Cylinder-head gasket for internal-combustion engine

A cylinder-head gasket comprises a metal core plate having two faces and formed with a plurality of cylinder holes, an annular groove of a predetermined depth around each cylinder hole on one of the plate faces, a plurality of stud holes, and a plurality of lubricant/coolant holes. This plate is normally made of stainless steel, a specialty steel, or a steel with a special surface treatment or coating. A resilient seal normally made of a fluorocarbon or silicone is provided on each of the core-plate faces around the lubricant/coolant holes. A cylinder plate of a thickness greater than the groove depth forms respective cylinder rings of the plate thickness sitting in the grooves around each of the cylinder holes. This cylinder plate is normally of a stainless or specialty steel also.

FIELD OF THE INVENTION 
The present invention relates to cylinder-head gasket. More particularly 
this invention concerns such a gasket used on a high-compression internal 
combustion engine, normally a diesel. 
BACKGROUND OF THE INVENTION 
A standard cylinder-head gasket is compressed between the cylinder head and 
the block of an engine and is formed with through going holes for the 
cylinders, the head-mounting studs, and the coolant and lubricant 
circuits. This gasket is normally formed as a perforated plate of steel 
covered with a durable and heat-resistant material such as asbestos, 
although in some cases use is made of glass fibers, or a synthetic resin 
such as Kevlar. For a given engine there are normally three thicknesses 
available for installation normally when the engine is rebuilt. 
In today's engines it is standard, particularly in diesels, to have a very 
high compression ratio, typically around 20:1 (ratio of maximum to minimum 
cylinder volume) as compared to the older low-compression engines where 
the ratio is 9:1 to 10:1. As a result of this high compression it is 
extremely important that the cylinder-head gasket be dimensioned to very 
close tolerances. This is particularly the case for a rebuilt engine. 
Not only is asbestos a particularly difficult and dangerous material to 
work with, but the precise requirements of such a gasket, in several 
different thicknesses, make production complex and expensive. 
OBJECTS OF THE INVENTION 
It is therefore an object of the present invention to provide an improved 
cylinder-head gasket. 
Another object is the provision of such an improved cylinder-head gasket 
which overcomes the above-given disadvantages, that is which can be 
produced at low cost to high tolerances. 
SUMMARY OF THE INVENTION 
A cylinder-head gasket according to the invention comprises a metal core 
plate having two faces and formed with a plurality of cylinder holes, an 
annular groove of a predetermined depth around each cylinder hole on one 
of the plate faces, a plurality of stud holes, and a plurality of 
lubricant/coolant holes. This plate is normally made of stainless steel, a 
specialty steel, or a steel with a special surface treatment or coating. A 
resilient seal normally made of a fluorocarbon or silicone is provided on 
each of the core-plate faces around the lubricant/coolant holes. A 
cylinder plate of a thickness greater than the groove depth forms 
respective cylinder rings of the plate thickness sitting in the grooves 
around each of the cylinder holes. This cylinder plate therefore stands up 
past the core plate and itself is normally of a stainless or specialty 
steel also. 
Thus with this system the cylinder-ring plate and the core plate are 
separate elements, so that the same cylinder plate can be used with core 
plates of different thicknesses to make gaskets of different thicknesses. 
In fact according to the invention the seals are molded on the core plate 
and this same mold is used with core plates of different thicknesses to 
form gaskets of different thicknesses. It is therefore possible to produce 
the desired three different thicknesses of gaskets by using the same 
cylinder plates and seals, but with core plates, which typically are 
stamped at relatively low cost, of different thicknesses. 
According to another feature of this invention solder spots or adhesive 
spots secure the cylinder and core plates together. It is also possible 
for the cylinder plate to be force-fitted into the grooves.

SPECIFIC DESCRIPTION 
As seen in the drawing a cylinder-head gasket according to the invention 
comprises a sheet-steel plate 2 formed with four relatively large in-line 
circular cylinder holes 3, small holes 4 for the head-mounting studs, and 
holes 5 for the passage of lubricating oil and coolant. A resilient seal 6 
runs annularly around the outer periphery of the gasket on each face and 
prevents the liquid lubricants and coolants from leaking out. 
As best seen in FIG. 3 the plate is formed around the edge of each hole 3 
with a recess 7 and these recesses 7 run together between the holes 3 so 
they can receive a plate 8 forming four cylinder-seal rings 9. This plate 
8 is made of stainless or specialty steel and also is formed adjacent each 
cylinder hole 3 with a tab 10 for covering a precombustion chamber. FIG. 3 
shows clearly that the plate 8 has a thickness T which is roughly twice 
the thickness t of the plate 2 and also substantially greater than the 
depth d of the grooves or recesses 7. In addition the plate 8 is formed 
with rigidifying ridges 12 and grooves 13 on its opposite faces, the 
latter lying against the plate 2. 
In practice regardless of the desired thickness for the gasket, the same 
plate 8 is used and the different thicknesses T are obtained by using 
plates 2 of different thicknesses t. The seals 6 are molded directly onto 
the faces of the plate 9 by means of a mold which is used with plates 2 of 
different thicknesses to produce gaskets of different thicknesses. The 
plates 2 and 8 can be held together at 14 by small solder spots or welds, 
or even by adhesives. It is also possible to force fit the rings 9 into 
the grooves 7.