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Technical Paper

ALUMINUM PISTON DESIGN

1920-01-01
200006
The two broad divisions of aluminum pistons from a thermal standpoint are those designed to conduct the heat from the head into the skirt and thence into the cylinder walls, and those designed to partly insulate the skirt from the heat of the piston head. Pistons of the first type seem logical for heavy-duty engines; those of the second type are better suited for passenger-car engines. The objections of wear, piston slap, excessive oil consumption and crankcase dilution are stated as being the same for aluminum as for cast-iron pistons; and these statements are amplified. Piston slap is next considered and, as this can be overcome by using proper clearance, pistons of the second design tend to make this condition easier to meet. Many tests show that when too much oil is thrown into the cylinder bores, tight-fitting pistons and special rings will not completely overcome excessive oil consumption.
Technical Paper

SUPERCHARGERS AND SUPERCHARGING ENGINES

1920-01-01
200007
If at great altitudes air is supplied to the carbureter of an engine at sea-level pressure, the power developed becomes approximately the same as when the engine is running at sea level. The low atmospheric pressure and density at great altitudes offer greatly reduced resistance to high airplane speeds; hence the same power that will drive a plane at a given speed at sea level will drive it much faster at great altitudes and with approximately the same consumption of fuel per horsepower-hour. Supercharging means forcing in a charge of greater volume than that normally drawn into the cylinders by the suction of the pistons. Superchargers usually take the form of a mechanical blower or pump and the various forms of supercharger are mentioned and commented upon. Questions regarding the best location for the carbureter in supercharged engines are then considered.
Technical Paper

ADAPTING ENGINES TO THE USE OF AVAILABLE FUELS

1920-01-01
200017
Some of the salient facts regarding the character of the engine fuel marketed within the past few years are shown in accompanying curves. The desirability of operating present-day experimental cars with fuel that is the equivalent of fuel that will probably be generally marketed two years hence is stated and various methods of meeting the fuel problem are then examined. A dry fuel mixture is desired to prevent spark-plug fouling, to improve engine performance in cold weather and to minimize lubricating oil contamination by fuel which passes the pistons. Various methods of obtaining a dry mixture are then discussed, leading to a detailed description of the construction and operation of a device specially designed to accomplish such a result more successfully.
Technical Paper

COMMENTS UPON FUELS, LUBRICANTS, ENGINE AND PISTON PERFORMANCE

1920-01-01
200019
The comments the author makes regarding fuels, lubricants and engine and piston performance are suggested by pertinent points appearing in papers presented at the 1920 Annual Meeting of the Society. A list of these papers is given. The subjects upon which comments are made include salability of a car, engine balancing, pressure and chemical constitution of gasoline at the instant of ignition, the use of aluminum pistons, the success attending the various departures from orthodox construction, gasoline deposition in the crankcase and cleanness of design, as stated by Mr. Pomeroy; the performance of a finely atomized mixture of liquid gasoline and air and the contamination of lubricating oil by the fuel which passes the pistons, as discussed by Mr. Vincent; the dilution of lubricating oil in engine crankcases and the saving that can be effected by its prevention, as mentioned by Mr. Kramer; and tight-fitting pistons and special rings as presented by Mr. Gunn.
Technical Paper

PISTON-RINGS

1920-01-01
200075
The free, resilient, self-expanding, one-piece piston-ring is a product of strictly modern times. It belongs to the internal-combustion engine principally, although it is applicable to steam engines, air-compressors and pumps. Its present high state of perfection has been made possible only by the first-class material now available and the use of machine tools of precision. The author outlines the history of the gradual evolution of the modern piston-ring from the former piston-packing, giving illustrations, shows and comments upon the early types of steam pistons and then discusses piston-ring design. Piston-ring friction, the difficulties of producing rings that fit the cylinder perfectly and the shape of rings necessary to obtain approximately uniform radial pressure against the cylinder wall are considered at some length and illustrated by diagrams.
Technical Paper

IGNITION FROM THE ENGINEMAN'S VIEWPOINT

1920-01-01
200071
Ignition is discussed in a broad and non-technical way. The definition of the word ignition should be broad enough to include the complete functioning of the ignition apparatus, beginning from the point where mechanical energy is absorbed to generate current and ending with the completion of the working stroke of the engine. The ignition system includes the mechanical drive to the magneto or generator and the task imposed on the system is by no means completed when a spark has passed over the gap of the spark-plug. Ignition means the complete burning of the charge of gas in the cylinder at top dead-center, at the time the working stroke of the piston commences. The means employed to accomplish this result is the ignition system. In the present-day type of gasoline engine a spark produced by high-voltage electricity is almost universally used for ignition. This high-voltage electricity is produced by a transformer.
Technical Paper

