Gaskets for cylinder heads

A gasket for sealing the joint between the cylinder block and the cylinder head of a wet liner internal combustion engine comprising a pair of outer metal plates (1), a metal spacer plate (2) between the two outer plates and comprised of an essential soft metal layer and hard metal surface layers there being fitted around each cylinder bore opening a metal washer (7) formed on each axial face with circumferential serrations (7a) of V-shaped profile. The thickness of the washer (7) measured over the peaks of the corrugations (7a) is somewhat greater than that of the spacer plate (2) whereas the thickness measured between the troughs of the serrations (7a) is significantly less than that of the spacer plate (2). According to the invention the outer metal plates (1) and central metal plates (2) have their edges spaced away from the individual cylinder bore openings whereas the washer (7) has its radially inner portion formed with the serrations (7a) which extend to the edge of the bore openings, whereas only its radially outer part is accommodated between the two outer metal plates (1).

In my co-pending British Pat. No. 2,064,677 there is disclosed an improved 
gasket for sealing the joint between the cylinder block and the cylinder 
head of a wet liner internal combustion engine. This gasket comprises a 
pair of outer plates having outwardly directed corrugations formed therein 
away from cylinder bore openings and a composite metal spacer plate 
disposed between the two outer plates. The metal spacer plate comprises a 
central soft metal layer and hard metal surface layers and around each 
cylinder bore opening and between the outer metal plates is a metal washer 
formed on each axial face with circumferential serrations of V-shaped 
profile. The thickness of the washer measured over the peaks of the 
corrugations is somewhat greater than that of the spacer plate whereas the 
thickness measured between the troughs of the serrations is significantly 
less than that of the spacer plate. 
As originally devised, the two outer plates of the gasket together with the 
contained serrated washer extended up to the edge of each cylinder bore 
but in some installation instances due to lack of space and operating 
conditions this was not practical. 
After research to discover an alternative but equally advantageous gasket 
there has now been devised according to the invention a gasket of the kind 
defined above which is characterised in that the outer and central metal 
plates have their edges spaced away from the individual cylinder bore 
openings whereas the serrated washer extends to the edge of those openings 
and has only its radially outer part accommodated between the two outer 
metal plates.

The gasket which is shown in the drawings and hereinafter described is 
intended to seal the joints between the cylinder block and the cylinder 
head of a bank of four cylinders of a V-8 compression ignition wet liner 
engine. The main part of this gasket is constructed in substantial 
accordance with the disclosure of my co-pending British Patent Application 
No. 7,940,625. 
As shown most clearly in FIGS. 2, 3 and 4 the gasket comprises two outer 
cold rolled mild steel bright annealed BS2920 tin steel plates 1, each of 
0.015 inches thickness and an interposed central composite spacer plate 2 
which is 0.025 inches in thickness. This plate 2 is of cold rolled mild 
steel pinched nipped grade CS4 RCS (SP4BR) which has been zinc plated. It 
has however also been subjected before plating to a skin rolling operation 
which has the effect of forming a hard metal layer on each of its 
surfaces. Apart from this, the outer plates 1 are formed with corrugated 
configurations of two different forms. The paths of these corrugations on 
the gasket are illustrated in chain-dashed lines in FIG. 1, the chain 
lines being drawn at the peaks or locus points of the lines of 
corrugations. 
Referring to FIG. 1 in conjunction with FIG. 2, one form of corrugation 
which runs along one side margin of the gasket is of single V-shaped 
profile. The single wave has an overall width of 1/16th inch and the 
corrugations are proud of the remainder of the outer plates by 0.025 
inches. 
The other form of corrugation is shown in FIG. 3 in conjunction with FIG. 1 
and is of double V-shaped profile. This double V-shaped profile has the 
characteristic defined in my co-pending British Patent Application 4350/78 
in that the distance d between a plane which contains the apices of the 
two waves and a plane parallel thereto which contains the base of the 
trough between the two waves is significantly less than the distance 
between the first plane and the base plane of the sheet. In the present 
instance the overall width of the two waves is 1/8 inch, the distance 
between wave peaks is 1/16 inch and the distance d is 0.013 inches. 
In order to understand how the gasket is equipped in order to ensure 
satisfactory gas tight sealing in the region of the four cylinder bores 
reference should now be made to FIG. 1 in conjunction with FIG. 4. 
Around each cylinder bore opening 4 in the gasket for a radial distance r 
sufficient to bridge a wet liner and the adjacent margin of the cylinder 
block there is fitted a washer 7. The radially outer part of this washer 
is clamped between the outer plates 2 of the gasket and the radially 
inward part of the washer 7 has annular serrations 7a on opposite sides. 
These serrations are of equal pitch at angular dispositions of 120.degree. 
to one another and the total radial extent of the serrations in this 
instance is 0.266 inches. The maximum thickness of the washer 7, measured 
over the peaks of the serrations 7a is 0.062 inches and the intervening 
distance between the troughs of the serrations is 0.028 inches. The 
maximum thickness of the washer 7 thus somewhat exceeds the thickness of 
the spacer plate 2, thus ensuring high unit loading. The washer 7 may be 
made of zinc plated steel or, as in the present instance, from stainless 
steel depending upon the operating temperature of the engine in which the 
gasket is to be installed.