An Interesting New Engine at the Paris Show.
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By Our Paris Representative.
From the standpoint of the motor user, one et the most interesting exhibits at the annual agricultural show which opened in Paris last week was an entirely new type
of "valveless" stationary motor. Among French agriculturists the use of small stationary motors for driving various types of farm machinery has enormously increased during the past two or three 3 ears, thanks largely to the efforts of pro,. incial motor clubs and various agricultural societies. The most popular type is the single-cylinder vertical, either fixed or mounted on a trolley to allow it to be moved from place to place, according to the work to be undertaken.
The new type, which is the invention of MM. Dubois and Rousseau, enters into this class, but is distinctive by reason of the use of a reciprocating distributor in place of the usual poppet valves. The motor has a single-cylinder with a bore of 100 mm. and a piston stroke of 150 mm. The cylinder is mounted on a very substantial base, the lower portion of which forms an oil reservoir and carries a large-diameter flywheel and a single pulley. At the top of the combustion chamber is a special distributor consisting of a cylinder having a large portion of its face cut. away and the two remain ing cylindrical end portions cut through, in similar manner to a piston ring, in order to make it extensible. This distributor, being mounted in the head of and across the combustion chamber, -normally covers two elongated ports which are respectively for admission and exhaust. On being rotated in one direction it will uncover one of the ports and mask the opposing one, and on being rotated in the opposite direction the process will be reversed. In its central positions, corresponding to compression and firing strokes, the two ports are covered and a gastight chamber is assured by reason of the extension of the distributor. The operation will be readily understood by
reference to the accompanying line illustration.
This new engine, after having been adopted by two French firms for pleasure
cars, is about to be applied very extensively to industrial uses; it will be used with various kinds of fuel, and, owing to its extreme simplicity, there is every promise of its very considerable success. The design makes it possible to obtain large valve areas; an the example which is now exhibited the ports are almost equal to the diameter of the cylinder, being 90 ram. in length, and having a depth of 10 mm. During two out of the four strokes—compression and firing—the distributor is immobile in the cylinder head, whilst its total movement is only 40 degrees.
The lubricatien of the distributor is provided for by a wick feed in the head of the cylinder, it being declared that the
amount of lubricant dripping through is quite sufficient for the needs of this component. The motor is cooled by thermosyphon circulation, there being a good quantity of water on the head of the cylinder ; the distributor is thus in contact with a water-cooled surface.
The distributor is merely a loose fit in the cylinder walls without the use of a special bearing. There are two opposed openings, of suitable diameter, in the cylinder walls, through which the distributor is passed, the ends being closed by vistas, each of which is screwed down on to a couple of projecting studs. One of these plates carries the sparking plug in its centre the opposite one receives the driving mechanism. Thus, to withdraw the distributor, it is only necessary to
onczew two nuts, take off the cap carrying the plug, and pull the distributor out, -without in any way disarranging the tini. ing. To change a distributor would thus Gaccupy no more time than to take out a parking plug. On the aide of the cylinder opposite to that on which the plug is mounted, the cap receives a metal disc with a cone seating, from the inner face of which a short stud projects. and this engages in a channel within the distributor. On the outer face a central stud supports a short Lever; this receives the upper end of a vertical pushrod having a positive upand-down motion by means of a cam and a coil spring. On the upward movement of the pushrod the distributor is rotated until it uncovers the exhaust port ; its return to close the exhaust and open the intake is assured by the coil spring withie the pushrod eniae. With a view to simplicity, the designers have mounted the front main bearing in a bolted-on end plate. On this being taken down, access is secured to the motor base. The peojecting end of the main shaft carries a governor operating a butterfly valve in the intake pipe. Instead of a positive drive to the magneto, mounted on a platform to the right of the motor, the main shaft carries an eccentric and a trip gear clearly shown in one of the illustrations herewith.
This motor is at present fitted with a French make of paraffin carburetter, but according to the designers it will shortly be supplied with one of their own make.