Internal combustion engine

Details Internal combustion engine Internal combustion engine

2000-04-19

2001-03-06

McMahon, Marguerite (Department: 3747)

Internal-combustion engines

Particular piston and enclosing cylinder construction

Cylinder detail

C277S377000

Reexamination Certificate

active

06196179

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to an internal combustion engine with an engine block and a cylinder head, between which a cylinder head gasket is disposed, and a piston arranged in a cylinder having a cylinder surface with cylindrical ring disposed between the piston and the cylinder surface.
In modern internal combustion engines, particularly Diesel engines, it is necessary to provide sufficient play for the top land of the piston so that, at the operating temperature and the corresponding expansion of the aluminum piston, no contact occurs between the top land of the aluminum piston and the surrounding cylinder wall. The top land of a piston is the area between the uppermost piston ring, which is closest to the cylinderhead and the upper edge of the piston.
Especially with the use of synthetic oils for the lubrication of the internal combustion engine, there is the disadvantage that hard deposits are formed by combustion of the synthetic lubricant, which build up in the area of the top land and which finally contact the cylinder surface. During the reciprocating movement of the piston the hard deposits may then destroy the hone structure formed into the cylinder walls during manufacture. Then the cylinder surface loses the surface structure required for retaining a sufficiently thick lubricating oil film on the cylinder surface, which results in a high lubricating oil consumption and faster wear of the cylinder and the piston.
To avoid those effects, a cylindrical ring is being inserted in the area of the cylinder surface adjacent the cylinder head, that is, a recess is provided in the cylinder wall adjacent the cylinder head for receiving such a ring. The cylindrical ring projects from the cylinder wall surface and causes dislodging of the deposits in the area of the top land of the piston.
Such an arrangement is disclosed in principle in DAS 1 902 502. Furthermore, U.S. Pat. No. 5,553,585 describes a complex embodiment of such a ring arrangement.
It is however a disadvantage that such a ring requires space in radial direction which results in increased engine volume: For manufacturing reasons, the cylindrical ring has to have a certain wall thickness in order to be stable and to facilitate handling during assembly.
This is especially critical if the wall thickness behind the cylinder surface is already very small since for example a cylinder sleeve is inserted. In this case, high material tensions occur and a notch effect is generated in that area in which the cylinder sleeve has a very small wall thickness.
It is therefore the object of the present invention to provide an internal combustion engine with a cylindrical ring which provides for a gap between the top land of a piston and the respective cylinder wall surface. The cylindrical ring should require only minimal space in radial direction of the cylinder.
SUMMARY OF THE INVENTION
In an internal combustion engine with an engine block, a cylinder head mounted onto the engine block, a cylinder head gasket disposed between the engine block and the cylinder head, a piston disposed in a cylinder formed in the engine block and a cylindrical ring arranged in a recessed area between the piston and a cylinder area around the top land of the piston in the top dead center position of the piston, the cylindrical ring is formed as part of the cylinder head gasket.
Since the cylindrical ring according to the invention is an integral part of the cylinder head gasket, the wall thickness of the cylindrical ring can be substantially reduced as compared to all the known designs. The cylindrical ring which is formed with the base body of the cylinder head gasket has a minimal wall thickness, but is held in it proper shape by the base body of the cylinder head gasket.
Only the single-piece combination of the cylinder head gasket and the cylindrical ring in accordance with the invention has facilitated the manufacture of such a thin-walled ring. The base body of the cylinder head gasket mainly serves as a shape-maintaining aid and only secondarily as a support structure for the cylindrical ring. Consequently, the base body of the cylinder head gasket provides for a relatively high shape-rigidity of the cylindrical ring formed onto the cylinder head gasket.
In a particularly advantageous embodiment of the invention, the areas of the cylinder surfaces in a engine block directly adjacent the cylinder head are provided with recesses. The cylinder surface however may be part of a cylinder sleeve so that also the recesses are formed into the cylinder sleeves.
With the recesses formed into the areas of the cylinder sleeve or respectively, the engine block adjacent the cylinder head, the areas of the cylinder head gasket directly adjacent the cylindrical ring are not exposed to the pressure generated by the cylinder head.
This has the advantage that the cylinder head gasket seals around each cylinder only in the area of a stiffening corrugation formed into the gasket around each cylinder. In this way no uncontrolled forces are transmitted between the cylinder head and the engine block, or respectively, the cylinder sleeve. In addition, undetermined static clamping forces between the areas of the cylinder head surrounding the cylindrical ring and the engine block or, respectively, the cylinder sleeve are avoided. Also, the force transmission and the force flow from the cylinder head to the engine block can be well controlled.


REFERENCES:
patent: 3882842 (1975-05-01), Bailey et al.
patent: 4474147 (1984-10-01), Hoopes
patent: 5112066 (1992-05-01), Remmerfelt
patent: 5553585 (1996-09-01), Paro
patent: 5582144 (1996-12-01), Mizutani
patent: 5921558 (1999-07-01), Kozerski
patent: 5934682 (1999-08-01), Miszczak et al.
patent: 5970612 (1999-10-01), West
patent: 1 902 502 (1970-11-01), None
patent: 36 10 541 (1987-10-01), None
patent: 195 48 403 (1997-07-01), None

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