Patent Application
20080237998
Described herein is a gasket that may be used for sealing an interface between a cylinder head and an engine block of an engine and/or that may be used for sealing an interface between a cylinder head and an exhaust manifold of an engine.
Gaskets made of a metal material are employed for sealing an interface between a cylinder head and a cylinder block and/or an interface between a cylinder head and an exhaust manifold of an engine. Apertures in the gasket are typically provided to cooperate with combustion chambers, water passages, oil passages, exhaust gas passages or other fluid flow passages to allow fluid flow therethrough.
These gasket openings may have a structure that improves sealing around the openings.
Gaskets must withstand extreme pressure variations within and adjacent engines to prevent coolant leakage, resist rust, corrosion and, in many cases, meter fluid flow. Gaskets must also seal fluid passages extending through the engine block, the cylinder head and/or the exhaust manifold while resisting chemical reaction, allowing for lateral and vertical head movement as the engine heats and cools, and still be flexible enough to seal minor surface warpage while being stiff enough to maintain adequate gasket compression, as well as fill small machining marks that could lead to gasket leakage or failure, and withstand forces produced by engine vibration.
Further, gaskets must withstand extreme temperature variations inherent in internal combustion engine applications. During engine operation, inner edges of the cylinder head gaskets may be exposed to combustion flame temperatures from 2,000 to 3,000 degrees Fahrenheit. Accordingly, engine parts resting at subzero temperatures may be subjected to temperatures rising above 400 degrees Fahrenheit after only a few minutes of engine operation.
Known gaskets generally do not provide adequate sealing properties across the entire temperature range typical of internal combustion engine applications. As an engine warms up, thermal expansion of the engine head may create space in between the block and head and between the head and the exhaust manifold. This reduces an interface pressure applied by the cylinder head and engine block to the cylinder head gasket, thereby reducing the effectiveness of the seal provided by the gasket. The same is true regarding an interface pressure applied by the head and the exhaust manifold to the exhaust manifold gasket. After engine operation ceases, and especially during storage in cold conditions, thermal contraction of the block and head may significantly reduce space for the gasket, thereby greatly increasing pressure applied to the gasket by the block, head and/or exhaust manifold, especially at outer areas of the gasket. This may significantly reduce the ability of the metal gasket to spring back to its designed height upon thermal expansion of the engine, such as during warm-up. Further, thermal contraction of the engine block, head and/or exhaust manifold may even crush features formed in the gasket entirely. This significantly reduces the effectiveness of the gasket in sealing the head/block and the head/manifold interface. Accordingly, there is a need for a gasket which can seal the interface between an engine block and head and the interface between the head and the exhaust manifold more effectively over many engine warm-up and cool-down cycles.
A gasket is disclosed. An illustrative embodiment of the gasket may include a plate with at least one aperture formed therein, a wave portion or plurality of ridges formed in the plate adjacent an edge of the plate, and a half-bead or ramp portion formed adjacent the edge.
Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
Turning now to
Turning now to
Gasket 10 may be a Multi-Layer Steel (MLS) gasket, as generally shown in the Figures, including an upper layer 18a, an intermediate layer 20, and a lower layer 18b, wherein each of the upper and lower layers 18 are formed of a steel material. In other embodiments, gasket 10 may include additional layers, i.e., further intermediate layers and steel layers sandwiched around upper and lower layers 18.
In still other embodiments, gasket 10 may be a single layer gasket, i.e., gasket 10 includes a single layer 18, e.g., either upper layer 18a or lower layer 18b, and is provided without intermediate layer 20.
In embodiments where gasket 10 is an MLS gasket, both upper layer 18a and lower layer 18b have various features formed therein which generally correspond to features formed in the other layer. For example, as shown in
The wave portion 22 generally provides cross-sectionally projecting waves that extend along edge 11 of gasket 10, e.g., about oil passage 16. Half-bead portion 24 similarly extends along edge 11. A transition region 36, which may be generally flat, may be disposed between wave portion 22 and half-bead portion 24.
Portion 22 generally inhibits crushing of gasket 10, and in particular of half-bead portion 24, when pressure exerted upon gasket 10 is at a maximum, e.g., during cold temperature conditions. Half-bead portion 24 generally maximizes sealing of an engine block and head interface during high liftoff conditions, e.g., high temperature conditions.
The shape of the portion 22 and half-bead portion 24 may be selected from any commonly known geometric shape and may be varied to achieve uniform sealing stresses in both layers. Half-bead portion 24 may be disposed between portion 22 and edge 11, as is shown in the Figures. Alternatively, portion 22 may be disposed between half-bead portion 24 and edge 11. Gasket 10 may provide an effective seal for apertures such as oil passage 16 when half-bead portion 24 is between portion 22 and edge 11, such that half-bead portion 24 provides a primary seal about the aperture, and portion 22 generally prevents half-bead portion 24 from being crushed during high-pressure gasket conditions. Alternatively, gasket 10 may provide an effective seal for exhaust gases passing through apertures in an exhaust manifold gasket applications when portion 22 is provided between half-bead portion 24 and edge 11.
