US20070163530A1

US20070163530A1 - Seal assembly

Info

Publication number: US20070163530A1
Application number: US11/464,556
Authority: US
Inventors: Berndt L. Luchs
Original assignee: Individual
Current assignee: Parker Hannifin Corp
Priority date: 2006-01-13
Filing date: 2006-08-15
Publication date: 2007-07-19

Abstract

A seal assembly (46) for sealing the interface between a shaft (16) and a bore-defining wall (22). The seal assembly (46) comprises a sealing element (50), a reinforcing insert (52), and an elastomeric casing (54). The sealing element (50) has a shaft-contacting portion (56) positioned adjacent the shaft (16) and an insert-engaging portion (58) positioned substantially parallel to the bore-defining wall (22). The reinforcing insert (52) has a seal-engaging portion (66) positioned substantially parallel to the bore-defining wall (22) and positioned radially outward from the insert-engaging portion (58) of the sealing element (50). The elastomeric casing (54) surrounds the radially outer sides of the engaging portions (58,66) of the sealing element (50) and the reinforcing insert (52), to thereby urge the insert-engaging portion (58) of the sealing element (50) radially inward towards the seal-engaging portion (66) of the reinforcing insert (52).

Description

RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 (e) to U.S. Provisional Patent Application No. 60/758,874 filed on Jan. 13, 2006. The entire disclosure of this provisional application is hereby incorporated by reference.

GENERAL FIELD

This invention relates generally to a seal assembly and, more particularly, to a seal assembly for sealing the interface between a shaft and a bore-defining wall of a housing.

BACKGROUND

An engine, such an automotive engine, can comprise an engine block, pistons and a crankshaft, with the pistons causing the crankshaft to rotate about an axis thereby converting linear motion into rotational motion. The crankshaft has a front end, a rear end, and a series of motion converting elements (e.g., journals, connecting arms, and crank pins) therebetween. A front seal assembly seals the interface between the front end of the crankshaft (or a component, such as a harmonic balancer, attached thereto) and a bore-defining wall in the front side of the engine block (or a front cover mounted thereon). A rear seal assembly seals the interface between the rear end of the crankshaft and a bore-defining wall in the rear side of the engine block (or a rear housing mounted thereon).

SUMMARY

A seal assembly is provided wherein chemical bonding between a sealing element and a reinforcing insert need not be depended upon to preserve the integrity of the seal structure. Instead, the relative positioning of engaging portions of the seal/insert components, and elastomeric casing positioning therearound, provides a mechanical lock between the components. This eliminates any need to be overly concerned with the chemical-bonding compatibility of the materials used for the sealing element and the reinforcing insert. The seal assembly can be used, for example, to seal the interface between the front or rear end of a crankshaft and a bore-defining wall in the engine block (or a cover/housing mounted thereon).
More particularly, a seal assembly is provided for sealing the interface between a shaft and a bore-defining wall. The seal assembly comprises a sealing element, a reinforcing insert and an elastomeric casing. The sealing element has a shaft-engaging portion positioned adjacent the shaft and an insert-engaging portion positioned substantially parallel to the bore-defining wall. The reinforcing insert has a seal-engaging portion positioned substantially parallel to the bore-defining wall and positioned radially outward from the insert-engaging portion of the sealing element. The elastomeric casing surrounds the radially outer sides of the engaging portions of the reinforcing insert and the sealing element and urges the insert-engaging portion of the sealing element radially inward towards the seal-engaging portion of the reinforcing insert.
These and other features of the seal assembly are fully described and particularly pointed out in the claims. The following description and annexed drawings set forth in detail certain illustrative embodiments, these embodiments being indicative of but a few of the various ways in which the principles of the invention may be employed.

DRAWINGS

FIG. 1 is a perspective view of the front side of an engine.

FIG. 2 is a perspective view of the rear side of the engine.

FIG. 3 is an isolated view of a front cover for the engine.

FIG. 4 is an isolated view of a rear housing for the engine.

