GAS ENGINE 



3438 



GAS ENGINE 



Gas Engine. Instrument for 

 developing power. It is distin- 

 guished from the steam engine by 

 the fact that the heat which is the 

 immediate source of its power is 

 developed in the engine cylinder 

 behind the working piston, which 

 is moved directly by the expansive 

 force which accompanies the de- 

 velopment of the heat. That is to 

 say, the fuel gas is burned 

 directly in the engine cylinder, and 

 not in a separate vessel such as a 

 steam boiler. 



About 1680 the French scientist, 

 the Abbe* d' Hautefeuille, arid the 

 Dutch mathematician, Christian 

 Huygens, both suggested a form 

 of engine in which the power was 

 to be derived from the explosive 

 energy of gunpowder. A century 

 later an English patent was granted 

 to John Barber for what he called 

 an " exploder," in which he pro- 

 posed to explode a mixture of 

 hydrocarbon gas and air, and in 

 that way develop motive power ; 

 and in Barber's specification is the 

 first suggestion of the gas engine 

 of which there is any record. 



A little later a French engineer, 

 Philippe Lebon, suggested the use 

 of coal gas as a source of power ; 

 but it was not until 1860 that 

 another French inventor, Etienne 

 Lenoir, designed a practical engine, 

 of which several hundreds were 

 made both in France and in this 

 country, although it was of only 

 very limited power, and consumed 

 much gas, over 140 cubic feet per 

 horse-power hour. Two years later 



Gas Engine. Typical 4-cycle gas engine. Fig. 1. A, cylinder; B, trunk 

 piston; C, connecting-rod; D, crank; E, crank-pin; F, crank-shaft ; G, fly- 

 wheel; H, framing; J, gas and air inlet valve; K, outlet valve for burnt gases; 

 M, flame slide valve; N, ignition gas flame ; 0, water jacket. Fig. 2. First 

 stage of cycle, drawing in gas and air, a to b in indicator diagram. Fig. 3. 

 Second stage, compression of gases, b to c in indicator diagram. Fig. 4. 

 Firing oi gases, c, d, e of indicator diagram. Fig. 5. Fourth stage, driving out 

 burnt gases, e to a of indicator diagram. See text 



Card 1 



ence to the indicator diagram and 

 Fig. 1. The engine works on what is 

 called a four-cycle, 

 that is to say 

 there is one im- 

 pulse (explosion) 

 in the engine cylin- 

 der to every four 

 strokes of the 

 piston, two for- 

 ward and two back, 



Gas 



indicator diagram, 

 pressure of gases in cylinder. For explanation, see "text 



~b crank. The cycle 

 showing varying is made up of the 



(3) The mixture is exploded, and 

 the piston advances a second time, 

 driven forward by the force of the 

 explosion. This movement is repre- 

 sented by the line c d b, the 

 height of d above the line a b 

 indicating the maximum pressure 

 upon the explosion of the mixture. 



(4) Finally the piston returns from 

 B to A, and drives out as it moves 

 the waste gases resulting from the 



or in two complete combustion of the original charge. 



revolutions of the The fact that only one explosion 

 takes place in every four strokes 

 of the piston or two revolutions of 



another French scientist, Beau de ments : (1) 



Rochas, proposed the adoption of piston advances 



the principle of compressing the from A to B, dra 



mixture of gas and air before ex- ' 

 ploding it in the engine cylinder, 



Cl _.,__]_ M 



following 

 the 



move-- the crank results in a vorv notice- 



and suggested the working " cycle, 

 which has since been generally 



adopted. Improvements were 

 added to Lenoir's design by Dr. 

 Nicholas A. Otto and Eugen 

 Langen, and in 1878 the former 

 embodied the principle of com- 

 pression which had been suggested 

 by Beau de Rochas in a design of 

 engine which was the first to at- 

 tain real success. 



The principle of the Otto engine senting the degre 

 may be readily understood by refer- of compression. 



ing in as it moves 

 the mixture of gas 

 and air. (2) The 

 piston returns to 

 the other end of 

 its stroke, and in 

 doing so com- 

 presses the air and 

 gas. This move- 

 ment is represented 

 by the line b c, the 

 height of c above 

 the line a b repre- 



Engine. Two to seven Brake Hoise Power 

 (B.H.P.) horizontal gas engine 



