Ladder frame of an engine

#The present invention relates to a ladder frame of an engine, and more particularly, to a ladder frame with partition walls defining separate crank chambers.

#Generally, an automobile engine includes a cylinder block having cylinders for reciprocally receiving pistons, a cylinder head for installing cam shafts to actuate suction and exhaustion valves, which are installed in the upper portion of the cylinder block, and an oil pan installed in the lower portion of the cylinder block and containing an amount of oil for lubricating the sliding portions of the engine.

#The cylinder block is classified in accordance with the length of the skirt into either a long stroke type cylinder block or a short/semi stroke type cylinder block. In the long stroke type cylinder block, the oil pan is directly coupled to the bottom. On the other hand, in the short/semi stroke type cylinder block, a bed plate (the case where the main bearing cap is formed integrally) or a ladder frame (the case where the main bearing cap is formed as a separate member) is interposed between the oil pan and the cylinder block.

#The features and advantages of the present invention will be more apparent from the detailed description of the present invention with reference to the attached drawings in which:

#FIG. 1 is a perspective view of the ladder frame of an engine according to the present invention;

#FIG. 2 is a perspective view of the bottom of the ladder frame shown in FIG. 1;

#As shown in drawings, a ladder frame according to an embodiment of the present invention is formed as an essentially elongate rectangular outer block 1 in the case of a 4-cylinder engine. Inside the rectangular outer block 1, three partitioning walls 2a, 2b and 2c are formed equidistantly apart, so as to form four crank chambers 3a, 3b, 3c and 3d.

#On the partitioning walls 2a, 2b and 2c, and on front and rear walls 1a and 1b of the outer block 1, there are formed elongate upward-openings, i.e., main bearing installation parts 4a, 4b, 4c, 4d and 4e, for installing main bearings to support a crank shaft. The outer end of the main bearing installation part 4e of the outer wall 1b is to be connected to the input shaft of the transmission, and is arcuate or almost arcuate so as to dampen noise and vibrations.

#The crank chambers 3a, 3b, 3c and 3d of the outer block 1, respectively, have bottom walls 5a, 5b, 5c and 5d which are not perforated or open, but are completely closed. On the inside surface of the bottom walls 5a, 5b, 5c and 5d, there are respectively formed inclined oil flow faces 6a, 6b, 6c and 6d which become gradually deeper in the revolution direction of the crank shaft. Oil flow faces 6a, 6b and 6c, those of the first, second and third crank chambers 3a, 3b and 3c have oil drain holes 7a, 7b and 7c, respectively, at their ends opening through the block. However, oil flow face 6d, that of the fourth crank chamber 3d is not covered by an oil pan (not illustrated), which is installed under the ladder frame and therefore does not have its own drain hole that opens directly through the block.