GB2215786A

GB2215786A - Sealed machine assemblies

Info

Publication number: GB2215786A
Application number: GB8824771A
Authority: GB
Inventors: Steve A Mims
Original assignee: Chicago Rawhide Manufacturing Co Inc
Current assignee: Chicago Rawhide Manufacturing Co Inc
Priority date: 1988-03-21
Filing date: 1988-10-21
Publication date: 1989-09-27
Anticipated expiration: 2008-10-21
Also published as: SE469531B; AU2273988A; JPH01242875A; SE8804135L; FR2628813A1; IT8868075A0; IT1223960B; GB2215786B; DE3834765C2; GB8824771D0; SE8804135D0; AU615477B2; MX169810B; DE3834765A1; FR2628813B1

Description

1 215786 I/- 1 - 1 - DESCRIPTION "IMPROVEMENTS IN AND RELATING TO

ASSEMBLIES AND SEALED MACHINE ASSEMBLIES" The present invention relates generally to oil seals, and more particuarly, to a composite seal assembly adapted for specialized applications, such as sealed machine assemblies. It concerns a novel form of seal which makes possible the elimination of cumbersome, relatively unreliable former designs for certain special applications. In particular, the seal design of the present invention makes installation of rear crankshaft seals much easier and more reliable.

While the present invention has other appli cations, its primary application, that of a rear crankshaft seal, has historically presented a number of serious problems. In some engine designs the portion of the crankshaft, over which the lip of the oil seal-is required to extend, is a reduced diameter portion of the crankshaft. Accordingly, it has sometimes been customary to wrap a rope-type packing around such reduced diameter crankshaft end portion.

In other applications, the seal has been manufactured in two mating halves, and installation thereof required not only positioning one of the seal halves in a narrow recess lying within a part of the engine block above the crankshaft bearing journal, but also required precise mating of the lower half of the seal with the upper half so that there was no leakage along the surfaces at which the two half seals met in end-to-end relation.

In addition, it was often difficult to align the seal so that the seal lip would lie in a single plane to provide an effective seal. In many cases, these problems were aggrevated because the material used to form the seal lip was one which lacked mechanical strength and toughness; silicone rubbers for example, were often used in this application. This made a good seal between seal halves but the material lacked toughness and could be damaged during installation.

Another problem common not only to rear crank shaft applications but to seal installations generally, is the matter of quality control under conditions where part of the seal assembly is made by one manufacturer and the other part or parts are made by one or more other manufacturers. This situation may be aggravated where installation is done by assembly line personnel who represent a still further element in the assembly process. Modern quality assurance concepts call for placing the responsibility for an assembled element with a single person.or source, where possible. Accordingly, any arrangement wherein different elements of an assembled part are supplied from different sources or are assembled by different personnel create situations wherein it is difficult to maintain quality, and to pinpoint responsibility in the event of failure.

The present invention seeks to provid.e a seal assembly which eliminates the need to machine a counterbore in the end of the engine block. This operation May thus be eliminated.

The present invention provides 2 composite seal which ensures easy alignment and ready fastening to a flat face portion of an engine block or related part. Moreover, the invention provides a retainer element which May be Made from a synthetic plastic material at low Cost, to close tolerances, and which is susceptible of receiving and precisely locating a retainer insert which in turn carries an elastomeric seal body. The invention is particularly compatible with modern manufacturing techniques, and has a number of incidental advantages as well.

One object of the invention is to provide a composite seal assembly which includes three separate elements which are combined by the manufacturer into 2 unitary, e2sy-to-install assembly, and to provide a composite seal element whose components may be manufactured with minimum tooling expense and at low cost using high volume molding techniques.

Other objects sought to be provided by the invention are a multi-part seal whose elements may be assembled under the control of a single manufacturer; a composite seal assembly which is readily aligned and positioned relative to a fixed machine member, with a portion of the assembly encircling a relatively movable machine member and which composite seal may be reliably installed without damage in a predetermined position, of use, and a seal which readily mates in fluid tight relation with other parts, including a movable machine member and a pair of stationary machine members.

