GB575099A - Improvement in or relating to internal combustion engines - Google Patents

Abstract

575,099. Arrangement of sparking- plugs. FOWLER, G. B., and TOEWS, G. P. Oct. 18, 1943, No. 17118. Convention date, April 10, 1943. [Class 7 (ii)] An internal-combustion engine has at least three spark-plugs in each cylinder, two being located at positions 1, 2, Fig. 1, between the inlet valve I and exhaust valve E, while at least one of the others is located at 3 near the inlet valve and is independently controlled as to its time of firing. The plug 3 is fired slightly before the other two. By this arrangement, three flame fronts are obtained and the final combustion usually accompanied by some detonation occurs at the central part of the cylinder as shown by cross-hatched area. In the normal arrangement with two opposed plugs per cylinder, Fig. 4, the flame fronts which are distorted as shown by the influence of the hot exhaust valve, result in a final combustion area located at the side of the cylinder. The invention may also be applied to combustion heads having four valves, Fig. 2, the opposed plugs 1 and 2 being as before fired simultaneously and the plug 3, located between the inlet valves 1 being fired slightly before the other two. The plugs may be arranged in the head of the combustion chamber instead of in the side as shown in Fig. 2, or the plug 3 only may be in the side. In one embodiment, Fig. 7, an engine having three plugs per cylinder arranged as above described has independent magnetos M<1> ... M<3>, each with its own timing control, for the three sets of plugs. In the case of an engine provided with two plugs located as in Fig. 5, two additional plugs making four in all would be required to obtain a single detonation area near the centre of the head. In order to accommodate the three plugs, the head is preferably of flat type (Fig. 1a). The invention enables a compression ratio of 14 : 1 to be used, giving increased power with decreased fuel consumption per b.h.p./hour.