Patent Application
20100032909
The present disclosure relates to a cylinder head gasket assembly for an internal combustion engine.
Conventional internal combustion engines typically utilize a cylinder head and engine block. During operation internal combustion engines generate high temperatures; high pressured gases are generated in the cylinder bores of the engine block. The cylinder bores can be sealed using various sealing mechanisms to reduce the amount of gases that leak from the cylinder bore. If combustion gases leak from the cylinder bore, the gas may enter into one of the other orifices in the engine block. This may result in a loss of engine power and degrade the effectiveness of the cooling system. Therefore, it is desirable to effectively seal the combustion chamber. It is also desirable to have an engine gasket assembly with reduced material costs while providing adequate sealing.
In one exemplary embodiment, a cylinder head gasket assembly for an internal combustion engine includes: a sheet configured to fit between a cylinder head and engine block; an annular bead formed in the sheet configured to maintain sealing pressure during combustion; and a shim coupled to the bead in a manner to concentrate axial loading on the assembly during combustion.
In another exemplary embodiment, a cylinder head gasket assembly for an internal combustion engine includes: a sheet configured to fit between a cylinder head and an engine block; and a shim coupled to the sheet. The shim is biased with respect to the sheet in a manner to maintain sealing pressure and concentrate axial loading on the assembly during combustion.
In another exemplary embodiment, an internal combustion engine includes: an engine block having a plurality of cylinder bores; a cylinder head mounted with respect to the engine block; and a cylinder head gasket assembly fitted between the engine block and cylinder head. The gasket assembly includes: a sheet configured to fit between the engine block and cylinder head; and a shim coupled to the sheet configured to concentrate axial loading on the assembly during combustion. The shim is biased with respect to the sheet in a manner to maintain sealing pressure during engine combustion.
One advantage of the present invention is that the gasket assembly seals the cylinder bore better than prior art designs while using fewer parts and lower manufacturing costs. For example, the exemplary embodiments disclosed herein employ a single-sheet arrangement thereby requiring fewer parts than a multi-sheet assembly. The resulting reduction in gasket thickness minimizes chamber crevice volume as well thereby reducing CO2 emissions in the engine exhaust. Accordingly, the present invention also increases fuel efficiencies and overall engine performance.
Another advantage of the present invention is that it reduces extremities in the pressure distribution across the sheet at the cylinder bores. In this manner, it provides greater durability for the gasket assembly and overall engine.
The present invention provides a snug fit between the components of the gasket assembly. An annular bead with a semi-circular shaped profile is formed in the sheet, therefore better accommodating assembly, combustion and thermal loads than prior art arrangements.
Another advantage of the present invention is that it enables sealing without requiring complicated resin applications. In this manner, manufacturing and assembly of the gasket assembly is considerably simplified.
The invention will be explained in greater detail below by way of example with reference to the figures, in which the same references numbers are used in the figures for identical or essentially identical elements. The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. In the figures:
Referring to the drawings,
A gasket assembly 20 is placed between the engine block 40 and cylinder head 50. The gasket assembly 20, shown in
Shown in
The spring rate can be altered in various ways. For example, the shape of the profile of the bead can be altered to increase or decrease the stiffness of the bead 90. Different materials can be selected to accommodate a desired spring rate. The dimensions of the profile (or cross-section) of the bead can be configured to achieve a higher or lower spring rate. Alterations to the dimensions of the components of the gasket assembly can also be made to adjust the stiffness of the bead-shim coupling. For example the sheet thickness, bead width, bead height, profile shape, and shim height can be adjusted to alter the stiffness of the bead-shim coupling.
The sheet 80 is configured to fit between the engine block 40 and cylinder head 50 (as shown in
The sheet 80 includes secondary orifices e.g., 110 and 120. Orifices 110 are used for draining oil back from the cylinder head to the cylinder block. Orifices 120 are used to fit bolts from the cylinder head 50 through to the engine block 40 (as shown in
The illustrated embodiment of
The radius of curvature of the shim 220 and bead 240 in the sheet 230 can be larger or greater than that shown in
In one embodiment, the assemblies, e.g., 20 and 170, further include a coating of material that is sprayed along the perimeter of the combustion orifices 60. The coating material can also be selectively sprayed at other points on the sheet. In another embodiment, the coating is screen printed on the sheet. In one embodiment, the coating is composed of a compressible sealing material, such as rubber. In another embodiment, the coating is composed of a harder material such as a resin, fluoroplastic or plyamidcimido. The coating can be uniformly applied. In the illustrated embodiment, the coating material is of uniform thickness. The coating material can have a gradual thickness. For example, the coating material may be thicker at the end of the combustion opening but thinner at the bead and shim. The coating material can also be thicker on an outer diameter of the shim to support the seal without adding height to the gasket assembly.
Sheets 80, 230, 320 can be manufactured using a number of techniques. For example, in one embodiment, the sheet is stamped. In another embodiment, the sheet is laser cut and the bead is formed at the combustion opening. The bead can be formed in the sheet using any number of manufacturing techniques, such as stamping, crimping, etc. The shim can be attached to the sheet via laser welding for example. The sheet can be formed of a variety of materials such as metal alloys. In one embodiment, the sheet is formed of a metallic composite such as stainless steel (e.g., SS 301). Other Chromium-Nickel steels capable of attaining high strength with moderate cold working can be employed. In one embodiment, the sheet is formed of a 0.25 mm thick sheet of SS 301. The metallic components of the gasket assembly are laminated. The shim is composed of a metallic material. In one embodiment, the shim is composed of a 0.100 mm 301 SS. The thickness of each component is variable and not limited to the dimensions disclosed herein.
While the shims 100, 220 and 310 shown in the illustrated embodiments are shown on top of the bead, the shim may be constructed to define a space between the shim and the bead. For example, in one embodiment the shim and bead include a gap or spacing between them. The shim can also be placed beneath (or underneath) the bead in an alternative embodiment. An additional embodiment includes more than one shim to act as a support member to the gasket assembly. The shim and/or sheet can also be formed so that multiple layers of metal are provided at the combustion orifice without requiring a substantial amount of additional material. In one embodiment, multiple shims are coaxially mounted with respect to the axial bead. The shims and bead have substantially similar diameters so that the shims can be stacked on top of or underneath the bead. In this manner, additional support is provided to the bead without requiring multiple sheets. The shim can be formed using a number of manufacturing techniques such as e.g., laser cutting, stamping, etc. The shim can be attached to the sheet via press fitting, stamping, welding, gluing, etc.
The invention has been described with reference to certain aspects. These aspects and features illustrated in the drawings can be employed alone or in combination. Modifications and alterations will occur to others upon a reading and understanding of this specification. Although the described aspects discuss steel as one material of construction, it is understood that other materials can be used for selected components if so desired. It is understood that mere reversal of components that achieve substantially the same function and result are contemplated, e.g., biasing the shim with respect to the sheet of the gasket assembly can be achieved via various configurations without departing from the present invention. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
While several examples for carrying out the invention have been described, those familiar with the art to which this invention relates will recognize alternative designs and embodiments for practicing the invention. Thus, the above-described embodiments are intended to be illustrative of the invention, which may be modified within the scope of the following claims.
