SHAFT SEAL WITH RETENTION FEATURES AND OVERMOLDED SEAL COMPONENT

A seal component for a shaft seal assembly includes an elastomeric element and a substrate, wherein the seal component has an over-molded configuration in which the elastomeric element is over-molded onto the substrate. In one embodiment, the elastomeric element includes a pair of flexible arms that are compressible about an apex to energize the seal component. In another embodiment, the shaft seal assembly includes twist lock retention features for retaining the seal component within the housing structure. The seal component includes a plurality of locking features, and a plurality of cooperating locking slots is provided in the housing structure that respectively receive the locking features of the seal component. Specifically, when the seal component is rotated relative to the housing structure from an initial position to a second locked position, the locking features are compressed within the locking slots of the housing structure in the second locked position.

DETAILED DESCRIPTION

An exemplary embodiment of an enhanced seal component is depicted inFIGS. 2-4, in which like structures are identified by common reference numerals.FIG. 2is a schematic diagram depicting a perspective view of a portion of a seal component for use in a shaft seal assembly with an over-molded configuration.FIG. 3is a schematic diagram depicting a perspective cross-sectional view of a portion of a seal component ofFIG. 2identified by the oval A, andFIG. 4is a schematic diagram depicting a perspective cross-sectional view of a portion of a seal component ofFIG. 2identified by the oval B.

FIGS. 2-4depict a seal component36with an over-molded configuration for use in a shaft seal assembly. The seal component may extend circumferentially substantially to form a ring structure such as may be employed, for example, in a front crank shaft seal and like applications as referenced above. The seal component36includes an elastomeric element38over-molded onto a substrate40. The elastomeric element38may be made of suitable flexible materials that are used in various shaft seal applications. Suitable materials include, for example, various fluoro-elastomers, poly-acrylic materials, ethylene-acrylic materials, and like materials that are suitable to withstand the exposure to high pressures and extreme temperatures of typical applications. The substrate40may be made of suitable more rigid or semi-rigid materials that also are used in various shaft seal applications. The substrate40may be formed of rigid or semi-rigid plastic or metal materials, and acts as a stiffener element for controlling in part the degree of compressibility of the elastomeric element38. For front crank shaft seals, rigid nylon-based plastic materials commonly are employed for the substrate.

Referring more specifically to the close-up views depicted inFIGS. 3 and 4, to provide an over-molded configuration, the elastomeric element38defines an over-molding recess42, and the substrate40includes an over-molding extension44. The over-molding recess42receives the over-molding extension44. In this manner, although the elastomeric element38is compressible, the substrate40via the over-molding extension44acts as a stiffener element for controlling in part the degree of compressibility of the surrounding elastomeric element38.

As part of the manufacturing of the seal component36, therefore, the elastomeric element38is over-molded onto the substrate40and chemically bonded where the over-molding recess42receives the over-molding extension44. The chemical bonding may be aided by a heat-activated adhesive material that bonds the over-molding recess42of the elastomeric element38to the over-molding extension44of the substrate40. This over-molding of the elastic material over an extension portion of the substrate provides for enhanced seal performance as compared to conventional configurations for incorporation of stiffening elements into the elastomeric material.

The elastomeric element38of the seal component36is configured to provide an energized seal with a cooperating housing structure to form a complete shaft seal assembly. As seen best with reference to the close-up views ofFIGS. 3 and 4, the elastomeric element38includes a pair of flexible arms46and48. The flexible arms46and48may be connected about an apex50adjacent the over-molding recess42so as to form a substantially “V” or “U” shaped configuration. With such configuration, the arms46and48generally are compressible about the apex50toward the substrate40so as to provide an energizing effect. In exemplary embodiments, at least one of the arms (see, for example, arm48ofFIG. 2) may define a spring recess52. The spring recess52is configured to receive a spring53shown specifically inFIG. 2, (not shown inFIGS. 3 and 4) for providing an enhanced energizing effect.