FIG. 5 is a schematic view of the engine's crankshaft and surrounding components.

FIG. 6 is a close-up sectional view of a front seal assembly for the crankshaft.

FIG. 7 is a close-up sectional view of a rear seal assembly for the crankshaft.

DETAILED DESCRIPTION

An engine 10 can comprise an engine block 12, pistons 14, and a crankshaft 16. (FIGS. 1 and 2.) A front cover 20, with a bore-defining wall 22, is mounted to the front side of the engine block 12. (FIG. 1 and FIG. 3.) A rear housing 24, with a bore-defining wall 26, is mounted to the rear side of the engine block 12. (FIG. 2 and FIG. 4.) The pistons 14 cause the crankshaft 16 to rotate about an axis 28, thereby converting linear motion into rotational motion.
The crankshaft 16 has a front end 30, a rear end 32, and a series of motion converting elements 34 (e.g., journals, connecting arms, crank pins) therebetween. (FIG. 5.) The crankshaft 16 can include a harmonic balancer 38 forming an extension of its front end 30. (FIG. 1.) The harmonic balancer 38 can include, for example, a wheel 40 and a rearwardly projecting hub flange 42, with the flange 42 being press-fit, bolted or otherwise attached to the front end 30 of the crankshaft 16. (FIG. 5.) The wheel 40 can be part of a pulley system driving an accessory belt 44. (FIG. 1.)
A front seal assembly 46 seals the interface between the crankshaft 16 and the bore-defining wall 22 in the front cover 20. (FIG. 5.) More specifically, in the illustrated embodiment, the front seal assembly 46 seals the interface between the flange 42 of the harmonic balancer 38 and the wall 22. Before the front cover 20 is mounted to the engine block 12, the flange 42 is inserted through the bore defined by the wall 22 and the seal assembly 46 is pressed (using force directed away from the oil side of the engine and toward the air side of the engine) into the interface between the flange 42 and the wall 22.
A rear seal assembly 48 seals the interface between the crankshaft 16 and the bore-defining wall 26 in the rear housing 24. (FIG. 5.) After the housing 24 is mounted to the rear side of the engine block 12, the seal assembly 48 is pressed (using force directed toward the oil side of the engine and away from the air side of the engine) into the interface between the rear end 32 of the crankshaft 16 and the bore-defining wall 26. A flywheel (not shown), a flex plate, or another pulsation-reducing component may be attached to the crankshaft's rear end 32 after the seal assembly 48 is installed.
Referring now to FIG. 6, the front seal assembly 46 is shown in detail. As was explained briefly above, the front seal assembly 46 seals the interface between the crankshaft 16 and the bore-defining wall 22 in the front cover 20. The front seal assembly 46 generally comprises a sealing element 50, a reinforcing insert 52, and an elastomer casing 54.
The sealing element 50 comprises a shaft-engaging portion 56, an insert-engaging portion 58, and a connecting portion 60 therebetween. The portions 56, 58, and 60 form a cross-sectional horse-shoe shape, with the radially-inner portion 56 (the shaft-engaging portion) being longer than the radially inner portion 58 (the insert-engaging portion). The shaft-engaging portion 56 is positioned substantially parallel to the crankshaft 16 (or hub flange 42), the insert-engaging portion 58 is positioned substantially parallel to the bore-defining wall 22, and the connecting portion 60 is positioned substantially perpendicular to the portions 56 and 58. The sealing element 50 can open towards the oil-side of the engine block 12 (i.e., the portions 56 and 58 project rearward), as this geometry may facilitate installation of the seal assembly 46. Specifically, if the seal assembly 46 is pressed in the forward direction onto the hub flange 42 of the harmonic balancer, its connecting portion 60 (rather than the distal edges of its portions 56 and 58) will lead the way into the relatively tight seal-receiving space.
The sealing element 50 can be formed in one-piece and can be made of an appropriate shaft-contacting material. Suitable candidates include, for example, fluorocarbon polymers, (e.g., polytetrafluoroethylene-PTFE), because they exhibit relatively low friction, are chemically inert, and can withstand a variety of temperatures. Moreover, because these materials have self-lubricating properties, they can often form a coherent and compliant seal with a rotary shaft with little or no additional lubrication or sealant. In any event, the radially inner surface of the shaft-engaging portion 56 can be provided with appropriate grooves 64 for rotation, such as a triple start spiral groove. The connecting portion 60, which may also be an insert-engaging portion, can include openings or slots 62 spaced around its circumference.
