Whitman Motor-Car Principles The Gasoline Automobile

1. Auflage 2023
ISBN: 978-3-98826-298-1
Verlag: OTB eBook publishing
Format: EPUB
Kopierschutz: 0 - No protection

E-Book, Englisch, 178 Seiten

Reihe: Classics To Go

Motor-Car Principles: The Gasoline Automobile is a non-fiction book written by Roger B. Whitman and first published in 1917. The book is a comprehensive guide to the principles of gasoline-powered automobiles, and covers a wide range of topics related to their design, operation, and maintenance. The book begins with an overview of the basic principles of the internal combustion engine, including the various components that make up the engine and the processes by which they work together to convert fuel into mechanical energy. It then goes on to discuss the various types of gasoline engines and their different characteristics, as well as the principles of fuel delivery and combustion. Whitman also provides detailed explanations of the various systems and components that make up a modern automobile, including the transmission, brakes, suspension, and electrical systems. He covers everything from the design and operation of the engine, to the principles of steering and handling, to the principles of fuel efficiency and emissions control. Throughout the book, Whitman emphasizes the importance of proper maintenance and repair of automobiles, and provides detailed instructions for performing a wide range of maintenance tasks, from basic tune-ups to more complex repairs. He also includes a number of helpful tips and tricks for improving the performance and reliability of gasoline-powered automobiles. Motor-Car Principles: The Gasoline Automobile is a valuable resource for anyone interested in the principles and mechanics of gasoline-powered automobiles. Whether you are a professional mechanic, a car enthusiast, or simply someone who wants to better understand how your car works, this book provides a wealth of detailed and useful information.

Autoren/Hrsg.

Whitman, Roger B.

