Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal between parts of internal combustion engine
Reexamination Certificate
2000-10-18
2002-04-30
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal between parts of internal combustion engine
C277S595000
Reexamination Certificate
active
06378876
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metal gasket assembly for a cylinder head, which is interposed between a cylinder block and a cylinder head of an internal combustion engine.
2. Related Art
For example, as disclosed in Japanese Utility Model Laid-Open No. H4-71865, a metal gasket assembly for a cylinder head has been conventionally known, having a structure shown in FIG.
4
. This conventional metal gasket assembly
1
comprises a metal main plate
2
and a metal auxiliary plate
3
, and a metal surface pressure adjusting plate
4
. The main plate
2
is formed therein with main plate cylinder openings
2
a
in positions corresponding to cylinder bores of a cylinder block of an internal combustion engine, main plate annular beads
2
b
formed around the main plate cylinder openings
2
a,
being projected downward, and having a cross-sectional shape of ‘V’ (the so-called full bead shape), and a main plate outer peripheral bead
2
c
formed so as to entirely surround the main plate annular beads
2
b
and a plurality of not shown coolant holes formed in the peripheral parts of the main plate annular beads
2
b,
and having a cross-sectional shape of slope (the so-called half bead shape). The auxiliary plate
3
comprises auxiliary plate cylinder openings
3
a
formed at positions corresponding to the main plate cylinder openings
2
a,
fold-over parts
3
b
which are folded around the peripheral edges of the auxiliary plate cylinder openings
3
a
in the auxiliary plate
3
in a direction toward the main plate
2
, and which have a width with which the fold-over parts
3
b
are vertically lapped with the entire ‘V’ cross-sectional shape of the main plate annular beads
2
b
on the main plate
2
, and a plurality of not shown auxiliary plate coolant holes formed corresponding to the above-mentioned main plate coolant holes in the main plate
2
. The auxiliary plate
3
is entirely formed into a flat shape having no beads so as to be lapped below the above-mentioned main plate
2
. Further, the above-mentioned surface pressure adjusting plate
4
has a planer shape corresponding to that of the auxiliary plate
3
, except the above-mentioned fold-over parts
3
b,
and is interposed between the auxiliary plate
3
and the main plate
2
, the thickness of the surface pressure adjusting plate
4
being thinner than that of the auxiliary plate
3
in the part which excludes that of the fold-over parts
3
b.
The above-mentioned conventional cylinder head metal gasket assembly
1
is interposed between a cylinder block
5
and a cylinder head
6
in an internal combustion engine, as shown in
FIG. 4
, and is fastened so that the main plate annular beads
2
b
formed around the main plate cylinder openings
2
a
corresponding to the cylinder bores
5
a
in the cylinder block
5
can prevent combustion gas in combustion chambers defined by the cylinder bores
5
a
in the cylinder block
5
, recessed parts
6
a
in the cylinder head
6
opposed to the cylinder bores and the top parts of not shown pistons in the cylinder bores
5
a,
from blowing to the outside, and the main plate outer peripheral bead
2
c
entirely surrounding the above-mentioned plurality of main plate coolant holes corresponding to not shown coolant passages which are formed in the cylinder block
5
and the cylinder head
6
and mutually communicated, can prevent coolant from leaking.
Further, in the cylinder head metal gasket assembly
1
, the auxiliary plate
3
is formed with the fold-over parts
3
b
at positions corresponding to the main plate annular beads
2
b
on the main plate
2
so as to increase the thickness of the auxiliary plate
3
, and meanwhile, the surface pressure adjusting plate
4
which is thinner than the auxiliary plate
3
is lapped with the auxiliary plate
3
, except the positions corresponding to the main plate annular beads
2
b
on the main plate
2
, so as to adjust the distribution of the surface pressures between the main plate annular beads
2
b
and parts other than the beads
2
b
in order to enhance the sealing function.
In the meantime, these years, engines made of aluminum alloy have been prosperously used in order to save fuel consumption due to reduction in the weight of a vehicle, and accordingly, cylinder blocks made of aluminum alloy have been frequently used. Further, in the case of an cylinder block made of aluminum alloy, as shown in
FIG. 4
, there haven been frequency used the following measures, that is, sleeve fitting holes
5
b
having a size which is much greater than that of the inherent cylinder bores are formed in the cylinder block
5
at positions where the cylinder bores are to be formed, and cast iron sleeves
7
having high lubricity are press-fitted in the sleeve fitting holes
5
b
so as to define the cylinder bores
5
a
in the cast iron sleeves
7
in order to aim at preventing abrasion of the inner wall surfaces of the cylinders and seizure of the pistons. These sleeves
7
are pressed by reaction force when the metal gasket assembly
1
is fastened between the cylinder block
5
and the cylinder head
6
, and accordingly, tends to be slightly depressed from the upper end surface of the cylinder bock
5
, as indicated by a degree t of depression shown in the figure.
However, in the above-mentioned metal gasket assembly
1
, if the width of the fold-over parts
3
b
in the auxiliary plate
3
is greater than the thickness of the cast iron sleeves
7
, the fold-over parts
3
b
of the auxiliary plate
3
extend up to positions above the upper end surface of the cylinder bock
5
, exceeding the cast iron sleeves
7
, and accordingly, if the cast iron sleeves
7
are depressed as mentioned above so as to define a difference in height between the upper end surface of the cylinder block
5
and the upper end faces of the cast iron sleeves
7
, the fold-over parts
3
b
cannot cope with the difference in height, resulting in that the fold-over parts
3
b
of the auxiliary plate
3
are caught between the upper end surface of thee cylinder block
5
and the lower end surface of the cylinder head
6
. Thus, the fold-over parts
3
b
hinders the metal gasket assembly
1
from being sufficiently fastened, and accordingly, there has been raised such a problem that the main plate annular beads
2
b
of the main plate
2
cannot be sufficiently fastened between the upper surface of the cast iron sleeves
7
and the lower end surface of the cylinder head
6
so that no high sealing function can be obtained.
Further, in the above-mentioned metal gasket assembly
1
, the above-mentioned fold-over parts
3
b
faces toward not to the cast iron sleeves
7
but the main plate
2
, and the flat part of the auxiliary plate
3
faces toward the cylinder block
5
and the upper end surfaces of the cast iron sleeves
7
, and accordingly, even though the width of the fold-over parts
3
b
is decreased so that the fold-over parts
3
b
are prevented from overlapping the upper end surface of the cylinder block
5
, the main plate annular beads
2
b
of the main plate
2
cannot be fastened on the upper surfaces of the cast iron sleeves
7
unless the flat part of the auxiliary plate
3
is deformed into a half bead-like shape. Incidentally, the surface pressure adjusting plate
4
is also caught between the upper surface of the cylinder block
5
and the lower surface of the cylinder head
6
so as to hinder the main plate annular beads
2
b
from being sufficiently fastened on the upper end surfaces of the cast iron sleeves
7
. Accordingly, there has been raised such a problem that the main plate annular beads
2
b
cannot be sufficiently fastened so that no high sealing function cannot be obtained.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a metal gasket assembly which can advantageously solve the above-mentioned problems, and accordingly, the metal gasket assembly according to the present invention, comprises a metal main plate, and a metal auxiliary plate mutually lapped with the main plat
Knight Anthony
Nippon Leakless Industry Co. Ltd.
Pickard Alison K.
Young & Thompson
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