The reinforcing insert 52 comprises a seal-engaging portion 66 oriented substantially parallel to the bore-defining wall 22, another seal-engaging portion 68 oriented substantially perpendicular to the portion 66, and another anchoring portion 70 also oriented substantially parallel to the bore-defining wall 22, but positioned radially outward from the portion 66. The reinforcing insert 52 can be made of metal, such as aluminum, steel, stainless steel, copper, brass, titanium, nickel, and alloys thereof. The metal may be anodized, plated, or otherwise treated for increased corrosion resistance. Ceramics or hard plastics may also be possible reinforcing materials in certain sealing situations.
The insert-engaging portion 58 of the sealing element 50 follows the profile of the seal-engaging portion 66 of the reinforcing insert 52 and is positioned radially outward therefrom. The connecting portion 60 of the sealing element 50 (which, as was indicated above, can also be an insert-engaging portion) follows the profile of the seal-engaging portion 68 of the reinforcing insert 52. In the front seal assembly 46, the seal portion 60 can be positioned on the air-side (e.g., front side) of the insert portion 68. The openings 62 in the portion 60 form a passageway through the sealing element 50 to the air-side surface of the insert portion 68.
In the illustrated embodiment, the sealing element 50 appears to be contacting the reinforcing insert 52 in the engaging portions 58/66 and 60/68, and this may very well be the case. However, in some instances, an elastomeric skin or other surface coating may be applied to the engaging surfaces. Such an elastomeric skin might form a chemical bond between the element 50 and insert 52, however these bonds are usually of limited strength and durability. In any event, as is explained below, a chemical bond between the sealing element 50 and the reinforcing insert 52 is not necessary.
The elastomeric casing 54 surrounds the radially outer surfaces of the seal-insert engaging portions 58/66 and occupies the space between these surfaces and the bore-defining wall 22. In this manner, the elastomeric casing 54 urges the insert-engaging portion 58 of the sealing element 50 radially inward towards the seal-engaging portion 66 of the reinforcing insert 52. Thus, the sealing element 50 and the reinforcing insert 52 need not depend on chemical bonding therebetween to preserve the integrity of the seal assembly 46. Instead, the relative positioning of the engaging portions 58/66 of the seal/insert components 50/52, and the elastomeric casing 54 positioning therearound, provides a mechanical lock between the components. This eliminates any need to consider the chemical-bonding compatibility of the materials used for the sealing element 50 and the reinforcing insert 52. It also removes the need to have a skin surrounding the metal insert 52 (and/or the sealing element 50) although, as indicated above, such a skin could be used.
The casing 54 can also surround the air-side surfaces of the seal-insert engaging portion 60/68, and passes through the openings 62 in the sealing element 50 to the insert portion 68. These elastomeric passages can provide a further mechanical lock, as the casing 54 bonds to the reinforcing insert 52. (A casing-insert bond will usually be much stronger and durable than an insert-seal bond.) The casing 54 can also extend into the radially inner surfaces of the sealing element 50 and the reinforcing insert 52 and/or the casing 54 can form a dirt-excluding lip 72 at the shaft-air-side edge of the seal assembly 46.
The elastomeric casing 54 can be made from a duroplastic or thermoplastic synthetic material, such as epoxy resin, bis-maleimide resin, polyurethane resin, silicone resin, PEEK, PA, PPA, PTFE, PFA, PPS, PBT, PET, PI or PAI. Natural rubber may also be an option in certain instances.
The elastomer material can be molded into the casing 54 and simultaneously around the sealing element 50 and the reinforcing insert 52 previously positioned in the mold cavity. The sealing element 50 can be provided as a flat disc (with the openings 62 formed therein) and then formed into the horseshoe shape during the molding process. The grooves 64 in the shaft-contacting surface of the sealing element 50 can also be formed prior to the molding process (e.g., machined or knifed into the appropriate location on the flat disc), or can be formed during the molding process. It may be noted that forming the grooves 64 during the molding process may provide improved production uniformity and/or accuracy. The reinforcing insert 52 can be previously formed (e.g., machined, stamped, etc.) into its desired shape prior to entering the mold cavity. If the elastomer casing 54 is to extend into the radially inner surfaces of the sealing element 50 and the reinforcing insert 52 (e.g., to form the dirt-excluding lip 72), the chaplets may be used in the mold apparatus to appropriately direct flow during the molding process.
