NEW DIESEL CYCLE

Wanganui Chronicle, Volume 74, Issue 190, 13 August 1931, Page 9

NEW DIESEL CYCLE

LOW-PRESSURE ENGINE. : * A new and interesting type of Die- 1 sol engine, employing a different cycle c from those already available, ami work- * ing at the remarkably low compression c of 1601 b. per square inch, has been in- Q vented by Mr. G. 8. Edlin, an Auek- 1 land engineer, says “Focus” in the 1 Auckland Herald. A company, known as the New Zealand Edlin-Stewart En L gine Company, Limited, has been form v ed to handle the invention, and an ex ' perimental engine, to be used chiefly for c demonstration purposes and further re 2 search work, has been constructed locaily by Messrs. Johnson and Sons, Par- 1 noil, and has attracted considerable in terest at the company’s workshop, where demonstrations have been given daily. In J 914, Mr. Edlin first conceived the a idea of a balanced petrol engine, in c which the gases* would bo expanded to v a greater extent than had been the i practice previously. He worked spas medically on his idea until 1926, when | he was joined by Mr. H. H. Stewart, another Auckland engineer, who assist- t cd in bringing Mr. Edlin’s design be- \ fore the public. By .1927, an engine i with commercial possibilities had been produced, and a syndicate was formed. 1 An engine suitable to illustrate Mr. Ed \ lin’s design more fully had been con t , structed by 1930, the present company i was formed, and two representatives \ were sent overseas to introduce the new ]■ type of engine. f c Interest in Diesel Types. c The engine first devised by Mr. Edlin was a petrol-burning plant, and it was found that although a great deal of in. ' terest was aroused, engineers were con- s centrating on crude oil development. 1 .Since the interest in this direction was so great, and the engine, which had a definite suitability for burning crude 1 1 oil, would actually work on the Diesei < principle at a compression of 90lb. per c square inch, Mr. Edlin turned his at- 1 tentioas to the devising of an injector 1 of a type suitable for the engine. The c 1 company has now protected the new in \ jector by patents, and has also secured the services of Mr. T. H. Hopkins, a 1 1 Diesel engineer of wide experience. ( The engine at present being demon- 1 strated is built on marine lines. Al- ( though a Diesel, it has no auxiliaries to 1 absorb power, and has a great output 1 coupled with abnormally smooth torque 1 and fine balance. The new features em i bodied in the engine are such as to eliminate the difficulties of the present s day types of Diesel with their compli < cated technique, and make of this en-1 1

gine a Diesel which can be placed in the hands of the ordinary layman. Diesel Engine Principles. Mr. Edlin explained that the present day two-cycle Diesel, known as a con-stant-volume engine, compressed air to a high pressure in the cylinder, resulting in an increase in temperature. When the piston was within a few degrees oi the top of the stroke, fuel oil was sprayed into the hot air, the mixture immediately burned, and the expansion of the gases propelled the piston down ward on the power stroke. At the end of this stroke the exhaust gases were released, and by means of auxiliary pumping apparatus, a charge of new air was blown through the cylinder, with ' the definite purpose of expelling any gas left over after the explosion. The draught of air also helped to cool the cylinder. This was recognised as stan dard practice throughout the world on two-cycle Diesels, aud the more com plete the scavenging, the more eilicieni the engine was considered. After the scavenging, the remaining air iu the cylinder was compressed to approximately 5001 b. per square inch, more oil was injected, and the cycle continued. There were also four-cycle Diesels, known as “full Diesels, ’ Mr. Edlin said. In these, every second rotation of the crankshaft was used for scavcng ing. Cycle of the New Engine. The main difference between the ordinary Diesel described above and the Edlin engine was that iu the latter halt of the exploded gas was retained in the cylinder for purposes of ignition, and also ou account of the additional heat unit it contained, the inventor said. No attempt was made at scavenging, and as a result power-absorbing auxiliaries were not necessary. The present engine is a single-cylinder unit, with both bore and stroke of seven inches. It has a balanced crank-shaft with three cranks. To this is connected the power piston, ■which operates in a stationary water-cooled sleeve, outside of which is a power sleeve connected to the other two cranks. This sleeve is enclosed in an outer water-cooled cylinder. The power sleeve aud the power piston, operating on a 180 deg. crank, permit double expansion of the gases, for as i the piston moves down, the power sleeve travels up, and both forces are transmitted to the crankshaft. The injection device invented by Mr. Edlin specially for the engine embodies a new system, which simplifies starting from cold. The injector super-atoiniscs a charge of fuel oil, and the engine will start at 1601 b. per square inch. The present engine develops 25 h.p. at 500 r.p.m., and its speed range is from 250 to 800 r.p.m. The type lends itself to very light construction, as the whole engine, with the exception of crankshaft, connecting-rods, pistons and sleeves, could well be made of aluminium or some other suitable alloy.