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A systematic study on particulate mass emission from a high-speed direct-injection diesel engine was conducted using a mini-dilution sampling method. Effects of fuel-air equivalence ratio, engine speed, injection timing, and swirl intensity are presented and discussed with special regard to soluble organic fraction (SOF) and hydrocarbons. Results show that these concentrations are greatly affected by ignition delay or by temperature level in the engine cylinder. As the sources of SOF and hydrocarbons, local and bulk quenching of the charge, interaction of the fuel spray with the combustion chamber walls, and slow thermal decomposition of fuel are considered and discussed. Among them, the significance of the fuel decomposition is pointed out, by separate experiments on a simulated engine by using an in-cylinder gas-sampling technique.

An 8.5 inch bore two stroke engine has been modified into a photographic test rig in which pictures of the complete combustion chamber could be taken vertically upwards through a perspex crowned piston, using a high speed camera. Tests were carried out using several nozzles of the same total hole area. Two fuelling rates and three different air supply pressures were used. At each test condition thirteen cycles of fired data were recorded on 16 mm high speed colour film. At the same time synchronised transient cylinder pressure and fuel injection data were recorded using an on-line data acquisition system. Correlation of jet development from photographs with heat release deduced from the cylinder pressure diagrams using a standard single zone technique show differences due to changes in the hole configuration and in air supply pressure, with approximately constant fuel injection rates.

The compression ratio of a direct-injection Diesel engine was decreased by steps. The total hydrocarbon emissions and various component stresses were measured. HC emissions rise hyperbolically when compression ratio decreases. The curve can be shifted towards lower CR values by increasing load, charge air pressure or charge air temperature. The measured ignition delays are in every respect in significant agreement with the HC emissions, leading to the hypothesis that excessive quantities of the injected fuel are deposited on the wall when the compression ratio decreases. If the calculated paths of the whole jet up to the beginning of combustion are put in relation to the HC emissions there result critical ranges for the jet tips beyond which the emissions increase drastically. By that the conditions for reducing the influence of compression ratio can be considered for granted.

It is now well-known that not only dimensions but also manufacturing tolerances and layouts of oil holes and grooves affect engine bearing performance. The present paper will show that some new features of machining and operating conditions can also influence bearing operation. Scratches caused by debris in the oil and the size of the counterbore on cross-drilled main journals can have highly detrimental effects. Results will also show how out-of-roundness and ellipticity affect bearing operation. This information can be vital for designing better engine bearings.

Reducing direct friction losses between the surfaces of sliding engine parts has - in many cases - only little influence on the effective fuel consumption, especially in engines with a high load-factor. Therefore, the higher expenditures in development and production result in a poor cost/benefit-relation. But in quite a lot of cases friction losses can be reduced by shifting the speed-and load-range of the engine. Together with optimizing oil flow and viscosity behaviour advantages on behalf of the motor cycle-process as well as of engine behaviour and engine life are reached, thus reducing fuel consumption even further together with better engine performance. Some examples are given and discussed in detail.

In this study, the effects of engine speed, air-fuel ratio, combustion timing, intake-air temperature, and coolant and oil temperature on exhaust gaseous emissions (nitric oxide, carbon monoxide and hydrocarbons) and particulate emissions (particulates, volatiles and smoke) were investigated in a single-cylinder, divided-chamber diesel engine. In addition, the trade-off behavior of the pollutants was investigated. To aid in the interpretation of the experimental findings, a single-chamber, single-zone heat release model utilizing experimental main-chamber pressure-time data was employed. The large increase in nitric oxide emission index caused either by increasing the air-fuel ratio or by advancing the combustion timing is attributed to the proportionally larger amounts of fuel that burn at near TDC conditions.

New valve hardfacing materials have been developed for use in either gasoline or diesel engines. The objective of reducing and/or eliminating cobalt as a necessary alloy addition has been achieved. Improvements in the method of application to the valve have increased productivity, and de-creased quality costs.