Leseproben

CHAPTER I

GASOLINE ENGINE PRINCIPLES
The action of a steam, gasoline, or hot-air engine depends on the principle that when air or other gas is heated it expands, and that if it is confined in a space that will not permit it to expand, in striving to do so it creates pressure against all parts of the chamber in which it is contained. The more a gas is heated, the more it will expand if it is free to do so, and if not free, the greater will be the pressure that it will exert in striving to expand. Pressure may thus be generated by heat, and following along similar lines, heat may be produced by pressure, for when the pressure of a gas is increased by compressing it, or forcing it to occupy a smaller space, the gas will become heated. The reverse is also true, that when a gas is cooled, its volume is reduced, which reduces the pressure that it exerts; similarly, reducing the pressure by permitting the gas to expand reduces its temperature. To state these principles in another form, to create pressure in a gas it must either be heated or compressed into a smaller space, and to reduce its pressure it must either be cooled or permitted to expand. The action of a locomotive, the most familiar type of steam engine, is no mystery, and the production of steam in the boiler, its passage to the cylinder, and the application of its steady pressure against first one side of the piston and then the other, resulting in the turning of the driving wheels, are well understood. Water being converted into steam in the boiler, pressure is created because of the tendency of the steam to expand, but the only place in which it may expand is the cylinder, where in so doing it moves the piston. Fig. 1.—Engine Actions. A gasoline engine is similar to a steam engine in that its piston is moved by the pressure exerted by a heated and expanding gas; it is different in that the pressure is produced inside of the cylinder by the combustion of an inflammable mixture of gasoline vapor, instead of being generated in a boiler away from the cylinder. The heat of the combustion creates great pressure, and as the piston is the only part that can give before it, it is moved from one end of the cylinder to the other, this motion being utilized in the turning of the crank shaft. The combustion, which is so rapid that the generally accepted term for it is explosion, can occur only after the mixture has been drawn into the cylinder, and so prepared that it ignites quickly and burns completely, with the object of obtaining the greatest possible heat from it in the shortest possible time. In order that one explosion may be followed by another, the burned and useless products of combustion must be expelled to make place for a fresh charge of the inflammable mixture. These successive events, forming a cycle, must be performed as long as the engine runs, and the constantly changing pressure in the cylinder due to the movement of the piston allows a fresh charge to enter, prepares it, and expels the products of combustion after the pressure that they have exerted has been utilized. While in the great majority of steam engines the steam acts first on one side of the piston and then on the other, in an automobile gasoline engine the pressure is exerted on only one side, the combustion of the mixture taking place between the piston and the closed end, or head, of the cylinder. The other end of the cylinder is open, and the piston slides between the ends, its movement from one end to the other, called a stroke, corresponding to a half revolution of the crank shaft. Gasoline engines are divided into two classes, according to the number of strokes of the piston that are necessary to accomplish the cycle; in the most usual type, four strokes are necessary, the class being called the four-stroke-cycle, or four-cycle, in distinction to the two-stroke-cycle, or two-cycle, in which but two strokes are necessary. Of the five events that compose the cycle, three (the inlet, during which the fresh mixture enters the cylinder, its compression or preparation, and the exhaust of the burned gases) are performed by the piston; during the power event the piston is moved by the pressure resulting from the combustion, while the combustion event is due to an outside source. In the four-cycle type of engine, which is in almost universal use for automobiles, the events are considered with reference to the movement made by the piston during which they are performed, and may be called the inlet, compression-combustion, power, and exhaust strokes. In order that the engine may continue to run, it is obvious that the events must be performed in the correct order, and that the failure of one will affect all the others. During the inlet stroke, a charge of fresh mixture enters the cylinder as the piston makes an outward stroke from the closed toward the open end. When the piston makes the following inward stroke, the mixture is compressed and combustion occurs, the pressure from which drives the piston outward on the power stroke. This is followed by another inward stroke, which pushes the burned gases out of the cylinder. It will be seen that power is developed during only one stroke of the four, the other three being required in the preparation for the following power stroke. The movement of the piston over these three dead strokes is secured by attaching to the crank shaft a heavy fly wheel, the momentum of which, acquired during the power stroke, keeps the crank shaft revolving and the piston in motion while the events are performed. Fig. 2.—Gasoline Engine Cycle. The space between the piston and cylinder head in which the combustion occurs is called the combustion space, and the inlet and exhaust valves open into it, the first being that by which the fresh mixture enters, and the second that by which the products of combustion escape. The device for igniting the mixture projects into the combustion space, and the means of ignition in universal use for automobile engines is an electric spark. INLET STROKE
During the stroke (Fig. 2), the piston is moved outward by the crank shaft, which is revolved either by hand or by the momentum of the fly wheel. This movement increases the size of the combustion space, thereby reducing the pressure in it, and the higher pressure of the atmosphere outside of the cylinder will force fresh mixture into the combustion space, the inlet valve being open to admit it. If the piston moves slowly, the mixture will be able to enter fast enough to keep the pressure in the combustion space equal to that outside, but at the high speed at which a gasoline engine is run the piston will reach the end of its stroke before a complete charge has had time to enter, so that the pressure in the combustion space will still be below that of the atmosphere. If the inlet valve closed at this point so that no more mixture could enter, the combustion of the partial charge would result in a lower pressure than would be possible with a full charge; the inlet valve should therefore remain open until the piston reaches the point of its next inward stroke at which the pressure in the cylinder equals that outside. COMPRESSION-COMBUSTION STROKE
The compression and the combustion of the charge occur during the next inward stroke of the piston. The period between the bringing together of the liquid gasoline and air and its admission to the cylinder is too brief to secure perfect combination, and the mixture that results is not satisfactory. A portion of the air will not have been able to come into contact with the gasoline, and much of the liquid will not have been vaporized; what passes into the cylinder consists of pure air, liquid gasoline, and a more or less perfect mixture of the two. The combustion of this would be slow and incomplete, resulting in loss of power and waste of fuel. In order to render the mixture more perfect, advantage is taken of the heat that is produced by compression; the inward stroke of the piston raises the temperature of the mixture by compressing it, the heat rendering the gasoline more volatile, and the compression forcing it into combination with the air. Even this does not result in the formation of a perfect mixture, for the period is too short to effect it. The failure of an engine to deliver full power may often be traced to this condition, for the air and gasoline vapor, instead of being thoroughly combined and mixed, will be in layers, so to speak, and the combustion will be slow and uneven. Future development of the internal combustion engine will no doubt eradicate this, to the increase of efficiency and economy. The charge of inflammable mixture can produce a certain amount of heat, and the more rapidly and completely this heat is obtained, the greater and more sudden will be the rise in pressure. The pressure will be greater when the mixture is contained in a small space than when in a large, and as the combustion space is smallest when the piston is at its inmost point, the greatest pressure will be obtained if combustion is complete at this point. If the combustion of the mixture were instantaneous, it should be ignited at this point; but even though very rapid, it nevertheless burns slowly enough to make it necessary to ignite it sufficiently before the end of the stroke to have the combustion complete as the piston comes into position to move outward. The instant at which the mixture must be ignited in order to...