USE OF ALUMINUM IN PRESENT AND FUTURE MOTOR CARS

1920-01-01
200038
Although aluminum is the most abundant metal in the earth's crust, it was not until the early eighties that means were discovered for reducing it from its ores in such quantities and at such cost as to make it a commercial possibility. The world immediately began to find uses for this material. Two groups developed; one, assuming for aluminum properties that it did not possess, thought that it would in time replace all other metals; the other, which, reacting from the first-mentioned view due to failures and disappointments, thought it had little use. It was afterward realized that much research was necessary to make aluminum a really commercial metal. One of the main aims of the automobile engineer is to obtain lightness combined with proper strength. The paper deals with decreasing the weight of automobiles by more extended use of aluminum alloys. The physical properties of aluminum are described in considerable detail and its varied uses are enumerated.
Technical Paper

FACTORS INVOLVED IN FUEL UTILIZATION

1920-01-01
200060
From a laboratory examination of the controlling relationships between carburetion and engine performance still in progress, the general conclusions so far reached include fuel metering characteristics, the physical structure of the charge, fuel combustion factors and details of engine design and manufacture. In every throttle-controlled engine, the variation in fuel metering for best utilization is inversely functional with the relative loading and with the compression ratio, but the nature of the fuel leaves these general relationships undisturbed. The physical structure of the charge influences largely the net engine performance and the order of variation of the best metering with change in load. Perfect homogeneity in the charge is theoretically desirable but entails losses in performance.
Technical Paper

A MODIFIED DESIGN OF CLASS B TRUCK ENGINE

1919-01-01
190031
THE design of a modification of the Class B Government standardized truck engine is presented, the principal object being a saving in weight without sacrificing either durability or safety factors. The crankcase design is rigid, but the metal is distributed so that the weight will be a minimum. The crankshafts are made of chrome-nickel steel of an elastic limit of 120,000 lb. per sq. in., which further carries out the idea of durability with low weight. The connecting-rod length is slightly more than twice that of the stroke, and this, with light-weight pistons, obviates vibration, without adding weight to the engine on account of increased cylinder height. The flywheel and bell-housing diameters were selected with a view to securing enough flywheel weight for smooth running without increasing the engine weight materially. All-steel supports reduce breakage of arms to a minimum. The manifolds are carefully designed to give economical performance, even with low-grade fuels.
Technical Paper

BURNING KEROSENE IN TRACTOR ENGINES

1917-01-01
170031
The author states as his object a review of what has been done and what must be done to make tractors successful in operating on low-grade fuels, especially kerosene. He takes up in order the four principal methods in common use of applying heat to vaporize kerosene, pointing out the advantages and disadvantages of each method and of its modifications. The author then cites various experiments with different types of carbureters in burning kerosene, drawing at length upon his own experience in this connection. He cites difficulties with gas distribution, manifold condensation, pistons and spark-plugs and points out that carbureter design is inseparable from considerations of tractor engine and manifold design. That better progress has not been made in the past in developing kerosene-burning tractor engines is stated to be largely owing to the fact that there has not been sufficient cooperation between engine and carbureter manufacturers.
Technical Paper

SOME ESSENTIAL FEATURES OF HIGH SPEED ENGINES

1917-01-01
170004
The author outlines methods for producing high-speed engines with high mean effective pressure and gives data resulting from several years' experimental work. He discusses the desirable stroke-bore ratios; valve area, weight, dimensions, location and timing; compression ratios; ignition requirements; and the location and means for operating camshafts and other valve-actuating mechanism. Data are given regarding the best material and dimensions for pistons and the desirable number of rings. The physical characteristics of alloy steel desirable for use in connecting-rods are mentioned. Similar data, including dimensions and factors controlling the construction of the crankshaft and its bearings are included. The relation of the inertia stresses set up by reciprocating parts to those due to the explosion and compression pressure on the piston head is indicated, and the maximum total stress deduced.
Technical Paper

PROBLEMS IN HIGH-SPEED ENGINE DESIGN

1916-01-01
160023
The author outlines in a general way the relation of car performance to modern engine development. He considers particularly weight reduction and torque performance of high-speed engines, giving the undesirable characteristics attending the increased torque range gained by higher speed. He next discusses the relation of torque to total car weight, to acceleration and to hill-climbing ability and suggests a method of determining the value of a car in terms of its performance ability. The author holds incorrect those systems in which the amount of lubrication is in proportion to speed only; and in which oil for crankshaft and crankpin bearings must cool as well as lubricate them. He shows a system designed to solve these oiling problems. Static, running and distortion balance of a rotating mass are defined by the author, who shows how they apply to a large number of types of crankshafts.
Technical Paper

Optimisation of Diesel Engines Converted to High Compression Spark Ignition (SI) Natural Gas Operation

1800-01-01
871149
There is a strong interest around the world in natural gas as an alternative fuel. This paper is concerned with the option of converting diesel engines to spark ignition operation. Although this may appear to be an outrageous thermodynamic action, it is preferable to using natural gas in a low compression gasoline engine conversion. An investigation is described in which engine maps were produced for a 5.6 litre direct injection diesel engine converted to CNG. The diesel operating characteristics have been compared with those of the spark ignition conversion at compression ratios of 18:1 (the original diesel value), 15:1 and 13:1. Detailed data are presented for the 15:1 compression ratio. These test results are supplemented by results for other diesel conversions. The use of these engines in bus fleet operations is also discussed.
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