FIG. 5is a schematic diagram depicting a perspective view of a seal component/housing assembly54, including the seal component36ofFIGS. 2-4and a housing structure56.FIG. 6is a schematic diagram depicting a perspective cross-sectional view of a portion of the seal component/housing assembly ofFIG. 5. The assembly may, for example, form part of a front crank shaft structure and like applications as referenced above.

The housing structure56may have a variety of configurations. In the particular example ofFIGS. 5 and 6, the housing structure56includes an outer housing component58to which the seal component36is fixedly attached. The seal components may be fixed by any suitable means, such as adhesives, mechanical fastening, and the like. The housing structure56also may have an inner housing component60, which in the example ofFIGS. 5 and 6is a central cylindrical element that rises above the remaining portions of the housing structure. As best seen in the cross-sectional view ofFIG. 6, a gap62is present between the seal component36and the inner housing component60. As further explained below, the gap62is configured to receive a cap structure that extends over at least a portion of the housing structure56.

FIG. 7is a schematic diagram depicting a perspective view of a shaft seal assembly70including the seal component/housing assembly ofFIGS. 5-6and a cap structure72.FIG. 8is a schematic diagram depicting a cross-sectional view of a portion of the shaft seal assembly70ofFIG. 7. The shaft seal assembly70includes the seal component36and the housing structure56. The cap structure72is received in the gap between the seal component36and the inner housing component60of the housing structure56. In this manner, the seal component36provides a seal between the cap structure72and the outer housing component58of the housing structure56. The cap structure then extends over at least a portion of the housing structure.

The seal is generated as follows. As referenced above, the seal component36includes the elastomeric element38over-molded onto the rigid or semi-rigid substrate40. The elastomeric element38of the seal component36is configured to provide an energized seal against an outer face74of the cap structure in the complete shaft seal assembly. In the assembled configuration, the arms46and48of the seal component are compressed about the apex50toward the substrate40so as to be energized against the outer face74of the cap structure72, so as to provide an energizing effect against the cap structure. As the seal is compressed further, the spring53also may become compressed between the elastomeric element and the substrate for providing a further enhanced energizing effect of the seal. The over-molding of the elastomeric element38onto the substrate40provides an enhanced seal effect by providing an appropriate balance between seal compressibility with some rigidity to strengthen the overall seal integrity.

FIGS. 9-14depict an alternative embodiment of a shaft seal configuration, which also is suitable, for example, for front crank shafts seals and like applications. In the embodiment ofFIGS. 9-14, a specialized retention feature is provided in the form of a twist lock retention feature. Similarly to the above, the twist lock retention feature avoids the need for an undercut to be machined in the application housing.

FIG. 9is a schematic diagram depicting a perspective view of a seal component100for use in a shaft seal assembly containing a twist lock retention feature. As further detailed below, the seal component includes an elastomeric element that has a plurality of twist lock retention locking features configured to be received in a portion of a housing structure of the shaft seal assembly, wherein when the seal component is rotated relative to the housing structure from an initial position to a second locked position, the locking features are retained within the receiving portions of the housing structure in the second locked position.

The seal component100includes an elastomeric element102bonded to a substrate104. The elastomeric element102may be made of suitable flexible materials similarly to the elastomeric element38above. Suitable materials include, for example, various fluoro-elastomers, poly-acrylic materials, ethylene-acrylic materials, and like materials that are suitable to withstand the exposure to high pressures and extreme temperatures of typical applications. Similarly, the substrate104may be made of suitable more rigid or semi-rigid materials comparably to the substrate40above. The substrate104may be formed of rigid or semi-rigid plastic or metal materials (steel for example), and acts as a stiffener element for controlling in part the degree of compressibility of the surrounding elastomeric element102. For front crank shaft seals, rigid nylon-based plastic materials commonly are employed for the substrate.

