WO2005060516A2

WO2005060516A2 - Multi-layer gasket employing sealing rings

Info

Publication number: WO2005060516A2
Application number: PCT/US2004/039678
Authority: WO
Inventors: Robert F. Gorman
Original assignee: Cometic Gasket, Inc.
Priority date: 2003-12-02
Filing date: 2004-11-24
Publication date: 2005-07-07
Also published as: WO2005060516A3

Abstract

A multi-layer cylinder head gasket (A) for an internal combustion engine includes a central layer (10) and a pair of layers (12 and 14) positioned on opposite sides of the central layer. The layers of the gasket have one or more circular openings (20) configured to register with cylinder bore openings of the engine. A sealing ring (B) is secured to the central layer (10) to surround each of the circular opening (20) in the central layer (10). Each sealing ring (B) includes a resilient core (32) extending around the circular opening of the central layer and a jacket (30) housing the resilient core. The resilient core can include a helical spring.

Description

MULTI-LAYER GASKET EMPLOYING SEALING RINGS

Claim of Priority [0001] This application claims priority from U.S. Provisional Patent Application Serial No. 60/526,254, filed on December 2, 2003.

Background of the Invention [0002] Gaskets are often used as a seal between mating mechanical components. A common application of gaskets involves sealing between a cylinder head of an internal combustion engine and the intake and exhaust manifolds that connect to the cylinder head. A more rigorous sealing application exists between the adjoining surfaces of a cylinder head and an engine block, where leakage of fluids such as combustion gasses, oil, coolant, and the like must be prevented in the face of the high forces produced by the compression and ignition of combustion gasses, which act to separate the adjoining surfaces.

[0003] In the context of high-performance internal combustion engines, the seal between the cylinder head and engine block often is provided by gaskets formed from several individual metal layers having the appropriate openings to allow passage of fluids and mechanical components between the cylinder head and engine block. The layers of such gaskets typically are formed of stainless steel and are termed "multi-layer-steel" gaskets. Multi-layer-steel gaskets are well known in the art and are shown in such patents as U.S. Patent No. 5,803,462 and U.S. Patent No. 6,758,479, which are incorporated herein by reference.

[0004] Roll hardened stainless steel of the 300 series is often used as a material for the gasket layers. Stainless steel materials are known to possess the hardness and strength required for the active gasket layers. [0005] The cylinder head gasket is intended to be mounted between the engine block and the cylinder head of an engine, so as to provide sealing at the combustion chambers and sealing of fluid passages, particularly those that carry engine coolant and lubricating oil. The sealing conditions differ according to whether the sealing is against high temperature gasses of the combustion chamber or against these fluids located outside the combustion chamber. Currently, the active layers of multi-layer-steel gaskets (the layers in contact with the engine surfaces) typically have annular embossments that form bead-like structures around the cylinder openings. These embossments become elastically compressed when the cylinder head is bolted to the engine block to provide the required seal around the cylinders. [0006] In certain engine applications, separate sealing rings have been used instead of using multi-layer-steel gaskets. In these applications, the seal around the cylinder openings has been provided by spring-energized sealing rings positioned in grooves machined in the surfaces of the cylinder head and/or engine block. These sealing rings are formed from a metal jacket surrounding a core comprising a close-wound helical spring. The material used for the jacket is more ductile than the material forming the adjoining surfaces of the cylinder head and engine block. Each coil of the spring acts independently and allows the jacket to conform to surface irregularities on either adjoining surface and thereby provide a reliable seal. The spring is selected to have a specific compression resistance when the cylinder head is bolted to the block. As the bolts are torqued, the resulting specific pressure forces the jacket to yield and fill the imperfections in the adjoining surfaces while ensuring positive contact therewith.

[0007] The spring-energized sealing rings described above are of the type sold by Garlock Helicoflex of Columbia, South Carolina, a division of Coltec Industries Inc. The seal ensures a useful elastic recovery during service. Elastic recovery permits the seal to accommodate minor distortions in head/block joint due to temperature and pressure cycling. The compression and decompression cycle of the seal is characterized by the gradual flattening of a corresponding compression curve.