The invention is particularly applicable to a seal assembly wherein one of the elements may b.e affixed in 2 precise relation to another by ultrasonic welding techniques.

It provides a composite seal assembly wherein two of the components are made from different thermo plastic, injection molded materials, one of which is readily insert molded with and bonded to an elastomeric se2l-unit.

The invention 21SO seeks to provide a method of manufacturing an improved seal to provide a sealed mechanism which includes at least one stationary part and at least one movable machine member, and in which the fluid is confined to the interior of the sealed mechanism by a composite seal unit which includes a pair of relatively rigid plastic elements and a bonded elastomeric seal unit. The result is a multi element seal unit which is resistant to damage during installation, resistant to fatigue in use, and which will assure proper alignment and positioning relative to both fixed and movable elements. One main advantage is to provide a seal assembly which eliminates the need for performing certain finishing operations on the remainder of the seal unit.

In its preferred form, the invention provides a crankshaft seal assembly which includes a molded plastic retainer element having fastener inserts received therein and which further includes a shoulder surface arrangement for receiving and positioning 2 retainer insert which May be affixed by ultrasonic welding or the like in fluid-tight relationship to the retainer.

The insert carries a fluoroelastomer or Similar tough, high temperature resistant seal unit which directly engages a surface on a portion of the crank shaft or a similar surface to be sealed. Still further, the retainer itself includes, in addition to a mounting portion, a portion encircling the rear crankshaft extension, an outer surface adapted to be engaged in fluid-tight, static relation by the engine oil pan.

This further simplifies and improves the reliability of installation. The present invention seeks to provide these and a number of other advantages, including that of enabling an elastomeric seal unit body of small volume to be made available for this installation.

According to the present invention then, a composite seal assembly comprises a retainer element, a retainer insert, and an elastomeric sealing unit, the retainer element including an inert mounting portion which includes a radially inwardly directed annular surface defining a centre opening for receiving and radially positioning a part of the retainer insert, at least one annular shoulder surface for engaging and axially positioning another part of the retainer insert, the retainer element also having a retainer elenient mounting portion with a generally flat surface for positioning in opposed relation to an 2SSOCiated first machine part to which the retainer element will be fastened in use, and means defining plural openings for receiving and positioning retainer element mounting fasteners, the retainer insert including axially and radially extending annular flanges for cooperative engagement respectively with the radially inwardly directed annular surface and the annular shoulder surface of said retainer element, the retainer insert further including an annular bonding portion, the elastomeric sealing unit including a bonding portion and a generally annular seal body which includes generally frustoconical oil and air side sealing element surfaces meeting each other along -a generally circular locus to form a primary seal band are2 Of intended contact with the surface of a relatively movable second macnine part extending axially through the seal body, said bonding portion being attached in fluid tight sealing engagement to the bonding portion on the retainer insert, the retainer element and the retainer insert each being formed from a resinous synthetic plastic material, with the seal assembly being adapted to be affixed in use to the end face of a first machine part having the relatively movable second machine part extending therefrom and adapted to be engaged by the elastomeric sealing uni I-.

Also according to the present invention, a composite seal assembly for retaining fluid within a cavity, formed at least in part by first, second and third relatively movable machine parts, comprises in combination, a retainer element having a mounting portion adapted to be affixed to the first machine part and another portion adapted to be positioned so as to encircle the rotational axis of the second machine part, a retainer insert having a bonding portion and being positioned at least partially within and carried by the portion of the retainer element which encircles the second part axis, and a unitary elastomeric sealing unit having a generally annular seal body portion with generally frusto conical oil and air side sealing element surfaces meeting each other along a generally circular locus to form a primary seal band area of intended contact with a surface on the second machine part, the sealing unit also having an annular bonding portion spaced apart from the seal band area and having at least one of its surfaces secured in fluid-tight relation to the retainer insert, the retainer element and the retainer insert being made from relatively rigid, substantially fluid-impermeable synthetic plastics materials, the mounting portion of the retainer element also including an end face surface adapted to be positioned in fluid-tight Mating relation with a counterpart-mounting surface on the first machine part, and the other portion of the retainer element having a radially outwardly directed static sealing surface formed on a portion of its exterior so as to be engageable with the third machine part in fluid tight relation, the mounting portion of the retainer element further including a plurality of openings for removably receiving a plurality of mounting fasteners to facilitate positioning of the assembly relative to the first machine part.