Similarly to the previous embodiment, the elastomeric element102is over-molded onto the substrate104. In exemplary embodiments, in the over-molding process the elastomeric element102may be chemically bonded to the substrate104. A suitable chemical bond may be achieved by employing a heat-activated adhesive material as are known in the art. The seal component100may be formed by a co-molding process in which the components102and104are molded in a unitary process with the heat-activated adhesive. The chemical bond in the embodiment ofFIG. 9is enhanced by the over-molding of the elastomeric element102onto the substrate104, similarly to the over-molding described as to the seal component ofFIGS. 2-4.

As seen inFIG. 9, the elastomeric element102has an outer diameter106onto which there are formed a plurality of rib structures108. As further explained below, the seal component100including the elastomeric element102in part is held against or within an internal bore defined by an application housing structure of the shaft seal assembly, particularly by the frictional forces of the rib structures108against such internal bore of an inner diameter surface of the application housing structure (not shown inFIG. 9).

Referring again toFIG. 9, the elastomeric element102further includes a top face110having thereon a plurality of locking features112. In the example ofFIG. 9, each locking feature112is an elongated ridge that extends above the top face110. Each locking feature has a curvature that substantially follows the curvature of the ring configuration of the elastomeric element102, and has two opposite rounded ends114spaced apart by a first length L1, and a first uncompressed width W1that is associated with the locking mechanism. As further explained below, when the seal component is rotated relative to the housing structure from the initial position to the second locked position, the elongated ridges are compressed within the receiving portions of the housing structure in the second locked position.

It will be appreciated that the precise shape of the locking features may be varied. In addition, the example elastomeric element102ofFIG. 9includes three locking features112spaced equidistantly about the circumference of the elastomeric element, although the precise number and spacing of the locking features also may be varied.

FIG. 10is a schematic diagram depicting a bottom view of an application housing structure116for use with the seal component100in a shaft seal assembly containing a twist lock retention feature.FIG. 11is a schematic diagram depicting a top view of the application housing structure ofFIG. 10. As explained in more detail below, the locking features of the seal component100are configured to be received in a portion of the housing structure116in an initial position and a second locked position. When the seal component is rotated relative to the housing structure from the initial position to the second locked position, the locking features are retained within the receiving portions of the housing structure in the second locked position.

The application housing structure116has a ring structure that is configured to fit over the elastomeric element102of the seal component100in a manner comparable to a cap configuration. The application housing structure116defines an internal bore118(seeFIG. 10) that is configured to receive the rib structures108of the elastomeric element102as referenced above. As also referenced above, conventional shaft seal configurations additionally may include an undercut precisely machined into the application housing for a retention feature, but the twist lock retention feature of the current invention avoids the need for such undercut.

The application housing structure116is formed of a rigid or semi-rigid material, such as a rigid or semi-rigid plastic or metal. As referenced above, for front crank shaft seals, rigid nylon-based plastic materials commonly are employed. It is desirable that the material used to form the application housing structure is the same as or similar to the material used for the substrate104of the seal component100. In this manner, thermal expansion rates of the application housing structure and substrate of the seal component will substantially match, which aids in maintaining the integrity of the seal.

The application housing structure116further includes a top face120that has a plurality of locking slots122. The locking slots122are of a number that equals the number of locking features112of the elastomeric element102. The locking slots122also are positioned about the top face of the application housing structure such that each locking slot122is configured to receive a corresponding or respective one of the elongated ridge locking features112. Each locking slot122has two opposite rounded first and second ends124and125spaced apart by a length L2, which is larger than the length L1of the locking features112. In exemplary embodiments, the length L2of the locking slots122is approximately twice the length L1of the locking features112. When the seal component is rotated relative to the housing structure from the initial position to the second locked position, the elongated ridge locking features move within the respective locking slots along the second length and are compressed within the locking slots of the housing structure in the second locked position.

The application housing structure also may include additional holes126for fluid flow, such as for oil or other lubricant materials, and draining.

