Crankcase, Basic Function - GF01.40-P-1000A
Engine all (4xWD)
Engine all (CAR)
Overview
This document contains information on:
- General
- Function
General
The crankcase is the main component part of the long block engine and combines the storage of the crankshaft and the group of cylinders in one housing. The crankcases of the current Mercedes diesel and gasoline engines are made of aluminum. Cast with the water-cooled chill casting method, the liquid aluminum cools off more quickly and hardens earlier. This results in a very fine-grit and dense material structure, which leads to very high strength values. In addition, this manufacturing method allows the production of complex exterior and interior geometries. Significantly weight-optimized, the crankcases made of aluminum provide a very high level of material rigidity that permits peak combustion pressures of up to 160 bar. The channels running in the interior of the crankcase for crankcase ventilation or efficient control of the fluids for engine cooling and engine lubrication have a highly complex design.
Example illustration of crankcase M139
Example illustration of crankcase M282
Function
The crankcase is closed off on the upper side by the cylinder head and on the bottom by the oil pan. In combination with the cylinder head, the cylinders form the cubic capacity, which is used for the combustion of the fuel/air mixture. In this process, the cylinder walls of the crankcase absorb the gas forces that arise as a result of the combustion. The cylinder liners made of steel or cast iron that have been separately installed so far have been replaced by NANOSLIDE® coatings in the current Mercedes engine model designations. With the TWAS coating (LDS) applied directly to the cylinder bores in the crankcase, this creates a very thin layer of 0.10 mm to 0.15 mm. Based on an iron-carbon alloy, this results in a micron-grained material structure with very high wear-resistance and microporosity. The result is a smooth surface with up to a 50% reduction in friction between pistons, piston rings and the cylinder barrel as well as a weight saving of several kilograms.
The following engine model designations have cylinder barrels with NANOSLIDE® coating:
- M133; M139; M167; M177; M178
- M254; M256; M282; M276 DELA
- OM654; OM656
Cylinder liners made from cast iron are installed in the following engine model designations:
- M260; M264
- M270; M274
- M278; M279
The crankshaft is mounted in the upper crankshaft main bearing/lower crankshaft main bearing so that it can turn and screwed to the crankshaft bearing caps on the crankcase. Cooling ducts in the crankcase ensure the removal of the heat generated by combustion and friction by way of the circulating coolant. Open deck construction/closed deck construction are special variants of cooling duct structures.
For the efficient lubrication of all component parts that are mechanically moved and in contact in the combustion engine, the crankcase has channels for transporting engine oil. The crankcase ventilation system provides a further channel structure. During the compression of the fuel/air mixture, hot gas contaminated with pollutants enters the crankcase and puts stress on the engine oil.
Carrying along uncombusted fuel remnants, especially during a cold start, causes oil dilution. To counteract this, the crankcase ventilation system guides away the resulting leaked gases to the intake stroke for combustion.
The crankcase holds various ancillary equipment such as the alternator, the water pump and the refrigerant compressor and is screwed directly to the; transmission via the timing case.
The cool ant chamber is open at the top around the cylinders. Coolant flows around the upper cylinder area via this additional space, achieving a higher level of cooling output. The lower rigidity of the open deck construction compensates for the installation of a metal cylinder head gasket.
Closed deck design;
The cover plate is interspersed by smaller ducts for the coolant. This results in high rigidity, which has a positive effect on the durability of highly loaded engines.
| Additional basic functions | |||
| Crankcase ventilation system, basic function | Engine all (CAR) | GF01.20-P-1003A | |
| Crank assembly, basic function | GF03.20-P-1000A |