Measurements of cylinder and inter-ring pressures and top ring axial movement were made on a 4-stroke V8 diesel engine running at full power, in order to understand differences in observed oil consumption and blowby for 5 different ring and piston combinations. In each case the parameters were also calculated using a newly developed computer program which combines the effects of ring lift and twist, inter-ring gas pressures, ring profile and tension and liner finish on ring hydrodynamics and gas flow. Encouraging correlation was shown between measured and predicted results.

Accelerated wear of chromium plated piston rings by an unidentified wear mechanism has been occasionally observed in small bore, high speed diesel engines in the field. This chromium plate wear phenomenon has been successfully reproduced in laboratory engine tests using chemically pitted cylinder liners with rough surface finishes. This paper reviews the laboratory test program which was developed a) to understand and identify the wear mechanism and b) to maintain ring wear life through piston ring modifications.

Measurement of piston frictional forces during engine operation is valuable for improved fuel economy engine design. The measurement, however, is not easy work because the frictional forces are small compared with the gas and inertia forces. Several years ago, at the Musashi Institute of Technology, frictional forces were measured with a movable bore with pressure balancing. Recently, the pressure balancing devices have been improved and adapted for small engines. The piston frictional forces in a small diesel engine and a gasoline engine have been measured with the new device. The characteristics of the friction forces and the comparison between engine sizes, gasoline and diesel engines have been clarified and the effect of multi-grade oil and friction modifiers have been tested.

Apart from its many other functions, the piston ring also has the task of dissipating heat from the piston to the cylinder wall. This heat flow alters the contact pressure of the piston ring against the cylinder and can result in a lack of effective sealing with extremely high pressure at the ring ends. The work presented in this paper enables the effect of the heat flow on the ring shape as a function of piston ring material and dimensions to be calculated from the temperature difference between piston and cylinder wall and to integrate these findings into the manufacturing process, i.e., noncircular shaping. This makes it possible for the first time to produce piston rings that do not have the disadvantages in engine application of the uncontrolled thermal deformation -scuffing marks and leakage at the ring ends.

This paper describes a unique and uncomplicated method of stratified-charging a two-stroke cycle engine which assists in reducing the short-circuited loss of fuel during scavenging. Performance characteristics as presented were acquired from tests conducted on a 400 cm3 naturally aspirated, single cylinder, spark ignition two-stroke engine with carburettor control of gasoline fuel, the design and construction of the engine also being done at The Queen's University of Belfast. Using a tuned exhaust pipe, the engine produces a peak power of 16 kW at 5000 rev/min and has a minimum brake specific fuel consumption of 0.275 kg/kWh. Moreover, for the tests presented at full and quarter throttle openings, virtually all of the brake specific fuel consumption values are below 0.36 kg/kWh. Most of the performance characteristics shown at various engine speeds are as a function of air/fuel ratio. This paper is a continuation of that presented as SAE 830093.

Several highly technical skills are required to design and develop a self-propelled vehicle. One such skill is to design or select the appropriate size drive train. The more accurately this can be accomplished, the more significant will be the savings in development cost. Various references are available on the theoretical approach; however, a significant unknown is the relationship to practical applications. Zahnradfabrik Friedrichshafen AG has over many years of experience developed a computer program that can reliably assess the service life of power train designs. The reliability of this approach has been proven by both vehicle manufacturers and end users.

A dual fueled diesel engine system with diesel fuel and reformed methanol has been investigated. Methanol can be reformed to reformed methanol (hydrogen 67% + carbon monoxide 33%) over suitable catalyst. The reformed methanol contains 20% more energy than methanol. Fundamental data of an electric heated reformer, performance of the dual fueled diesel engine to which hydrogen and carbon monoxide fed from gas bombs as a preliminary experiment, and then performance of the diesel engine with an onboard reformer were tested. In consequence, the feed of the reformed methanol improves the diesel engine performance.