As part of the twist lock retention feature, the width of each locking slot122gradually decreases from the first end124toward the second end125. In particular, each locking slot has a second width W2in the vicinity of the first end124, and decreases to a third width W3in the vicinity of the second end125. In addition, relative to the first uncompressed width W1of the locking features112, the three widths are slightly varied and satisfy the relationship W3<W1<W2.

The varying widths provide for the twist lock retention feature as follows.FIG. 12is a schematic diagram depicting a top perspective view of a shaft seal assembly200containing a twist lock retention feature.FIG. 12depicts the seal component100, including the elastomeric component102and substrate104, positioned within the application housing structure116. Like features are labeled the same inFIG. 12as in the previousFIGS. 9-11. Reference is made to allFIGS. 9-12in demonstrating the basic mechanism of the twist lock retention feature.

During assembly of the shaft seal assembly200, the application housing structure116is placed over the seal component100in a manner such that the rib structures108of the elastomeric component102are compressed within the internal bore118to provide a frictional force between the rib structures and the internal bore. In addition, each elongated ridge locking feature112is positioned within a respective locking slot122in the first end124of such respective locking slot. This position is referred to as an initial or unlocked position. Because the second width W2of first end124of the locking slot is greater than the first uncompressed width W1of the locking feature112, the locking feature112fits readily within the locking slot122in a relatively loose or unlocked manner. Then, seal component100is rotated, i.e., twisted, relative to the housing structure116(the motion is relative, so it does not matter which component actually moves) such that the elongated ridge locking features112move within the locking slots122along the greater second length L2of the locking slots until each locking feature112is positioned within a respective locking slot122in the corresponding second end125. This position is referred to as a second or locked position. Because the third width W3of the second end125of the locking slot is less than the first uncompressed width W1of the locking feature112, the relative motion of the rotation or twisting action compresses each locking feature112as each locking feature moves along length L2into the smaller width region of the each respective locking slot122. In this manner, the locking features112are compressed and fit tightly within the locking slots112in the second position in a locked manner.FIG. 12specifically depicts the shaft seal assembly200in the locked position in which the locking features are compressed within the second ends125of the corresponding locking slots122. In the initial or unlocked position, the locking features112would be adjacent the first ends124of the corresponding locking slots122.

FIG. 13is a schematic diagram depicting a side cross-sectional view of a portion of the shaft seal assembly200ofFIG. 12, as the shaft seal assembly would be configured within an application assembly210. The application assembly210, for example, may be a portion of an engine assembly or other suitable application in which the shaft seal assembly200may be used.

As seen inFIG. 13, the substrate104has a plurality of extension portions105(one is shown in the cross-section view ofFIG. 13), and each of the plurality of the extension portions105extends into the elastomeric component102, and particularly extends into an internal recess defined by a respective one of the plurality of locking features112. In this manner, although the elastomeric component102is compressible, similarly to the previous embodiment, the substrate104acts as a stiffener element for controlling in part the degree of compressibility of the surrounding elastomeric element102.

As part of the manufacturing of the seal component100, therefore, as referenced above the elastomeric component102is over-molded substrate104and chemically bonded as described above. As part of such over-molding process, the elastomeric material is co-molded over the extension portions105. The bonding may be aided by a heat-activated adhesive material that bonds the elastomeric component102to the extension portion105of the substrate104. This over-molding of the elastic material over an extension portion of the substrate provides for enhanced seal performance as compared to conventional configuration for incorporation of stiffening elements into the elastomeric material.

The substrate104also may have at least one flange128(which may be a plurality of flanges128, although only one is seen in the cross-section view ofFIG. 13) that extends laterally from a bottom surface the substrate104of the seal component100. As further explained below, the flange128has a contact surface that is configured to prevent further rotation beyond the second locked position.

