Crankcase, Basic Function - GF01.40-P-1000A
Engine all (4xWD)
Engine all (CAR)
Overview
This document contains information on:
- General
- Function
General
The crankcase (1) is the main component of the long block engine and combines the crankshaft bearing arrangement as well as the cylinder assembly in one housing. The crankcases (1) of the current Mercedes diesel and gasoline engines are made from 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. With a significant weight optimization, the aluminum crankcases (1) has a very high material rigidity that allows for peak combustion pressures of up to 160 bar. The crankcase ventilation system ducts (1.2) running inside the crankcase (1) and/or those for the efficient control of 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 (1) is closed off on the upper side by the cylinder head and to 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. The cylinder walls of the crankcase (1) absorb in this connection the gas forces that arise due to 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 The cylinder liners made of steel or cast iron that have been separately installed so far have been replaced by NANOSLIDE® coatings in the current Mercedes engine model designations. Applied directly to the cylinder bores in the crankcase (1) via the twin-wire-arc-sprayed coating process (TWAS coating), this creates a very thin coating 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 surface that is as smooth as a mirror with an up to 50 percent reduction in the friction between the pistons, piston rings and cylinder barrel (A) as well as a weight saving of several kilograms.
The following engine model designations have cylinder barrels (A) 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 so that it can rotate by the upper crankshaft bearings (4) and/or by the lower crankshaft bearings (3) and bolted to the crankshaft bearing caps (2, 5) at the crankcase (1). Via the circulating coolant, the cooling ducts in the crankcase (1) ensure the dissipation of the heat that arises due to combustion and friction. 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 or in contact with each other in the combustion engine, the crankcase (1) has ducts for the transport of engine oil. The crankcase ventilation system provides a further channel structure. During the compression of the fuel/air mixture, both hot gas and gas contaminated with pollutants enter the crankcase (1) and contaminate 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 (1) supports various auxiliary assemblies such as the alternator, the water pump and the refrigerant compressor and is directly screwed onto the transmission via the timing case.
Open deck design:
The coolant 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 |