NOVEL “C.I” ENGINE

Hawke's Bay Tribune, Volume XXIII, Issue 102, 11 April 1933, Page 4

NOVEL “C.I” ENGINE

GERMAN CONSTRUCTION. A compression ignition engine of a most 'unusual and original type is now being produced commercially by the Junkers factory at Dessau, Germany. It works on the opposed-piston principle, which has been previously employed successsfully in 'Diesel engines, and is primarily intended for use in heavy vehicles. Engines with two, three, and four cylinders in lino are now being fabricated, and by the extensive use of light alloys it has been found possible to obtain a good powerweight ration of about 141 b per developed horse-power. Although that figure is well in excess of tho normal ratio of petrol engines, it is remarkably low. In each cylinder of tho Junkers engine there are two pistons which move in opposition to one another, the lower one being connected to the crankshaft in the customary manner. But on either side of the main throw of the crankshaft are supplementary throws, which are coupled by rods to a crosspiece, which is attached to the upper piston. When both pistons are at the limits of their travel the exhaust gases escape through suitable ports, while air which has been pre-compressed is forced through the inlet ports and ensures thorough scavenging of the gases. The next movement in the cycle of operations is that the pistons approach one another, thus compressing the air in the cylinder to a degree which causes ignition of the oil fuel, which is injected near tho centre point of the cylinder at tho moment when tho two pistons approach their top dead centres. The explosion pressure is high, but the balancing effect between the opposed pistons is such that tho load on tho main crankshaft bearings is not abnormal. The engine works on a two-stroke cycle, and when the pistons which have been forced apart by the explosion of the charge reach the end of their firing strokes the exhaust ports are once again uncovered, compressed air is admitted at the top of the cylinder, and the next compression stroke begins. It is said that the two-cylinder engine develops 60 b.h.p. at 1550 r.p.m. Tho. stroke of the upper piston is shorter than that of the lower. In the case of the engine referred to, it is 96 m.m., as compared with 144 m.m. It is thought that because of its compactness this new Junkers unit will prove to be useful in passenger vehicles where chassis space is a serious factor.