FIG. 13further depicts the outer diameter106of the elastomeric element102containing the plurality of rib structures108. As referenced above, seal retention is aided in part by the frictional forces of the rib structures108that are compressed within or against the internal bore118of application housing structure116. Similarly to the previous embodiment, two rib structures118are included with significantly larger contours than is conventional, although the precise number and shape may be varied. This results in the seal component100having an increased volume of compressible material as compared to the conventional configurations. Again, this added compressibility requires fewer rib structures for retaining the seal component within the bore, and also aids the twist lock retention features in securing the seal components.

Referring again toFIG. 13, each locking feature112has opposite sides130that may define concave recesses132. The locking slots122of the application housing structure116further may include ridges134that are configured to be received within the concave recesses132. The cooperation of the concave recesses132and ridges134further enhances the integrity of the twist lock retention mechanism.

FIG. 14is a schematic diagram depicting a bottom perspective view of the shaft seal assembly200ofFIGS. 12 and 13, containing the described twist lock retention feature. As seen inFIG. 14, the plurality of flanges128referenced above each is contiguous or extends from a bottom surface134of the substrate104. In addition, the plurality of flanges108each includes a contact surface136. The application housing structure116also has a bottom surface138that has at least one, or a plurality of, rotation recesses140spaced apart from and defined by at least one or a plurality of walls142. Each wall142ends in a blocking surface144. As seen inFIG. 14, as the seal component is rotated relative to the application housing structure (or vice versa) from the initial unlocked position to the second locked position, each flange128moves within a respective rotation recess140. In the second locked position, which is the position depicted inFIG. 14, a contact surface136of each flange is pressed against a blocking surface144of a respective wall142. Further rotation beyond the second locked position is thus prevented by the contact surfaces reaching the blocking surfaces, which prevents over-torque of the shaft seal assembly200that otherwise could damage the seal components. The substrate104also may include at least one installation hole146for receiving an installation tool, such as a ratchet or like tool to facilitate installation.

The described twist lock retention feature provides an enhanced shaft seal structure as compared to conventional configurations. The components are readily molded and assembled, and provide effective seal retention without the need for a precisely machined undercut within the bore of the application housing structure. The described twist lock retention feature thus provides better retention with more simply manufactured components as compared to conventional shaft seals.

As referenced above, in the embodiments incorporating the twist lock retention features, the seal component100is formed by over-molding the elastomeric element102onto the substrate104to chemically bond the elastomeric material to the substrate. Comparable over-molding configurations may be employed in other embodiments of shaft seal assemblies.

In accordance with the above features, an aspect of the invention is a seal component for a shaft seal assembly. In an exemplary embodiment, the seal component includes an elastomeric element and a substrate. The seal component has an over-molded configuration in which the elastomeric element is over-molded onto the substrate.

In another exemplary embodiment of the seal component, the elastomeric element defines an over-molding recess, and the substrate includes an over-molding extension. In the over-molded configuration, the over-molding recess receives the over-molding extension.

In another exemplary embodiment of the seal component, the elastomeric material includes a pair of flexible arms that are compressible about an apex adjacent the over-molding recess.

In another exemplary embodiment of the seal component, at least one of the flexible arms defines a spring recess configured to receive a spring.

Another aspect of the invention is a shaft seal assembly. In an exemplary embodiment, the shaft seal assembly includes the described seal component with an over-molded configuration and a housing structure. The housing structure receives the seal component, and a cap structure extends over at least a portion of the housing structure. The seal component provides a seal between the cap structure and the housing structure.

In another exemplary embodiment of the shaft seal assembly, the flexible arms of the seal component are compressed about the apex toward the substrate so as to energize the seal component against an outer face of the cap structure.

In another exemplary embodiment of the shaft seal assembly, the spring of the seal component is compressed between the elastomeric element and the substrate so as to energize the seal component against an outer face of the cap structure.

