Patent Application
20130038027
The subject matter disclosed in this application relates to gaskets and gasket assemblies. More specifically, but not by way of limitation, the present application relates gasket assemblies for use with an exhaust manifold in internal combustion engines.
Internal combustion engines typically include a cylinder head disposed above cylinders on top of a cylinder block. The cylinder head forms the combustion chamber by enclosing the cylinder. The cylinder head may include ports for the fuel/air, exhaust gases and coolant. The joint between the cylinder head and the cylinder is typically sealed by a gasket (head gasket). The gasket fills the space at the joint between the two mating surfaces to prevent leakage. In some engines a gasket is used to seal the interface between the cylinder head and the exhaust manifold, and in applications where the exhaust manifold is water cooled, the same gasket is used to seal a coolant passage and an exhaust port.
Gaskets that seal a coolant passage and an exhaust port operate in a severe environment. There may be a steep temperature gradient between the exhaust port and the coolant passage. For example, an exhaust port may have a temperature of approximately 1300° F. (704° C.) while the coolant passage may have a temperature of approximately 180° F. (82° C.). Additionally, there is a problem with the coolant chemically reacting with the materials used in the gasket components. This severe environment may cause failure of the gasket components. Significant damage to the engine may occur if the gasket fails. The damage may result from exhaust gases being injected into the cooling system, or coolant leaking into the cylinders or exhaust.
Furthermore, there may be significant space constraints when the gasket is changed on an engine. Typically, the cylinder head and exhaust manifold remain rigidly fixed to the engine when the gasket flange mounting bolts are removed so there is very little space available to remove and replace gaskets.
There are a number of known gasket configurations for improving the performance of the gaskets. For example, copper o-rings may be provided around the coolant passage to prevent leakage. However, the copper o-rings do not expand and contract sufficiently with temperature changes. Also, because of the aforementioned space constraint, field technicians occasionally strike the o-ring with a hammer in order to fit the gasket into the application. Both of these conditions may cause gasket failure resulting in coolant leaks.
Another known gasket configuration includes an EPDM material (ethylene propylene diene monomer) grommet that is glued to the inner diameter of a copper o-ring. The grommet may be exposed to temperatures as high as approximately 313° F. (156° C.). In many cases, the EPDM material cannot withstand the high application temperature to which it is exposed. Also, because the grommet ID is smaller than the coolant passage the grommet may be damaged by the flow of coolant in the coolant passage. This known design may adequately seal the exhaust port but does not effectively seal the coolant passage.
Thus, there is a need for a gasket assembly that effectively seals the exhaust port and the coolant passage and that is not susceptible to failure resulting from the extreme temperature gradients and exposure to the coolant.
In some embodiments a gasket assembly is provided including a gasket element having at least one opening through which the coolant flows; and at least one coolant seal disposed in the opening. The coolant seal includes a ring and a protective cover that reduces the surface area of the ring that is in direct contact with the coolant.
In some embodiments the ring in the coolant seal may be a grommet of elastomeric material.
In some embodiments the protective cover in the coolant seal may be a metal ferrule disposed along the internal surface of the grommet.
In other embodiments, the gasket element in the gasket assembly includes an inner core and a plate of uniform thickness encasing the inner core.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Referring now to the figures, where the various numbers represent like parts throughout the several views,
As illustrated in
In one embodiment, the gasket element 13 is a three layer element with core 23 made of vermiculite and ceramic fiber bonded with nitrile rubber binder (NBR) sandwiched between a metal upper plate 25 and a metal lower plate 27. The metal upper plate 25 and the metal lower plate 27 may be of similar thickness, generally about 0.010 inches (0.254 mm). One embodiment of the metal plates comprises mild steel metal plates. In another embodiment, the core 23 may be an inorganic mineral fiber-based core such as those used with a mechanically clad composite (MCC) gasket. The gasket element 13 performs well in extreme heat environment (to 1800° F., 982° C.) and provides strength, durability and protection from tear and distortion during field installation.
Also included in the gasket element 13 are an inner fire ring 29 and an outer fire ring 31. The purpose of the inner fire ring 29 and the outer fire ring 31 is to provide an additional mechanical seal of the hot exhaust gases, and to make the gasket assembly 11 more robust against installation damage. In one embodiment, the inner fire ring 29, and the outer fire ring 31 may be formed by an overlap 32 of the lower plate 27 and the upper plate 25. An air space 30 may be provided between the inner surface of the inner fire ring 29 and the core 23. It would be apparent to one skilled in the art that several types of fire ring configurations may be used, including but not limited to fire rings bonded to the core 23, fire rings that are separate components from the gasket element 13, and fire rings comprised of metallic O-rings.
In one embodiment, the width of the inner fire ring 29 (referenced as y1 in
Embodiments of the coolant seal 17 are best illustrated with reference to
Illustrated in
Preferably, the thickness of the coolant seal 17 is approximately equal to the thickness of the inner fire ring 29. This eases the field installation process and mitigates the risk of installation damage by eliminating the need to strike the seal with a hammer
When in use, the gasket assembly 11 provides an effective seal against leakage of coolant by means of the coolant seal 17. Additionally, the inner fire ring 29 and the outer fire ring 31 provide structural integrity that makes the gasket assembly 11 more robust against installation damage.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