Referring now to FIG. 7, the rear seal assembly 48, which seals the interface between the crankshaft 16 and the bore-defining wall 26, is shown in detail. Much like the front seal assembly 46, the rear seal assembly 46 generally comprises a sealing element 76, a reinforcing insert 78, and an elastomer casing 80. The rear seal assembly 48 can be made in the same or a similar manner as the front rear assembly 46, by molding the casing 80 around the sealing element 76 and the reinforcing insert 78 and forming the horseshoe shape (and grooves 90) of the sealing element 76 during this molding.
The sealing element 76 can be substantially the same as the sealing element 50, and comprise a shaft-engaging portion 82 (with grooves 90), an insert-engaging portion 84, and a connecting portion 86 (with openings 88). The horseshoe shape of the sealing element 76 opens to the air-side of the engine block 12 (i.e., the portions 82 and 84 project rearward), so that the connecting portion 86 leads when the seal assembly 48 is inserted into the space between crankshaft 16 and the bore-defining wall 26. The reinforcing insert 78, like the reinforcing insert 52, comprises a seal-engaging portion 92 oriented substantially parallel to the bore-defining wall 26, another seal-engaging portion 94 oriented substantially perpendicular to the portion 92, and an anchoring portion 96 also oriented substantially parallel to the bore-defining wall 26 but positioned radially outward from the portion 92.
The insert-engaging portion 84 of the sealing element 76 follows the profile of the seal-engaging portion 92 of the reinforcing insert 78 and is positioned radially outward therefrom. The connecting portion 86 of the sealing element 76 follows the profile of the seal-engaging portion 94 of the reinforcing insert 78. In the rear seal assembly 48, the seal portion 86 can be positioned on the oil-side (e.g., front side) of the insert portion 94. The openings 88 in the portion 86 form a passageway through the sealing element 76 to the air-side surface of the insert portion 94.
The elastomeric casing 80 surrounds the radially outer surfaces of the seal-insert engaging portions 84/92 and occupies the space between these surfaces and the bore-defining wall 26. In this manner, the elastomeric casing 80 urges the insert-engaging portion 84 of the sealing element 76 radially inward towards the seal-engaging portion 92 of the reinforcing insert 78. Thus, as in the front seal assembly 46, the rear sealing element 76 and the rear reinforcing insert 78 need not depend on chemical bonding therebetween to preserve the integrity of the seal assembly 48.
The elastomeric casing 80 can surround the oil-side surfaces of the seal-insert engaging portions 86/94 and pass through the openings 88 to provide a further mechanical lock. Additionally or alternatively, the casing 80 can also occupy regions radially inward of the reinforcing insert 78 and/or form a dirt-excluding lip 98 at the shaft-air-side edge of the seal assembly 48.
Although the seal assembly has been shown and described with respect to certain embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. It may be specifically noted that although the seal assembly 46 and the seal assembly 48 were described in conjunction with a crankshaft 16, they are certainly not limited to crankshaft applications. The seal assemblies 46/48 can be used in many situations where it is necessary (and/or desired) to seal the interface between a shaft and bore-defining wall. It is further noted that term “shaft” is meant to encompass whatever rotating component is within the bore-defining wall, and is not limited to a shaft member, per se. For example, the seal assembly 46 seals the interface between the hub flange 42 of the harmonic balancer 38 and the bore-defining wall 22.
In regard to the various functions performed by the above described elements (e.g., components, assemblies, systems, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function. In addition, while a particular feature may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.

