REMARKABLE ENGINE

Hawera Star, Volume LII, 19 November 1932, Page 12

REMARKABLE ENGINE

CLEVER DIFFERENTIAL STROKE. “The Motor” contains an account of a clever differential stroke engine constructed'by a. working mechanic in Paris, M. Raymond Jaupin. ' An internally toothed ring in the enlarged big end of each connecting rod engages with teeth out in the crank pin, ano the rotation of the big end is guided by side plates which turn freely. The centre of the big end is thus rendered eccentric to that of the pin, and ai. a. result the centre of the big end traces out a curious trefoil curve while the crankshaft makes two revolutions. The piston, instead of making four equal strokes,, is caused to move through short induction and compression strokes, an extremely long powei stroke and an even longer exhaust stroke. The stroke of the piston on the induction stroke is actually 30 mm., whereas on the power stroke it moves through 80 mm., the expansion of the gases being used right up to the limit. On the exhaust stroke the piston rises right to the top of the , combustion chamber, getting rid of all vestiges of burnt gas. Practical results obtained appear to be remarkably good. Although the normal engine speed has been raised from 2600 to 4500 r.p.m., there is no excessive vibration and the engine keeps remarkably cool, so cool, indeed, that M. Tau pin has dispensed with radiator and water circulation and adopted air cooling. A fan mounted in a cowling fitted to the ordinary water intake on the cylinder block directs air into the jacketing. This somewhat primitive arrangement seems to work quite well, and was adopted simply because the engine ran too cold with water in the jacket. ■ , The engine, as will be gathered from the above, is a converted petrol engine from an old car. M. Jaupin, when the article was published, had not been able to obtain' bench tests, owing to the limited means at his disposal, but on the road lie seems to have treblecl tlie mileage obtainable per gallon of fuel consumed. The compression ratio is only 3 to 1, and M. Jaupin considers it should be raised to' 5 to i in order to obtain the greatest efficiency. When the engine was examined by a member of the staff of “The Motor” it was fitted with a short exhaust pipe, seme three feet in length, and there was no silencer. Nevertheless, the engine was quite quiet arid one could scarcely feel the puffs of gas when the hand was placed close to the end of the pipe.