1908 Edition Sent to us by Richard D. Hamp, 1772 Conrad Avenue, San Jose, California 95124-4501
Before the commencement of his experiments on oil engines, Emile Capitaine had already gained considerable experience in the design of gas engines, to the development of which his work in no small degree contributed. His first oil engine patent dates from 1879, and from that time until 1886, when a further patent was granted, he carried out a continuous series of laborious and costly experiments with a view to devising an engine which would run satisfactorily on ordinary lighting petroleum having a density of about 0.88.
Good results were obtained from the early engine, which worked without either flame or heating tube; but it was found necessary to give each time a full charge, or at the least 75 percent. Otherwise, if the charge were too small or omitted, the vaporizer chamber, which was maintained at the necessary temperature by the repeated explosions, became chilled to too great an extent. From this it will be evident that the engine could only work under certain conditions. Numerous experiments were also made with a view to arriving at a type of engine which would work equally efficiently at full and low loads, the consumption of oil being proportioned to the power developed. Two new patents were obtained for a system of regulating the temperature, but the gear was of too complicated a nature, and finally, after much experimenting, Capitaine adopted the lamp heating system, which has given very good results. In this later type of engine the vaporizer remained always in communication with the interior of the cylinder, but its form was such that even when heated to redness premature explosion of the mixture did not take place, and the formation of carbonaceous deposits on the inner surfaces was entirely avoided.
In the Capitaine engine of 1892-1893, although a vaporizer lamp is provided, it may be dispensed with, as the engine can also work on the pneumatic system employed in the 1886 type, with, as before, the conditions that the charge must not be less than 75 percent of the full amount, and that the number of explosions must not be reduced. Considering the uniformly good diagrams that are obtainable from the Capitaine engine without a heating lamp, when the temperature of the vaporizer varies within considerable limits, all that is necessary for successful working is to enclose the vaporizer and to allow it to retain as much as possible of the heat of each explosion. Above all, it is essential to protect it during the suction period from the contact of cold air or gas at a lower temperature. By observing these conditions Capitaine has succeeded in devising a type of engine which gives excellent results and does not involve the use of a heating lamp. By carefully coating all the surfaces with refractory non-conducting materials, he has also succeeded in placing the vaporizer within the combustion chamber itself. In this arrangement, which forms the subject of a separate patent, a quantity of hot and expanded gas is allowed to pass into the vaporizer by means of a small valve, which opens at the end of the expansion stroke, and closes immediately thereafter, when the large exhaust valve is opened. To start the engine from the cold condition the vaporizer must first be heated by means of a hand lamp for two or three minutes.
The characteristic features of the engine may be summarized as follows:
1. It dispenses with a heating lamp or other similar gear; 2. Only two or three minutes are required for the starting of the engine, owing to certain features in the design of the vaporizer: (a) the limited admission of air; (b) its inclusion in the combustion chamber; (c) the use of non-conducting coverings; and (d) the use of the very hot gases for heating it; 3. The vaporizer is not cooled during the suction stroke; or when explosions are missed for the purpose of economically regulating the speed.
This engine is the same as that already described in the section devoted to gas engines, with the addition of a special type of vaporizer, which enables a combustible mixture of air and oil vapour to be used instead of coal gas. The vaporizer consists of a chamber divided by vertical walls into four canals, through which the flame from the lamp passes upwards to the exit chimney at the top, while a single-acting pump driven by a lever forces a stream of air through a hot spiral passage encircling the lamp chimney. After its passage through the spiral the heated air comes into contact with the oil, a portion of which is entrained and carried over. Instead of the wick customarily used in the heating lamps of other engines the system of feeding the oil by means of a small pump has been adopted, and after the engine is well started the lamp is not required, as the heat of the explosions maintains the temperature of the vaporizer. Various modifications and improvements of this engine have been made since its first appearance, the principal being the reduction of the time required for the preliminary heating of the vaporizer when starting the engine, and the simplification of the valve mechanism. Fig. 384 illustrates a moderate-power type of Crossley oil engine in which any grade of refined or crude petroleum may be readily burned, and other examples are given in Figs. 385 and 386.
Engines of very similar construction are also manufactured by Messrs, Crossley for burning petrol or benzene, as in Fig. 387, which shows an entirely self-contained portable engine of 3? B.HP.