[0008] Previously, spring-energized sealing rings employed to seal around the cylinder openings have been used without a gasket, with O-rings and similar seals being utilized to seal fluid passages and the like at the cylinder head-block interface. These other seals also require machining of the adjoining surfaces to ensure proper alignment and location. [0009] The present invention combines sealing rings with a multi-layer- steel gasket. This novel combination provides the enhanced sealing of the sealing rings around the cylinder openings while eliminating the need to machine grooves for the rings. It also eliminates the need to use O-rings and the machining and preparation time associated with these additional seals. [0010] Employing the sealing rings as part of a multi-layer-steel gasket prevents bore distortion due to high clamping loads and cylinder pressures. Currently, multi-layer-steel gaskets typically can withstand between 1800 and 2000 psi of cylinder pressure without affecting bore distortion. By incorporating the sealing rings in the gasket, approximately 1000 additional psi of pressure can be withstood by the gasket without affecting bore distortion.

Summary of the Invention [0011] The present invention relates to gaskets. In particular, the present invention relates to a multi-layer-steel gasket in combination with sealing rings such as spring-energized sealing rings. A multi-layer-steel gasket typically has a metal center layer sandwiched between parallel metal outer layers. The gasket has one or more openings for the passage of engine coolant and/or lubricating oil and one or more bolt holes spaced from these openings. The gasket can be formed from several layers of flat metal plates made of steel or the like.

[0012] The gasket according to the present invention can have three layers of stainless steel. The stainless steel is provided for increased strength, its ability to rebound, and its corrosion resistance. The top and bottom outer layers of the gasket also can be embossed and coated on both sides with a fluoroelastomer rubber based material designed to meet the demands of a variety of harsh sealing environments, load conditions, and surface finishes. A center or shim layer of the gasket can be an uncoated stainless steel layer. The thickness of the center layer can be varied to meet certain performance requirements, such as adjusting the compression ratio of the engine. The composition of the gasket is designed to withstand shearing forces created by aluminum heads on the cast iron blocks, although it also is suitable for other applications, including aluminum heads and aluminum blocks and non- aluminum heads. The gasket promotes an even torque load across the sealing surface along for a measurable reduced poor distortion. [0013] The sealing ring includes an annular jacket of circular cross-section that can be formed of a nickel-based stainless steel alloy. When a spring- energized sealing ring is employed, the jacket encloses an annular resilient core that can comprise a helical spring formed of a high-strength alloy.- The sealing ring can further include a circumferential tab portion extending from the jacket in a radially outward direction.

[0014] In the disclosed embodiments of the gasket of this invention, the sealing rings are connected to the center layer of the multi-layer-steel gasket. An interference fit can be provided between each circular cylinder opening in the center layer and the associated sealing ring to provide proper positioning of the rings relative to the cylinder openings. The sealing ring also can be secured into place by spot welding the tab portion to the center layer of the gasket or by using an adhesive. In the disclosed embodiment, the top and bottom layers of the multi-layer-steel gasket are not in contact with the jacket portions of the sealing rings and are not embossed in the vicinity of the cylinder openings. The top and bottom layers of the gasket operate to provide sealing of coolant and oil passages in the conventional manner. [0015] The jacket portion of the sealing ring can be coated by a silver plating approximately 0.001-.002 inch in thickness. Because the silver plating is difficult to weld, there are advantages to plating only the portions of the jacket that provide sealing surfaces and leaving the tab portion as unplated nickel-based stainless steel. Several configurations can be provided for the sealing ring within the gasket. Each of these configurations includes a circumferential tab that extends radially outward from the jacket portion of the ring to provide a connection with the gasket.

[0016] Thus, in accordance with one embodiment of the invention, a multilayer cylinder head gasket for an internal combustion engine having at least one cylindrical bore opening has a central layer having a circular opening configured to register with the cylindrical bore opening and a pair of outer layers positioned on opposite sides of the central layer. Each of the outer layers has a circular opening configured to register with the cylindrical bore opening. The gasket further includes a sealing ring secured to the central layer and surrounding the circular opening in the central layer. The sealing ring includes an annular resilient core extending around the circular opening of the central layer and can include an annular jacket housing the resilient core. The annular resilient core can include a helical spring. [0017] In accordance with another embodiment of the invention, a multilayer cylinder head gasket for an internal combustion engine having a plurality of cylindrical bore openings has a first layer having a plurality of circular openings configured to register with the cylindrical bore openings. Second and third layers are interposed on opposite sides of the first layer. Each of the second and third layers has a plurality of circular openings concentric with the openings of the first layer. A plurality of sealing rings is secured to the first layer. Each of the sealing rings surrounds one of the circular openings in the first layer. Each of the sealing rings has a resilient core extending around the opening of the first layer and an annular jacket housing the resilient core. [0018] Other aspects of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description.