Another aspect of the invention is a second seal component for a shaft seal assembly. In an exemplary embodiment, the seal component includes an elastomeric element that has a plurality of twist lock retention locking features configured to be received in a portion of a housing structure of the shaft seal assembly. When the seal component is rotated relative to the housing structure from an initial position to a second locked position, the locking features are retained within the receiving portions of the housing structure in the second locked position.

In another exemplary embodiment of the seal component, the elastomeric element has a top face, and the plurality of locking features each includes an elongated ridge that extends above the top face, wherein when the seal component is rotated relative to the housing structure from the initial position to the second locked position, the elongated ridges are compressed within the receiving portions of the housing structure in the second locked position.

In another exemplary embodiment of the seal component, the seal component has an outer diameter that includes a plurality of rib structures, wherein the rib structures provide a frictional force against an internal bore defined by the housing structure.

In another exemplary embodiment of the seal component, the seal component further includes a bottom substrate that is bonded to a bottom surface of the elastomeric component.

In another exemplary embodiment of the seal component, the substrate includes a plurality of extension portions, wherein each extension portion extends into an internal recess defined by a respective one of the plurality of locking features.

In another exemplary embodiment of the seal component, the substrate has at least one flange that extends laterally from a bottom surface of the substrate, and the flange has a contact surface configured to prevent further rotation beyond the second locked position.

Another aspect of the invention is a second shaft seal assembly. In an exemplary embodiment, the shaft seal assembly includes an elastomeric element that has a plurality of twist lock retention locking features, and a housing structure. The locking features are configured to be received in a portion of the housing structure in an initial position and second locked position, and when the seal component is rotated relative to the housing structure from the initial position to the second locked position, the locking features are retained within the receiving portions of the housing structure in the second locked position.

In another exemplary embodiment of the shaft seal assembly, the elastomeric element has a top face, and the plurality of locking features each includes an elongated ridge that extends above the top face and has a first length. The housing structure has a top face including a plurality of locking slots having a second length longer than the first length, the locking slots each being configured to receive a respective elongated ridge. When the seal component is rotated relative to the housing structure from the initial position to the second locked position, the elongated ridges move within the respective locking slots along the second length and are compressed within the locking slots of the housing structure in the second locked position.

In another exemplary embodiment of the shaft seal assembly, each elongated ridge locking feature has a first uncompressed width W1, each locking slot has a first end having a second width W2and a second end having a third width W3, and the three widths satisfy the relationship W3<W1<W2. In the initial position each elongated ridge is positioned in the first end of the respective locking slot, and when the seal component is rotated relative to the housing structure from the initial position to the second locked position, the elongated ridges move within the respective locking slots along the second length to the second ends to compress the locking slots of the housing structure in the second locked position.

In another exemplary embodiment of the shaft seal assembly, each locking feature has opposite sides that define concave recesses, and each locking slot includes ridges that are received within the concave recesses of the respective locking feature.

In another exemplary embodiment of the shaft seal assembly, the seal component has an outer diameter that includes a plurality of rib structures, and the housing structure defines an internal bore configured to receive the rib structures. The rib structures provide a frictional force against the internal bore of the housing structure.

In another exemplary embodiment of the shaft seal assembly, the seal component further comprises a bottom substrate that is bonded to a bottom surface of the elastomeric component.

In another exemplary embodiment of the shaft seal assembly, the substrate has at least one flange that extends laterally from a bottom surface of the substrate, the at least one flange having a contact surface, and the housing structure has a bottom surface that has at least one rotation recess space apart from and defined by at least one wall, and each wall ends in a blocking surface. When the seal component is rotated relative to the housing structure from the initial position to the second locked position, each flange moves within a respective rotation such that in the second locked position, the contact surface of each flange is pressed against the blocking surface of the respective wall to prevent further rotation beyond the second locked position.

Although the invention has been shown and described with respect to certain preferred embodiments, it is understood that equivalents and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalents and modifications, and is limited only by the scope of the following claims.