper facebars formed from high strength aluminum sheet provide the design engineer with a cost effective way to achieve styling flexibility with substantial weight savings. Several prototype programs have defined candidate alloys, manufacturing sequences, and important part and tooling design guidelines for forming bumpers from aluminum sheet. The results of these programs are summarized. Four case histories are discussed.

Three-way catalysts provide a means of catalytically achieving lower NOx emission levels while maintaining good control of HC and CO emissions. However, very accurate control of air-fuel ratio is necessary. The precise air-fuel ratio control required is accomplished by employing a closed loop fuel metering system in conjunction with an exhaust gas sensor and an electronic control unit. To gain production experience with this type of system, General Motors is introducing it on two 1978 engine families sold in California. One is a 2.5 litre L-4 engine and the other is a 3.8 litre V-6 engine. Closed loop controlled carburetors are used on both systems. This paper discusses these 1978 systems. The components used on both systems are described and emission and fuel economy results are reviewed.

The objective of this paper is to describe the Ford Motor Company (Ford) approach of meeting exhaust emission regulations with a three-way catalyst and feedback control system. A pilot program was initiated to gain production experience with three-way catalyst systems in anticipation of expanded usage to meet future emission standards. The Ford system consists of a three-way catalyst with feedback control monitoring the exhaust oxygen concentration and controlling the fuel flow to produce a stoichiometric exhaust mixture. Mixture control is critical since catalyst NOx conversion efficiency is diminished when the exhaust mixture deviates from stoichiometry. Briefly, the control loop consists of zirconium dioxide exhaust sensor to indicate oxygen concentration, an electronic control unit, a vacuum regulator to proportion a vacuum signal to the carburetor, and a feedback controlled carburetor with vacuum modulated main fuel system.

This paper reports an effort to integrate into an engine/catalyst system the best available technologies in electronic engine controls, fuel systems, and catalysts for the purpose of developing a 4000 to 4500 lb vehicle that combines good fuel economy with the ability to meet the 0.41/3.4/0.40 gm/mi emission objectives for HC/CO/NOx. The system has been installed in a 1977 Ford Granada and tested under CVS-CH conditions with two different combinations of catalysts. The results of these experiments, along with analyses of the performance of major electronic and catalytic subsystems, are presented and discussed.

Measurements have been made of the emissions from a prototype three-way catalyst automobile, during normal and simulated malfunction driving conditions. Four ceramic-supported catalyst compositions were investigated, ranging from Rh through two mixtures of Rh-Pt to Pt. Driving conditions included cyclic and cruise modes. Under normal operating conditions no HCN was detected. Under rich malfunction conditions, HCN was generally observed, even in the absence of a catalyst. In some cases, catalysts appeared to remove HCN from the exhaust gas; in others they increased its level. The highest emission rate for HCN was observed for the Rh catalyst, about 40 mg/km at 64 kph cruise.

The selectivities of iridium (Ir), platinum (Pt) and rhodium (Rh) catalysts for reducing NO in the presence of excess O2 in two synthetic fuel-lean exhaust gases have been determined, before and after a severe heat treatment. When tested at 500°C, the order of selectivity was Ir>>Rh>Pt for fresh catalysts, and Pt>Rh for treated catalysts. When tested at 400°C, the treated Pt and Rh catalysts were identical in selectivity to the fresh Ir catalyst. A catalyst called Leanox* was developed which showed higher NO selectivity than the fresh Ir catalyst. The advantages of incorporating this catalyst upstream of a conventional three-component-control catalyst to improve NO conversion on the fuel-lean side of stoichiometry were demonstrated in laboratory tests.

An electronically controlled closed-loop carburetor system has been developed. This system's air-fuel ratio control is characterized by the air bleeds being controlled by turning the solenoid valves on and off at a constant frequency. The frequency above 30 Hz was desirable for practical performances. Some improvements and developments were made to the carburetor, the solenoid valve and the control unit. In application of this system to a three-way catalytic system with O2 sensor, the emissions met the 1978 Japanese standards.