Brief Description of the Drawings [0019] The invention may take form in certain components and structures, the preferred embodiments for which will be illustrated in the accompanying drawings wherein:

[0020] FIGURE 1A is a top plan view of a multi-layer-steel gasket combined with sealing rings in accordance with a first embodiment of the present invention;

[0021] FIGURE 1 B is a side elevational view of the gasket of Figure 1A illustrating the layers of the gasket and the sealing ring; [0022] FIGURE 1C is a side elevational view of the gasket of Figure 1A illustrating an opposite side of the gasket and seal layers; [0023] FIGURE 2A is a top plan view of the sealing ring; [0024] FIGURE 2B is a side elevational view of the seal of Figure 2A along lines 2B-2B; [0025] FIGURE 2C is a cross-sectional elevational view of the sealing ring of Figure 2A;

[0026] FIGURE 3 is a side elevational view in cross-section of the inter- cylinder portion of the multi-layer-steel gasket shown in FIGURES 1A-1C; [0027] FIGURE 4 is a side elevational view in cross-section of the gasket's center layer and sealing rings having a crimping member in accordance with a second embodiment of the present invention; and,

[0028] FIGURE 5 is a side elevational view in cross-section of a gasket and sealing rings in accordance with a third embodiment of the present invention.

Detailed Description of the Disclosed Embodiments [0029] Referring now to the drawings wherein the showings are for purposes of illustrating the preferred embodiments of the invention only and not for purposes of limiting same, FIGURES 1A-1C illustrate a gasket A of a multi-layer-steel construction and having a center layer 10 sandwiched between parallel outer layers 12, 14. All three layers can be made from sheets of stainless steel. The outer layers (or top and bottom layers) can be made of sheets of stainless steel approximately 0.010 inch thick and are not embossed in the areas of the cylinder openings. The center layer can be approximately 0.020 inch thick to mate properly with the sealing ring currently used. The gasket is typically used in an internal combustion engine environment and is received between an engine block and a cylinder head (not shown).

[0030] The engine block has a cylinder that defines a combustion chamber. A cylinder liner typically lines the combustion chamber. The cylinder head is secured to the engine block by bolts (not shown) passing through holes 16 in the gasket to clamp the gasket between the engine block and the cylinder head with the openings in the head and block registering with the openings in the gasket.

[0031] The layers of the gasket also have a plurality of large circular openings 20 adapted to extend about the combustion cylinders of the internal combustion engine in precise registration. The edges of the openings in each layer of the gasket substantially coincide with each other. [0032] Away from the openings 20, the outer layers of the gasket are constructed as is conventional to provide sealing contact with the cylinder head and engine block around passageways for engine coolant, lubricating oil, fastening bolts and the like. The outer layers of the gasket can be coated on both sides with a fluoroelastomer rubber based material. [0033] In the disclosed embodiments of this invention, sealing rings eliminate the need for embossments around the combustion cylinder openings. A sealing ring B is shown as a component of the gasket of this invention in Figures 1A-1C and separately in Figures 2A-2C. The sealing ring includes a jacket 30 at least partially surrounding an annular resilient core 32. When sealing ring 30 is a spring-energized sealing ring, the annular resilient core 32 takes the form of a close-wound helical spring. Extending radially outward from the jacket is a circumferential tab 34 whose radial dimension can be varied according to the environment the sealing ring is used in. For example, for engines with close cylinder spacing, the tab can be trimmed shorter in the inter-cylinder spaces to avoid overlapping of the tabs. [0034] An example of the spring-energized sealing ring disclosed herein is Garlock Helicoflex's Model No. U-201590-1 , which would be applicable for an engine having a cylinder bore diameter of 4.200 inches. With reference to Figure 2C, it has a jacket outer diameter or overall axial thickness "t" of approximately 0.049 inch and a radial dimension or width "w" (measured from the radially inner edge of the jacket to the radially outer edge of the tab) of about 0.130 inch. The annular resilient core is a close-wound helical spring of high-strength alloy. The jacket can have a silver plating approximately 0.001- 0.002 inch thick provided only on the sealing portions of the ring, that is, not on the, tab. The tab is used to position and secure the ring within the cylinder openings in center layer 10 of the gasket. In the disclosed embodiment, the top and bottom layers 12, 14 of the gasket do not contact the jacket of the sealing ring, and the tabs of adjacent seal rings between adjacent bores of the gasket do not come into contact with one another.