A cycle simulation has been developed and used to investigate the combustion process and performance trends of coal particle fueled, direct-injected diesel engines. Particle reaction rates were calculated as a function of crank angle and depended on instantaneous conditions of both the cylinder gas and particles. Assumptions were made that cylinder gas was uniformly mixed and the particles were solid spheres of pure carbon. The results of the study suggest that the particles will not self-ignite in the cylinder, but will burn successfully with use of a pilot ignition. Thermal efficiency was found to be sensitive to the selected initial particle size and the engine operating speed.

Mitsubishi has developed the new, compact, water-cooled vertical type 2-cylinder diesel engine model K2AS and brought it to market in spring of '82. The K2AS is a small-sized engine of 451 cc total displacement and 10HP/3600 rpm maximum output. Its weight of 58 kg is light enough to use this diesel engine for various machines which have formerly been driven by gasoline engines. The well matched combustion chamber and injection system realize low fuel consumption, low noise and easy engine starting. High durability is also assured by various kinds of reliability evaluation. Features of K2AS are outlined below.

THIS PAPER DESCRIBES A NOVEL APPROACH to the design of an engine torque/speed controller. Since all the information necessary to design the controller is obtained directly from a small number of step response tests, the necessity of first producing a control model for the engine is avoided, thus effecting, considerable savings in time and effort. Further, although the independent control of an engine's torque and speed is not trivial, the resulting controller has a simple physical structure which makes the device easy to manufacture and inexpensive. The method of control and the required design stages are all demonstrated using a Ford 1.1 L CVH engine.

Some results of a systematic analysis of important sources of hydrocarbon emissions from a direct injection diesel engine are presented. The following sources are considered and investigated: (1) local over-mixing, (2) poor end of injection, (3) fuel emptying from sac volume. The analysis uses systematic engine experiments and an existing two-dimensional thick evaporating spray model to determine the contribution of various hydrocarbon sources to the total hydrocarbon emissions in the exhaust. The results show that at idle and light load conditions, local overmixing is the major source of hydrocarbon emissions. The amount of fuel over-mixed is directly controlled by mixing rate, ignition delay, and the lean limit of combustion. Mixing rate calculations show that the injection rate shape and nozzle geometry are more important than the physical properties of the fuel in determining the amount of fuel overmixed.

To date there is no universal agreement as to the interaction between fuel type, fuel-air mixture preparation and combustion chamber flow characteristics and their effect on soot formation. A propane fueled modified conical back-mixed steady flow reactor was built in which the fuel and air could be mixed together in varying degrees and reacted in at different mixing intensities. The onset of soot and soot loading were determined qualitatively by a photomultiplier focused on the volume inside the reactor. Increasing the degree of premix from a diffusion flame to a distribution of Φmax/Φavg = 5.0 resulted in increases of 3 to 17 percent of the soot-onset equivalence ratio and decreases in soot loading down to zero. Changes in the mixing intensity from 32.5 sec−1 to 75.7 sec−1 resulted in a change in the soot-onset equivalence ratio from 1.26 to 1.52. Soot loading was found to depend on both the mixing intensity, β, and the average number of mixes per mean residence time, β/α.

A new combustion system for a light duty D.I. diesel engine was developed, and a 3.5 ton payload truck (6.5 ton G.V.W.) equipped with this D.I. diesel engine and this combustion system realized good fuel economy and lower exhaust gas emission. Generally, light duty vehicles have to operate over a wide engine speed range. Therefore application of a D.I. diesel engine to light duty vehicles is difficult because of combustion tuning requirements over a wide engine speed range. Up to now, most of the diesel engines for light vehicles have been of the I.D.I. type. But the D.I. diesel engine has an evident advantage of lower fuel consumption. In these circumstances the authors developed a new combustion chamber shape for a small D.I. diesel engine with turbulence induced intake port and optimum fuel injection equipment. Various combustion chamber geometries were tested and evaluated.