Claims

1. A seal assembly for sealing the interface between a shaft and a bore-defining wall, said seal assembly comprising a sealing element, a reinforcing insert and an elastomeric casing;

wherein the sealing element has a shaft-contacting portion positioned adjacent the shaft and an insert-engaging portion positioned substantially parallel to the bore-defining wall;

wherein the reinforcing insert has a seal-engaging portion positioned substantially parallel to the bore-defining wall and positioned radially outward from the insert-engaging portion of the sealing element; and

wherein the elastomeric casing surrounds the radially outer sides of the engaging portions of the sealing element and the reinforcing insert and urges the insert-engaging portion of the sealing element radially inward towards the seal-engaging portion of the reinforcing insert.

2. A seal assembly as set forth in claim 1, wherein the sealing element has a second insert-engaging portion and the reinforcing insert has a second insert-engaging portions, these second engaging portions being positioned substantially perpendicular to the first engaging portions of the sealing element and the reinforcing insert, and wherein the elastomeric casing surrounds at least one of the air-side and oil-side of the second engaging portions.

3. A seal assembly as set forth in claim 2, wherein the second insert-engaging portion of the sealing element is positioned on the air-side of the second seal-engaging portion of the reinforcing insert.

4. A seal assembly as set forth in claim 2, wherein the second insert-engaging portion of the sealing element is positioned on the oil-side of the second seal-engaging portion of the reinforcing insert.

5. A seal assembly as set forth in claim 2, wherein the second insert-engaging portion of the sealing element connects its first insert-engaging portion to its shaft-engaging portion.

6. A seal assembly as set forth in claim 1, wherein the sealing element includes openings that the elastomeric casing extends through to the reinforcing insert.

7. A seal assembly as set forth in claim 2, wherein the sealing element includes openings that the elastomeric casing extends through to the reinforcing insert, and wherein the these openings are positioned on the second insert-engaging portion of the sealing element.

8. A seal assembly as set forth in claim 1, wherein the elastomeric casing forms a lip adjacent the air-side edge of the shaft-contacting portion of the sealing element.

9. A seal assembly as set forth in claim 1, wherein the reinforcing insert further comprises an anchoring portion extending from its first seal-engaging portion.

10. A seal assembly as set forth in claim 9, wherein the anchoring portion is positioned generally parallel to the bore-defining wall of the housing.

11. A seal assembly as set forth in claim 9, wherein the anchoring portion of the reinforcing element is positioned radially outward from its first seal-engaging portion.

12. A seal assembly as set forth in claim 1, wherein the sealing element is made of polytetrafluoroethylene (PTFE).

13. A seal assembly as set forth in claim 1, wherein the sealing element is made in one-piece.

14. A seal assembly as set forth in claim 1, wherein the reinforcing insert is made of metal.

15. A seal assembly as set forth in claim 1, wherein the reinforcing insert is made in one-piece.

16. A seal assembly as set forth in claim 1, wherein the sealing element is made in one piece and is made of polytetrafluoroethylene (PTFE), and wherein the reinforcing insert is made in one piece and is made of metal.

17. In combination, a crankshaft, a bore-defining wall, and the seal assembly as set forth in claim 1, wherein the seal assembly is installed on one end of the crankshaft.

18. The combination set forth in claim 17, wherein the seal assembly is installed on the front end of the seal assembly.

19. The combination set forth in claim 17, wherein the seal assembly is installed on the rear end of the seal assembly.

20. An engine comprising an engine block, pistons, a crankshaft, and a seal assembly as set forth in claim 1, wherein the seal assembly seals the interface between an end of the crankshaft and a bore-defining wall in the engine block or in a cover/housing mounted thereto.