Portion 22 generally includes a plurality of ridges, waves, or undulations which project cross-sectionally away from edge 11 in each of upper and lower layers 18. Each ridge or undulation of upper and lower layers 18 may define an outer surface 26a, b, c, d (collectively, 26) for engaging engine surfaces (not shown in
Outer surfaces 26 and outer valley surfaces 27 generally define a depth A of each ridge or undulation on an outer side 30a of upper layer 18a, and an outer side 30b of lower layer 18b. Similarly, inner surfaces 28 and inner valley surfaces 29 define a depth B of each ridge or undulation on an inner side 31a of upper layer 18a and an inner side 31b of lower layer 18b. Depth A and depth B are both preferably at least 0.03 millimeters, but may be any distance greater than 0.03 millimeters that is convenient. In one embodiment, both depth A and B are about 0.07 millimeters. Depth A and B are preferably equal, but may be different. Further, material forming processes may result in slight variations between depth A and depth B.
As shown in
As described above, portion 22 generally prevents gasket 10 from being crushed when pressure exerted upon gasket 10 an engine block and head is at a maximum, e.g., during cold start conditions. An ability of portion 22 to resist crush may be modified by employing a larger or smaller number of ridges, or increasing or decreasing depths A and B. Further, crush resisting properties of gasket 10 may be adjusted by altering a shape of ridges included in portion 22. For example, gasket 10′ shown in
As described above, half-bead portion 24 generally increases sealing capabilities of gasket 10 during high lift off conditions, e.g., high temperature conditions. Half-bead portion 24 generally includes an inclined portion 34a,b (collectively, 34) leading upward from transition regions 36 to upper regions 32a,b (collectively, 32). Alternatively, inclined portions 34 may be inclined in an opposite direction as that shown, i.e., inclined portion 34a may slope “upward” (with inclined portion 34b sloping “downward”) in
MLS gasket 10 generally includes an intermediate layer 20, and may include any other number of additional layers that is convenient. Intermediate layer 20 may be formed of any known materials, including 301SS, NiZn Steel, 409SS, 201SS, and 304ss materials. Further, a thickness of intermediate layer 20 may be any thickness that is convenient, depending on the operating thickness defined by the engine block and heads (not shown), but is preferably at least 0.08 millimeters.
Other design parameters of gasket 10 may be varied to control a seal operating thickness of gasket 10. For example, a width, depth, and/or shape of portion 22 and half-bead portion 24 may be varied, as well as an overall thickness of upper and lower layers 18 and intermediate layer 20. Such control provides the ability to easily customize gasket 10 for a particular gasket application. In some known embodiments, portion 22 has a width from 1.025 millimeters (mm) to 1.06 mm. Additionally, a number of waves formed in portion 22 may be varied to adjust an overall stiffness of gasket 10. For example, increasing a number of waves formed in a given width of portion 22 may increase an overall stiffness of gasket 10, and vice versa. Additionally, gasket 10 may also include an elastomeric coating having a thickness between 0.001 millimeters and 0.05 millimeters to enhance sealing provided by gasket 10. However, thicker coatings may be used. In one embodiment, a Dana Corporation FKM coating is utilized; however, other like coatings may be employed.
Each of portion 22 and half-bead portion 24 may be formed in upper and lower layers 18 of gasket 10 by any known method. In one embodiment, portion 22 is stamped into a generally flat blank, and half-bead portion 24 is subsequently stamped into the blank. A stamping operation for forming portion 22 may be generally similar to that of a coining operation. A recovery potential of half-bead portion 24 may be generally increased by employing a greater tooling height.
Turning now to
When gasket 10 is installed, wave portion 22 and half-bead portion 24 may elastically deform in a spring-like fashion, as shown in
Referring now to
The gasket 10″ is substantially identical to gaskets 10 and 10′ described above and depicted in
Fasteners, such as bolts, may be located through the fastener apertures to selectively secure the manifold 202 to the head 200.
The cylinder head 200 and exhaust manifold 202 have opposed surfaces 204, 206 that require proper sealing near edge 11″ of the gasket 10.″ Edge 11″ may be that of a fluid passage or an outer perimeter of the cylinder head 200 and exhaust manifold 202. Gasket 10″ is held between cylinder head 200 and exhaust manifold 202 and generally seals clearances between the opposed surfaces 204, 206 thereof.
When the gasket 10″ is installed between the cylinder head 202 and the exhaust manifold 202, wave portion 22″ and half-bead portion 24″ may elastically deform in a spring-like fashion. Portion 22″ generally creates a uniform sealing pressure pattern throughout portion 22″ where load is desired. When the cylinder head 202 and the exhaust manifold 202 exert a maximum pressure upon gasket 10″, such as during storage of the engine in cold temperatures, portion 22″ generally resists crushing of gasket 10.″ In particular, half bead portion 24″ resists such crushing, thereby increasing springback capabilities of half bead portion 24″ when the engine transitions to a higher lift-off condition, such as during engine warm up. Accordingly, gasket 10″ may provide effective sealing of a cylinder head/exhaust manifold 200, 202 interface during both high lift-off and high compression conditions.
With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain approaches, examples or embodiments, and should in no way be construed so as to limit the claimed invention.
Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the invention should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the arts discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the invention is capable of modification and variation and is limited only by the following claims.
All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those skilled in the art unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.
