Patent Application
20060022415
1. Technical Field
The subject invention relates generally to static sealing assemblies, and more particularly to those having an elastomeric sealing bead extending upwardly from a first component to create a seal with a second component.
2. Related Art
Various static sealing assemblies are known for creating a fluid-tight seal between mating components. One common type of static seal is a gasket which typically includes a carrier formed of a metal, such as steel, or plastics material on which elongated beads of elastomeric sealing material are adhered. The carrier provides the rigid framework or backbone for properly locating and supporting the sealing beads which, when the components are clamped together, are compressed under pressure to form the fluid-tight seal. Another type of static seal omits the carrier such that the sealing bead is applied directly to the sealing face of one of the two components, but otherwise operates in the same manner to form a seal under compression.
One concern with static seals of either type is that the elastomeric sealing bead not be overcompressed to the point where it ruptures or moves out of position to impair the desired sealing characteristics of the seal. One approach to controlling over deformation of the sealing bead is to mount the sealing bead in a groove of the carrier or sealing face. The groove is shaped and dimensioned relative to the sealing bead to provide a void or air space adjacent to the sealing bead. When deformed under compression, the sealing bead is displaced laterally to fill or partially fill the voids with only a small portion of the sealing bead extending above the groove to provide a fluid-tight seal between the components. Such grooves must have sufficient depth to accommodate the bulk of the sealing bead when in the compressed state. This is particularly problematic with gasket applications since it calls for a fairly thick carrier to accommodate the deep groove for the sealing beads. Not all applications can accommodate such a thick carrier, particularly certain automotive applications where there is a constant trend toward making engines and related components more compact, allowing for less and less space between mating components to achieve a seal. One additional draw back to the deep groove approach for protecting sealing beads on carriers against over-compression is that the deep groove in combination with a thinner carrier reduces the physical strength of the carrier and may impair the sealing characteristics of the seal.
Another approach to controlling over-compression is to build voids or empty spaces into the cross section of the sealing beads, for example providing a void or open channel on either side of a central sealing projection of the bead that runs the length of the bead. Under compression, the central projection is deformed into the voids. One disadvantage to this approach is that the seal material is displaced in opposite directions, putting undue stress on the gasket material which could lead to undesirable fatigue or possibly rupture over time.
The subject invention provides a sealing assembly for creating a seal between a first component and a second component. The first component has a first sealing surface with a sealing bead extending upwardly therefrom and the sealing bead has a predetermined original uncompressed height measured from the first sealing surface. The second component presents a second sealing surface to create the seal when the first and the second components are brought into mating engagement. When the first and the second component are in mating engagement, the sealing bead compresses at most 40% of the predetermined original height. The compression of the sealing bead by the second sealing surface creates the seal between the first sealing surface, the sealing bead, and the second sealing surface.
The subject invention provides a sealing assembly that overcomes or greatly minimizes the deficiencies of the known prior seal assemblies discussed above. A seal assembly constructed according to the present invention has greater longevity as a result of the limited compression of the sealing bead (i.e., at most 40%). By designing a seal that operates at 40% or less compression, the present invention overcomes the challenges of prior seals by avoiding cracking or rupturing and loss of elasticity at compressions exceeding 40%. The low compression seals of the present invention further enable those who service a vehicle or clamped components to reuse the seal since its integrity has not been compromised by prolonged over-compression as with the prior seals which must be routinely replaced at time of service.
These and other advantages 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 wherein:
A sealing assembly constructed according to a first presently preferred embodiment of the invention is shown generally at 10 in
Referring to
In the preferred embodiment, a groove 24 is formed in the first sealing surface 16 having a fixed groove depth 26 and a groove width 27. It is to be understood by those skilled in the art that the subject invention contemplates molding the sealing bead 18 directly to the first component 12 without including the groove 24. However, the presence of the groove 24 is preferred. The groove depth 26 must be large enough to receive the sealing bead 18 and still have adequate physical properties. The groove depth 26 is preferably selected to be no more than one-half of the predetermined height 20 of the sealing bead 18. In the preferred embodiment, the sealing bead 18 is molded into the groove 24 and a base portion 36 of the sealing bead 18 completely fills the groove 24 in the relaxed, uncompressed state of the sealing bead 18.
With reference to
The relative dimensions and volumes of the components, the recess 30 and the sealing bead 18 allow at most a 40% reduction in the height of the sealing bead 18 at full compression (
Referring back to
The predetermined height 20 of the sealing bead 18 also contributes to the improved longevity and to the limited compression. The sealing portion 38 may have various shapes but preferably has either one of a generally triangular cross-section or a generally frustoconical cross-section. The predetermined height 20 is preferably defined as a height of the sealing portion 38 as measured from the base portion 36. For example, if the base portion 36 is flush with the first sealing surface 16 of the first component 12, then the predetermined height 20 is defined from the first sealing surface 16 to the tip 40 of the sealing bead. The sealing portion 38 has a base 42 that is preferably flush with the base portion 36 and a top 40 that terminates the sealing bead 18. When the sealing bead 18 is triangular shaped, then the top 40 is the tip of the triangle, as in
In the preferred embodiment, the base 42 has a base width 44 greater than the top 40 and less than the base portion 36. A first side 46 and a second side 48 extend upwardly transverse from the base 42 toward the top 40 and interconnects the base 42 of the sealing bead 18 to the top 40 of the sealing bead 18. This occurs when the sealing portion 38 is either triangularly shaped or frustoconically shaped.
Since the compression of the sealing bead 18 is controlled by the recess 30, the groove 24 in the first component 12 can be smaller. This also allows the first component 12 to be formed of different materials and smaller thicknesses can be successfully employed. In the embodiment when the sealing bead 18 is molded directly to the first component 12 without the groove 24, the first component 12 can have a very small thickness.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. The invention may be practiced otherwise than as specifically described within the scope of the appended claims.