[0035] Referring now to Figure 3, in a first configuration corresponding to that shown in Figures 1A-1C, the tabs 34 of adjacent sealing rings are provided on the same face of the center layer (either the top or bottom face). The tabs of the sealing rings are secured to the center layer to ensure that they are positioned properly relative to the combustion cylinder openings. The sealing rings can be fixed in place by spot welding or by an adhesive. The tabs do not overlap each other. The circular opening of the center gasket layer can be dimensioned to provide a clearance of approximately 0.001 inch relative to the radially outward edge of the jacket or spring to provide an interference fit of the sealing ring within the center layer's opening. The close tolerance also assists proper positioning of the sealing rings relative to the engine's combustion cylinders.

[0036] Referring to Figure 4, a second alternative is to provide one or more crimping members 36 connected to the sealing ring's jacket opposite the tab of the sealing ring. The crimping member is crimped downwardly onto the center layer of the gasket and thereby secures the sealing ring into position on the center layer of the gasket. This helps installation of the ring and might avoid the necessity of spot welding the sealing ring into place. In this configuration the tabs 34 of adjacent sealing rings also are on the same face of the center layer and do not overlap each other.

[0037] Referring now to Figure 5, in a third configuration, the sealing rings are provided so that the tabs 34 of adjacent sealing rings are on opposite sides of the center layer 10 of the gasket. The tabs of the sealing rings can be spot welded to the center layer of the gasket to fix their positions relative to the gasket or the sealing ring can be secured to the center layer of the gasket by an adhesive.

[0038] In the current configuration, the diameters of the circular openings 20 in all three layers of the gasket are the same. Alternatively, the diameters of the circular openings for the top and bottom layers of the gasket can be enlarged to provide a defined radial clearance between those layers and the non-tab portion of the sealing ring. An appropriate radial clearance would be about 0.020 inch.

[0039] In accordance with an alternate embodiment of the present invention, the coil spring resilient core of the sealing ring can be replaced with a tubular metal resilient core having the form of a metal O-ring. The configuration of the sealing ring otherwise would be substantially the same as that discussed above and as shown in Figures 2-5. [0040] The tubular metal core of this alternative sealing ring can be self- energizing by system pressure or be pressure filled for added resiliency. Sealing rings with tubular metal tubes can have advantages over helical spring-energized sealing rings in some engine applications and can vary in materials, wall thickness, and cross-section depending on load required. [0041] Examples of these tubular metal resilient cores are Garlock Helicoflex metal O-rings manufactured using different materials such as 300 series stainless steel, alloy 600, alloy X750 or other special alloys. Temperature, pressure, and corrosive aspects of the media determine which material is best suited for the application.

[0042] For self-energizing tubular metal cores, the surface of the tubular core exposed to the highest pressure, usually the inner periphery, is vented by small holes or slots. A sealing ring with a self-energizing tubular core allows the system pressure to enter the core, creating maximum specific pressure and reducing the pressure differential across the seal. Alternately, the tubular metal core can be pressure filled with an inert gas, for example, at 600 psi. At elevated temperatures, the gas pressure increases to offset the loss of strength in the tubing and specific pressure.

[0043] The tubular metal core or metal O-ring is part of a sealing ring that includes a jacket, such as jacket 30, which surrounds a portion of the metal O- ring. Extending radially outward from the jacket can be a circumferential tab, such as the tab 34 shown in Figures 2A-2C, whose radial dimension can be varied according to the environment the sealing ring is used in. For example, for engines with close cylinder spacing, the tab can be trimmed shorter in the inter-cylinder spaces to avoid overlapping of the tabs. The jacket configuration would be substantially the same as that shown in Figures 2A- 2C. The alternative arrangements shown in Figures 3, 4, 5 could also be used with the tubular metal core in lieu of a coil spring core. The sealing ring would perform in much the same manner as that described for the spring- energized sealing ring.

