Internal-combustion engines – Cooling – With jacketed head and/or cylinder
Reexamination Certificate
1999-10-12
2001-07-24
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Cooling
With jacketed head and/or cylinder
C123S041840
Reexamination Certificate
active
06263840
ABSTRACT:
The present invention concerns an engine block of a metal material for a multicylinder internal combustion engine, with a housing, in which cylinder boreholes are provided, whereby the outer surfaces of the side walls of the cylinder boreholes are distanced from the walls of the housing, so that cooling channels arranged between the walls and the cylinder boreholes result. The present invention also concerns a cylinder bushing for such an engine block as well as a method for the production of such an engine block.
Such engine blocks are known. They are cast in grey castings of iron or light metal, depending on the material used. Then loose cylinder bushings can be utilized in the cylinder boreholes, insofar as these are not already cast with them; their inner walls represent the sliding surfaces for the pistons. The upper side of the side wall of the cylinder borehole serves as the support surface for the cylinder head gasket.
Prefinished cast engines blocks can be post-machined (“tuned up”) to increase the engine performance. For this purpose, the cylinder boreholes are re-bored, i.e., their diameter is enlarged. A corresponding enlargement of the [piston] stroke space results from this. Of course, the thickness of the side walls is reduced. It is a problem that the surface of the upper side of the cylinder boreholes and thus the support surface for the cylinder head gaskets is simultaneously reduced. The danger arises that the cylinder head gaskets no longer sit perfectly and no longer can guarantee a sufficient seal after the post-machining.
The object of the present invention consists of producing an engine block or a cylinder bushing of the type named above, which also has a sufficient support surface for the cylinder head gasket after enlarging the stroke space.
The solution consists of the fact that the cylinder boreholes are shortened, so that the height of the shortened cylinder boreholes is smaller than the height of the unshortened cylinder boreholes.
In such an engine block, according to the invention, cylinder bushings can be utilized, which have a sleeve and a collar, the outer diameter of which is larger than the outer diameter of the sleeve. The cylinder bushing is inserted into the shortened cylinder borehole, whereby the underside of the collar sits on the upper side of the side wall. The surface of the collar thus represents the support surface for the cylinder head gasket. Thus a sufficiently large support surface is available for the cylinder head gasket, so that it has a solid support and a perfect seal is assured.
Advantageous further embodiments result from the subclaims. The magnitude of difference between the outer diameter of the collar and sleeve of a cylinder bushing can be larger or the same, but preferably larger, than the magnitude of the wall thickness of the side wall of the assigned cylinder borehole. Thus a maximum support surface is available for the cylinder head gasket.
The engine block according to the invention is produced by metal-cutting [machining], for example, by milling the side walls of the cylinder boreholes of a finished engine block, so that they are shortened. This method is particularly offered for post-machining within the scope of engine tuning, in which, for example, the wall thickness of the side walls of the cylinder boreholes is also reduced. Of course, the engine block according to the invention can also be cast directly in an appropriate shape.
REFERENCES:
patent: 2635592 (1953-04-01), Hollis
patent: 4616600 (1986-10-01), Hirano
patent: 4846116 (1989-07-01), Sakurahara et al.
Harris Katrina B.
Kriegsman & Kriegsman
Wolfe Willis R.
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