Metal laminate type cylinder head gasket with heat preventing portion

#The present invention relates to a metal laminate type cylinder head gasket having a portion for preventing or reducing heat from a cylinder bore of the engine. Also, deformation of a cylinder block around the cylinder bore is reduced.

#An automobile engine has been developed to provide high power and light weight. For this purpose, a cylinder head is made of an aluminum alloy, and in some cases, a cylinder block is also made of an aluminum alloy. In case the cylinder block is made of an aluminum alloy, rigidity of the aluminum alloy is not strong. Thus, if high sealing pressure is applied around the cylinder bore by a gasket, the cylinder block may deform.

#Further, when the engine is operated, combustion temperature in the cylinder bore become very high. Thus, the gasket situated between the cylinder head and the cylinder block must withstand the high temperature. Also, a seal coating is effective for sealing between the plates of the gasket or between the gasket and the cylinder block or cylinder head. However, in case temperature in the cylinder bore is very high, creep relaxation of the seal coating may occur due to high temperature. Thus, the seal coating is not used for a gasket installed in a high temperature engine.

#FIG. 1 is a plan view of a part of a first embodiment of a cylinder head gasket of the invention;

#FIG. 2 is an enlarged section view taken along a line 2--2 in FIG. 1;

#FIG. 3 is a section view, similar to FIG. 2, to show a second embodiment of a cylinder head gasket of the invention; and

#Referring to FIGS. 1 and 2, a first embodiment A of a cylinder head gasket of the invention is shown. The gasket A includes a plurality of cylinder bores Hc, water holes Hw, oil holes Ho and bolt holes Hb, as in the conventional gasket.

#The present invention is directed to the sealing structure around the cylinder bore Hc. Therefore, sealing mechanisms for other holes are not explained. Any sealing mechanisms may be used for other holes.

#As shown in FIG. 2, the gasket A is formed of a first or an upper plate A10, and a second or lower plate A11, which extend substantially throughout the entire area of the engine (not shown) to be sealed. The first plate A10 includes a heat preventing portion A10a situated around the cylinder bore Hc, a main sealing portion A10b situated around the heat preventing portion A10a, and a base portion A10c situated outside the main sealing portion A10b.