After having exhausted themselves in doing work the gases pass out into a regenerator, which communicates their heat to the air for admission. The valves are actuated by a horizontal shaft placed above the cylinders; the cams are three in number corresponding to three valves, of which two regulate the admission of gas and air to a chamber in which they are mixed. The third valve opens the exhaust. This arrangement is not unlike that adopted by MM. Forest and Gallice for their marine oil engines.
The cylinders are surrounded by water jackets for cooling purposes, aided by air which can enter the front end when the piston is moving in its backward stroke. The hottest portion is therefore that situated at the valve end, and in which the explosion takes place. This portion is surrounded by a closed chamber forming a boiler, where steam is formed for use in the gas plant; the steam is superheated in a spiral coil placed on the top of the gasogene. As we have already stated, this system of gas production avoids the ammoniacal products, which are a constant source of trouble in other engines. The drawback lies in the compressor, which uses up about one-third of the indicated power, but the speed is exceedingly constant, and averages about 175 revolutions per minute. The consumption of gas is not very high, probably owing to the amount of heat which is absorbed from the waste gases, usually lost. A number of other engines exist of a similar type to the Gardie motor, such as the Shaw, Woodburg, Crowe, Buchett, and others, which cannot, however, consume poor gases, and which have not any distinguishing features worth mentioning.
Bénier motor gasogene (Figs. 49 and 50).—We have described the Bénier gasogene, and we will now complete the description by a short notice of the motor associated with it. This motor works on the Dugald-Clerk cycle, and in general arrangement is not unlike the Dugald-Clerk motors. A special compressing cylinder is provided cast in one with the motor cylinder, and the cranks are set at 90° degrees apart from one another. The pump is double, with two pistons coupled tandem-wise in the same cylinder. One of these draws in the air and the other forces the gas into the gasogene. The air and gas thus conducted by different paths reach the mixing chamber placed behind the motor cylinder and provided with a valve. The motor cylinder has exhaust ports perforating the walls, and which are uncovered by the piston when it has moved through five-sixths of the forward stroke. It remains open during the remaining sixth and the first sixth of the return stroke. At this moment the two piston pumps have forced into the cylinder the air and gas which they contain. The mixture enters through a valve and a perforated plate, which thoroughly mixes them in the cylinder. During the return stroke the piston, having closed the exhaust ports, compresses the explosive mixture till the end of the stroke. Ignition then takes place, and the explosion drives the piston forward, and the products of combustion escape to the air directly the exhaust ports are uncovered by the piston.
Figs. 49, 50.—Bénier Engine and Gas Plant (sectional plan and elevation).
By this arrangement it might happen that the explosive mixture introduced into the cylinder might escape by the open exhaust valves. M. Bénier has obviated this difficulty by a novel device. Pure air is first admitted, driving out the products of combustion; the explosive mixture which follows is only admitted when the ports are closed. This result is obtained by properly regulating the supply of air and gas from the pump. One explosion therefore occurs in every revolution.
The Bénier engine is constructed in sizes up to 100 horse-power, and also smaller ones of a few horse-power. A 5 horse-power motor consumes 800 grammes of anthracite per horse-power hour: this result is very remarkable, because great difficulty has been found in working these small engines at all with poor gas; the gas generator seems to work badly when its dimensions are so small. A 15 horse-power motor only consumes 600 grammes per horse-power hour. The Bénier combined plant shown in Figs. 49 and 50 has received a most flattering reception on the Continent, and there is good reason to believe that it will be very much more widely used in the future. We close this chapter with a table setting forth the relative merits and economy of a number of motors.
| Type of Engine. | Nature of Fuel. | Power of the Engine. | Consumption of Fuel. | Consumption per horse-power hour. | Cost per horse-power hour, pence. | Trials conducted by |
|---|---|---|---|---|---|---|
| Lenoir (1860) | Coal gas | ·9 | 2400 litres | 2700 litres | 9 | Tresca |
| Hugon (1866) | ” | 2·07 | 5400 ” | 2600 ” | 8·5 | ” |
| Langen and Otto (1867) | ” | ·46 | 660 ” | 1380 ” | 4·5 | ” |
| Wittig and Hees (1881) | ” | 4 | 4960 ” | 1240 ” | 3·5 | Brauer |
| Koerting-Lieckfeld | ” | 2·18 | 2700 ” | 1275 ” | 3·7 | Schettler |
| Otto | ” | 8·34 | 9500 ” | 915 ” | 2·8 | Allard and Potier |
| Dugald-Clerk (1884) | ” | 11·6 | 9700 ” | 877 ” | 2·5 | Sterne |
| Lenoir (1885) | ” | 2 | 1320 ” | 655 ” | 1·9 | Tresca |
| Simplex (1885) | ” | 9·41 | 5580 ” | 593 ” | 1·1 | Witz |
| ” ” | Dowson gas | 3·66 | 6040 ” | 3300 ” | ·7 | ” |
| Lenoir (1885) | Carburetted air | 4·15 | 2·7 ” (petroleum) | ·65 ” | 4·5 | Tresca |
| Benz (1885) | Coal gas | 5·1 | 3600 litres | 707 ” | 1·4 | ” |
| Atkinson (1888) | ” | 9·48 | 6000 ” | 618 ” | 1·3 | Society of Arts |
| Crossley(1888) | ” | 14·74 | 10,800 ” | 765 ” | 1·5 | ” ” |
| Griffin (1888) | ” | 12·51 | 9500 ” | 786 ” | 1·5 | ” ” |
| Charon (1889) | ” | 4·17 | 2210 ” | 530 ” | 1·1 | Witz |
| Forest (1890) | Petroleum spirit | 16·67 | 7 kilg. 400 | 458 grms. | 3 | Martin |
| Niel (1891) | Coal gas | 3·75 | 1250 ” | 402 litres | ·8 | Witz |
| Simplex (1889) | Poor gas | 75 | 191 cub. met. | 2370 ” | ·7 | ” |
| ” (1893) | ” | 220 | 110 kilg. (anthracite) | 500 grms. | ·3 | Leblan |
| Lenoir (1891) | Coal gas | 6 | 4260 | 710 litres | 1·5 | Lencauchez |
| Charon (1892) | ” | 7·5 | 4380 | 586 ” | 1·2 | Chauveau |
| Priestman (1890) | Daylight oil | 7·7 | 3 kilg. | 385 grms. | 1·7 | Unwin |
| ” (1891) | Russoline | 6·7 | 2 kilg. 700 | 428 ” | 1·9 | ” |
| Crossley (1892) | Dowson gas | 148 | 415 kilg. (anthracite) | 280 ” | ·2 | Dowson |
| Atkinson (1892) | ” | 16·7 | 6·6 kilg. | 455 ” | ·3 | Tomlinson |
| Schleicher-Schum | Poor gas | 92 | 55 ” | 596 ” | ·32 | Spanglon |
| Trusty | Petroleum (ordinary) | 4·3 | 1·83 ” | 440 ” | 2·2 | Beaumont |
| Delamare-Deboutteville (1894) | Lencauchez gas | 62 | 37 ” | 603 ” (cheap coal) | ·2 | Bourdon |
| Campbell (1895) | Petroleum (ordinary) | 6 | 2·4 ” | 400 grms. | 2·5 | ” |
The price of fuel has been calculated from prices current at the dates given.