[0044] The invention has been described with reference to the disclosed embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations.

Claims

In the claims:

1. A multi-layer cylinder head gasket for an internal combustion engine having at least one cylindrical bore opening, comprising: a central layer having a circular opening configured to register with the cylindrical bore opening; a pair of outer layers positioned on opposite sides of said central layer, each of said outer layers having a circular opening configured to register with the cylindrical bore opening; and a sealing ring secured to said central layer and surrounding said circular opening in said central layer, said sealing ring including an annular resilient core extending around said circular opening of said central layer.

2. The gasket of claim 1 , wherein said sealing ring further includes an annular jacket housing said annular resilient core.

3. The gasket of claim 1 , wherein said annular resilient core comprises a helical spring.

4. The gasket of claim 2, wherein said jacket comprises at least one circumferential tab portion extending from said gasket in a radially outward direction.

5. The gasket of claim 1 , wherein said sealing ring is connected to said central layer via an interference fit with said circular opening.

6. The gasket of claim 4, wherein said sealing ring is connected to said central layer via welding said tab portion to said central layer.

7. The gasket of claim 2, wherein said jacket is coated by a silver plating between 0.001-0.002 inches in thickness.

8. The gasket of claim 4, wherein said tab portion is unplated nickel-based stainless steel.

9. The gasket of claim 1 , wherein said outer layers each comprise a sheet of stainless steel approximately 0.010 inch thick.

10. The gasket of claim 1 , wherein said central layer comprises a sheet of stainless steel approximately 0.020 inches thick.

11. The gasket of claim 1 , wherein said resilient core comprises a helically wound wire of high-strength alloy.

12. The gasket of claim 2, wherein said jacket has an axial thickness of approximately 0.049 inches.

13. The gasket of claim 12, wherein said jacket has a radial width of approximately 0.130 inches.

14. The gasket of claim 1, wherein said central layer includes a plurality of circular openings configured to register with a plurality of cylindrical bore openings in the engine.

15. The gasket of claim 14, further comprising a plurality of sealing rings, each of said sealing rings being secured to said central layer surrounding one of said circular openings.

16. The gasket of claim 15, wherein each of said sealing rings includes a resilient core extending around one of said circular openings of said central layer.

17. The gasket of claim 16, wherein each of said sealing rings further comprises an annular jacket for housing said resilient core of said respective sealing ring.

18. The gasket of claim 17, wherein each of said resilient cores comprises a helical spring.

19. The gasket of claim 18, wherein each of said jackets comprises at least one circumferential tab portion extending from said jacket in a radially outward direction.

20. The gasket of claim 19, wherein each of said tab portions is affixed to a surface of said central layer.

21. The gasket of claim 20, wherein said tab portions of adjacent sealing rings do not overlap each other.

22. The gasket of claim 4, wherein said jacket includes a crimping member on a side of said jacket opposite to said tab portion.

23. The gasket of claim 19, wherein each of said jackets comprises a crimping member on a side of said jacket opposite to said tab portion.

24. The gasket of claim 19, wherein said tab portions of adjacent sealing rings are affixed to opposite surfaces of said central layer.

25. A multi-layer cylinder head gasket for an internal combustion engine having a plurality of cylindrical bore openings, comprising: a first layer having a plurality of circular openings configured to register with the cylindrical bore openings; second and third layers interposed on opposite sides of said first layer, each of said second and third layers having a plurality of circular openings concentric said openings of said first layer; and a plurality of sealing rings secured to said first layer, each of said sealing rings surrounding one of said circular openings in said first layer, and each of said sealing rings including an annular resilient core extending around said respective circular opening of said first layer.

26. The gasket of claim 25, wherein each of said sealing rings further includes an annular jacket for housing one of said annular resilient cores.

27. The gasket of claim 26, wherein said jackets include at least one circumferential tab portion extending from said jacket in a radially outward direction.

28. The gasket of claim 25, wherein each of said sealing rings is connected to said first layer via an interference fit with said respective circular opening.

29. The gasket of claim 25, wherein said first layer is thicker than said second and third layers.