Water-cooled, multi-cylinder internal combustion engine

Abstract

In a water-cooled, multi-cylinder internal combustion engine, which comprises cylinders and a cooling jacket, the cylinders are connected in the lower region thereof to each other and to the cooling jacket, and crankshaft main bearings consisting of two parts which are mutually connected by means of main bearing bolts, the lower ends of the cylinders are connected to the cooling jacket at a height from the bottom edge of the cylinders corresponding to 0.5 to 0.75 times the cylinder diameter, and downwards from this level the lower cylinder ends are connected to each other but otherwise free and unconstrained, and the threads for the main bearing bolts are arranged at a height from the bottom edges being at least that great as the distance of the connection between the cylinders to the bottom edges. Thereby, reaction forces from the main bearing bolts are transmitted directly to the region above the connection between the cylinders and the cooling jacket or are transmitted through the junction between the cylinders and cooling jacket and distributed to the cylinders and the cooling jacket in that region thereof which is above the junction. The unconstrained lower end of each cylinder is free from reaction forces thus avoiding unacceptable deformation in this region. Also, it is possible to choose a comparatively small working clearance between piston and cylinder which means less noise generation. Moreover, piston rings with lower tensions may be used, which means lower friction and, owing to the drastically reduced liner deformation, also less oil consumption.

Dependencies are inferred from the claim text.