1. Field of the Invention
The subject invention relates generally to multi-layered gasket assemblies for use in internal combustion engines.
2. Related Art
Multi-layered gasket assemblies are traditionally used to form a seal between two mating components of a mechanical system or device, such as an internal combustion engine, to prevent leakage of combustion gases, cooling water, lubricating oil, or the like. Common applications involve placing a multi-layered gasket assembly between an engine block and a cylinder head and between a cylinder head and an exhaust manifold. Cylinder head gaskets typically extend around the cylinder bores of an engine to seal high-pressure combustion gases within the cylinder bores as well as to seal oil and coolant passages. Exhaust manifold gaskets typically extend around the exhaust ports of an engine to seal high temperature exhaust gases flowing into the exhaust system. Once installed, the multi-layered gasket assembly bears the load from a bolted connection of the engine components and relies upon this load to provide an adequate seal therebetween.
Many of today's internal combustion engines utilize sleeves, also known as cylinder liners, which are inserted into the cylinder bores of the engine block. The sleeves are generally cylindrical in shape and are disposed in the cylinder bore between the engine block and piston. Often, the sleeves are made of a different metal or alloy than that used for the engine block. For example, an internal combustion engine may have an engine block that is made of aluminum and sleeves made of steel or cast iron. These metals have different rates of thermal expansion. Accordingly, a condition may occur during the operation of the engine where the sleeve undergoes thermal loading and expands and contracts axially with respect to the cylinder bore. As the sleeve is subject to high temperature, the sleeve may expand axially and deform the gasket assembly thereby permanently changing the shape. Such a permanent deformation of the gasket assembly is undesired because of the resiliency of the gasket assembly is lost affecting the sealing capability of the gasket. As the sleeve cools, the sleeve may contract axially and leave a gap between the sleeve and the gasket assembly causing a small combustion gas leak.
Prior art multi-layered gasket assemblies typically include gasket layers having inboard edges circumscribing the apertures. The gasket layers also have outboard regions radially spaced from the apertures. In cylinder head gasket applications, the apertures correspond with cylinder bores of the internal combustion engine. In exhaust manifold gasket applications, the apertures typically correspond with the exhaust ports of the internal combustion engine. Typically, several gasket layers are stacked in relation to one another. The gasket layers also typically include sealing beads disposed between the inboard edge and the outboard region to increase the sealing capability. The sealing beads extend annularly about each aperture. The sealing beads may include a primary sealing bead extending circumferentially about the aperture. The sealing beads may further include a secondary sealing bead adjacent the primary sealing bead.
Some of the prior art multi-layered gaskets include a stopper layer disposed between the gasket layers, such as disclosed in U.S. Pat. No. 6,722,662 to Heilig et al. and U.S. Pat. No. 6,827,352 to Ueta et al. Despite the existence and positioning of the stopper layer, small combustion gas leaks can develop between the stopper layer and the gasket layer, particularly due to the expansion and contraction of the cylinder bore sleeve during use of the engine.
In accordance with an embodiment of the invention, the gasket assembly includes a gasket layer having inboard edges circumscribing the cylinder bores and outboard regions radially spaced from the apertures. Primary sealing beads are disposed between the inboard edge and the outboard region. Secondary sealing beads are disposed in the gasket layer between the primary sealing beads and the inboard edges. Stopper layers extend radially from the outboard region to the inboard edge of the gasket layer. The stopper layers entirely overlap the primary sealing beads and the secondary sealing beads. Intermediate layers can be included also.
The inventive gasket assembly is more resilient and can accommodate the expansion and contraction of the cylinder sleeves as they expand and contract during use. With the stopper layer overlapping both beads, the compressive force exerted on the gasket assemblies by the expanding sleeves is distributed over the entire radial length of both sealing beads. This prevents the sleeves from deforming the sealing beads and from creating possible gas leaks.
These and other advantages and features of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.
Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a multi-layer steel gasket assembly 20 is illustrated for use to provide sealing between an engine block and a cylinder head of an internal combustion engine. Referring to
It is to be understood that although the present invention has particular use for sealing apertures in cylinder blocks, the invention can also be used to seal other apertures in other areas, such as exhaust ports, cooling channels, threaded bores for receiving fasteners, and other apertures and voids in the cylinder head or engine block. As shown in FIGS. 3 and 4A-4B, the engine block 22 may further include a deck surface 36 adjacent the cylinder head 24 and at least one sleeve 38 disposed in the cylinder forming an inner cylinder wall 40.
Also, it is preferred that the inboard edges 30 of the gasket layers 26, 28 be radially aligned with the cylinder wall. If the engine has sleeve members 38 positioned in the cylinder bores, as shown in
The cylinder sleeve member 38 is generally cylindrical in shape and is disposed in the cylinder bore between the engine block 22 and piston 42. The sleeve 38 may be made of a different metal or alloy than that used for the engine block 22. For example, the engine block 22 may be made of aluminum and sleeves 38 may be made of steel or cast iron. These metals have different rates of thermal expansion. Accordingly, a condition may occur during the operation of the engine where the sleeve 38 undergoes thermal loading and expands and contracts axially with respect to the cylinder bore. Since the sleeve 38 is constrained in the cylinder bore, the principal expansion and contraction is axial travel of an exposed end 44 of the sleeve 38 adjacent the deck surface 36 of the cylinder block. As the sleeve 38 is subjected to high temperatures during use of the engine, the sleeve member 38 may expand axially such that the exposed end 44 protrudes from the deck surface 36 as shown in
Although the present invention has particular use where the cylinder liner is pressed into place in a cylinder bore, the invention also has benefits when used with engines with cast-over liners or with engines without liners.
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The primary sealing beads 56, 58 are spaced from the inboard edge 30 of the gasket layer 26, 28 and typically completely enclose and surround the aperture. The primary sealing beads may have concave shapes relative to the intermediate layers 54 as shown in
The gasket assemblies 20 also include at least one secondary sealing bead 62 disposed between the primary sealing bead 56, 58 and the inboard edge 30 of the gasket layers. Accordingly, the secondary sealing beads 62 are positioned radially inward of the primary sealing bead 56, 58 and preferably extend circumferentially entirely around and enclose the aperture. In an alternate embodiment, the secondary sealing bead 62 may have a limited circumferential extent and extend along only the axially aligned bridge portions 50 of the gasket assembly. Referring to
The secondary sealing beads 62 extends radially along a second radial length 64 corresponding to a maximum radial length as measured between the two most radially distant points of the structure forming the secondary sealing bead 62. The secondary sealing bead 62 may take a variety of different shapes and may extend in several directions and can be described generally as having an “S-type” shape and curvature. Referring to
In general, the “S-type” curve of the secondary either bends toward or away from the convex or concave curved structure of the primary sealing bead. The “S-type curve” starts with a first end in alignment with the planar structure of the gasket layer, curves up or down in a first portion away from the plane of the gasket layer and then terminates with a second end back in alignment with the plane of the gasket layer. This shape is shown in
Taking
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As indicated above, it is preferred that the inner edges 30 of the gasket layers 26, 28 be radially aligned with the cylinder wall. Similarly, it is preferred that the inner edges of the intermediate layers and stopper layers 66 also be aligned with the walls or edges of the cylinder bores, or with the inner walls or edges of sleeve members if present. This preferred embodiment is shown in
The material for the gasket layers, intermediate layers and stopper layers can be what are typically used for components in cylinder head and exhaust manifold gaskets known today. Preferably, for the present invention, the gasket layers and stopper layers are made of stainless steel (for example, SS301 or SS201). It is possible for the stopper layer to be made of SS304 or cold roll steel. The intermediate layers are preferably made of cold roll steel, but also could be made of black plate, tin coated steel, or zinc plated steel.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the appended claims. These antecedent recitations should be interpreted to cover any combination in which the inventive novelty exercises its utility. In addition, the reference numerals in the claims are merely for convenience and are not to be read in any way as limiting.