Under oxygen-deficient (rich) conditions, a potential route to maintaining control of carbon monoxide (CO) and hydrocarbon (HC) emissions in a three-way system is through reactions of these pollutants with water vapor (H2O). The importance of such reactions over supported rhodium was investigated in the laboratory. The water-gas shift (CO + H2O) was insignificant. Steam reforming (HC + H2O) took place, but gave CO as a product. Thus, if CO conversion governs the rich-side effectiveness of a three-way catalyst, steam reforming which converts HC to CO is unlikely, in itself, to improve three-way performance.

Three basic tire constructions (diagonal, bias belted, and radial) were evaluated via a designed experiment to determine the effect of tire construction on wet traction. Significantly, no one type of construction displayed an inherent advantage for straight ahead wet traction. In addition, investigation within the radial construction framework revealed that stabilizer ply material and angle have little influence on straight ahead wet traction. Tire construction was found to have a significant effect on wet cornering potential.

An on-stream gas chromatographic technique was developed to analyze grab samples of diluted and undiluted vehicle exhaust for the reduced sulfur compounds which cause rotten-egg odors. This method was used to conduct a brief survey of two cars with modified carburetors, four customer cars with odor problems, and five experimental three-way catalyst cars. The cars were tested on a chassis dynamometer using a driving cycle developed for this study. Hydrogen sulfide and carbonyl sulfide were frequently measured. Ethyl mercaptan and fuel sulfur components were occasionally detected. The sulfides were emitted most often when the catalyst was hot, the space velocity was low and the carburetion was rich. The maximum H2S or COS concentration measured in undiluted exhaust was <10 ppm. Therefore, these emissions pose no known health problem, but can be an odor problem.

A water depth measuring system has been developed to allow routine and efficient determination of water depths on road surfaces used for tire traction testing. The system consists of a multi-probe transducer unit (which attaches to the front bumper of most standard automobiles) and an in-car electronics package with direct digital and analog readout capabilities. Water depth measurements are taken at one foot (305 mm) intervals at vehicle speeds from two to five miles per hour (3.2 to 8.0 km/hr). Either individual or accumulated average water depths can be digitally displayed to the driver/operator.

This report deals with the tests made on the hydroplaning phenomenon of car, truck and bus tires using the interior of a dynamic tire testing machine. For car tires, the relationship between braking force and slip ratio and between cornering force and slip angle as affected by hydroplaning were investigated. Studies were also made of the influence of the difference between radial-ply and cross-ply tires, inner pressure, load, thickness of the water film, etc.. Next, a study was conducted concerning the effect of hydroplaning on the cornering properties of truck and bus tires.

The Mobile Tire Traction Dynamometer measures the braking and cornering traction of passenger car tires on outdoor pavements at highway speeds. Its hydrostatic wheel speed control system, wheel loading and positioning system, pavement wetting system, transducers and instrumentation are described in detail. The data processing methods for its several test modes are explained. Results of experiments (1) to determine the effect of the rate of change of slip on the peak braking coefficient, (2) to identify filters suitable for peak braking coefficient measurement, (3) to determine the effect of the rate of change of slip angle on the lateral force coefficient, and (4) to explore various pavement friction testing methods are included as examples of the use of this testing device.

New Federal safety legislation requires school bus body manufacturers to increase the strength of all joints between sheet steel body panels and between panels and support beams. This paper describes two new epoxy structural adhesives, and a new assembly process called “rivet bonding”, which is now used for about 98% of all school buses produced for sale in the U.S. Advantages include noise reduction plus substantial savings in labor and other costs when compared to the riveting or other mechanical fastening methods which would be required to provide equivalent joint strengths.

EEC Braking Directives mandate several system functions that require special equipment, in order to gain Type Approval. Industry, generally, exerts pressure to ensure that legislation is not design restrictive and, since the major manufacturers of air brake equipment are based in Britain and Germany, where the brake systems prior to 1971 were quite different, there are some interesting contrasts in the valves and system principles employed to meet the same requirements. Interpretation of the Directives and establishment of uniform test methods have given rise to several problems and this continues to be a field in which much work is required. Consequently, a period of stability is sought before further changes are introduced.

The rationale for the increasing use of automotive adhesives is discussed as are the basic principles of adhesive and process selection. The paper concludes with a brief summary of why adhesives are used in thirteen different automotive applications.