Internal-combustion engines – Frame construction – Horizontal cylinder
Patent
1998-02-04
2000-06-06
Wolfe, Willis R.
Internal-combustion engines
Frame construction
Horizontal cylinder
123 4167, 123195H, 384429, F02F 700
Patent
active
060705620
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Efforts have been made to reduce the weight of multiple cylinder internal combustion engines, particularly in passenger vehicles. Therefore, one preceeded to make the cylinder blocks from light metal; but, as a result, two different materials had to be used, namely light metal for the cylinder block and appropriate grey cast iron grades for the liners forming the cylinders. For this reason, attempts were made by means of structural measures to design a cylinder block which could also be made from grey cast iron while having a suitably high fatigue strength. A cylinder block of this type is described in WO 94/07017. When suitable grey cast iron grades are used, for example, compact graphite cast iron, it is possible to also produce a thin-walled cylinder block. A defined, straight-line force flow between a cylinder head and crankshaft bearing results from the arrangement of U-shaped reinforcing ribs on the outside of the water jacket in the region of the parting plane between respectively two adjoining cylinders and from an in-line association of the cylinder head screws with respect to the fastening screws of the bearing cap of the crankshaft bearing, which cap is attached from below. This allows a stability calculation with sufficient precision so that, in the dimensioning of the remaining, largely planar elements of the cylinder block which serve as a jacket, the wall thickness must practically be considered only with a view to a flawless casting ability. The previously known cylinder block, however, is designed such that the parts of the bearing shells forming the bearing duct are respectively cast integral in the parting plane between two cylinders via corresponding webs.
SUMMARY OF THE INVENTION
It is now the object of the invention to create a cylinder block that allows for still further weight reduction.
The invention accomplishes this object by a cylinder block for a multiple-cylinder internal combustion engine having a multiply seated crankshaft and having a water jacket surrounding the cylinders, with the outer wall of the water jacket being extended downward extending approximately into the parting plane of the crankshaft bearings and the circumferential free edge of the water jacket forming a contact face, and having a base frame which rests against this contact face and is connected with the same, on which base frame the crankshaft bearings are arranged whose detachable bearing caps are arranged on the side of the base frame facing the cylinders. This design offers the advantage that the forces that need to be absorbed between the cylinder head closing off the engine block towards the top and the crankshaft bearings are absorbed directly via the parts of the crankshaft bearings associated with the base frame, so that the associated bearing caps and their fastening screws must absorb correspondingly smaller forces and can therefore be dimensioned with correspondingly thinner walls. At the same time, the base frame offers a considerable stiffening of the free edge of the outer wall of the water jacket, which outer wall is extended downward; this results in a high fatigue strength of the block as a whole in spite of the small wall thickness. It is particularly advantageous if at least the cylinder block is made from vermicular cast iron (compacted graphite iron, advantageously compacted graphite iron 40) which, compared to other cast iron grades, has a higher loading capacity through tensile forces and a high internal damping for stresses due to vibrations, so that a "drumming" is eliminated in spite of the relatively thin walls. A further advantage of the design according to the invention is that the crankshaft bearings are completely mounted on the base frame and that the connection with the cylinder block is made only then.
An advantageous feature of the invention provides that the base frame is connected to the free edge of the outer wall of the water jacket by means of screws, with respectively two screws extending in the center plane of a crankshaft bearing.
REFERENCES:
patent: 4446827 (1984-05-01), Kubozuka
patent: 4520770 (1985-06-01), Ogawa
patent: 4651691 (1987-03-01), Ogawa
patent: 4922870 (1990-05-01), Pietsc et al.
patent: 5860404 (1999-01-01), Tanaka
Eisenwerk Bruehl GmbH
Hairston Brian
Spencer George H.
Voorhees Catherine M.
Wolfe Willis R.
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