Furthermore, according to the present invention, a method of making a composite seal assembly includes the steps of molding a retainer insert having an insert body with axially and radially extending annular flanges thereon from a thermcplastic material, treating at least a part of the surface of one of the radially extending flanges to impart a roughened texture thereto, positioning the insert in relation to a sealforming mold such that the flange with the roughened texture surface lies within the cavity of the mold, forming 2 generally annular seal body which includes generally frusto-conical air and oil side sealing element surfaces meeting each other along a generally circular locus to form a primary seal band area of intended contact with the surface of an associated movable machine part from a curable fluent elastomeric Material, and permitting that material to cure and a portion thereof to bond to the roughened texture surface portion of the retainer insert radial flanqe, forming a retainer element from a synthetic plastic material, which retainer element includes an insert mounting portion having 2 radially inwardly directed annular surface defining a centre opening for receiving and radially positioning a part of the retainer insert, the retainer element also including at least one annular shoulder surface for engaging and axially positioning another part of the retainer insert, with the retainer element also having a retainer element mounting portion with a generally flat surface for positioning in opposed relation to an associated machine part to which the retainer element will be fastened in use, providing means in the retainer element for receiving and positioning retainer element mounting fasteners, disposing the retainer insert at least partially within the centre opening such that the radially inwardly directed annular surface and the annular shoulder surface on the rptainer element engage portions of the retainer insert body, and bonding the retainer element and the retainer insert to each other in fluid-tight sealing engagement.

The invention will now be further described by way of examples with reference to the accompanying drawings, in which like reference numbers indicate corresponding parts throughout. In the drawings:- Fig. I is a perspective view of the composite seal of the invention, showing it in a position of use as a rear crankshaft seal, an associated engine crankcase and crankcase oil pan being indicated in phantom lines; Fig. 2 is a fragmentary vertical sectional view of a portion of the composite oil seal unit of the invention, showing the same in position of use and showing the fixed and movable machine elements relative to which it is intended to form a seal; Fig. 3 is a view showing the elements of Fig. 2 in their exploded or pre-assembled relation; Fig. 4 is a vertical sectional view, partly diagrammatic in nature, showing the manufacture of the retainer insert and the elastomeric sealing units of the invention; Fig. 5 is a side elevational view of the seal assembly of the invention, showing it in association with other portions of the sealed mechanism; Fig. 6 is a perspective view of a modified form of composite seal unit of the invention; and Fig. 7 is a side elevational view of the composite seal of the invention and the installed position of use.

While the assembly of the invention is capable of use in a number of environments, and is adapted for a number of applications, a detailed description of two different forms of seal of the invention will be given. which versions differ slightly from each other and both of which are intended for use as a rear crankshaft seal assembly in an automotive engine application.

Referring now to the drawings in greater detail, Fig. 1 is a perspective view of a composite seal assembly generally designated 10 and shown to be positioned near a mounting surface 12 forming a part of a first machine element 14, with which it is intended to be associated in use.

The composite seal assembly 10 includes three principal elements, which are shown in Figs. I - 3; these include a retainer element generally designated 16, a retainer insert generally designated 18, and an elastomeric sealing unit generally designated 20. In the application considered, the first machine element 14 is an automotive engine block, the mounting surface 12 thereof forming the rear end face surface of the block.

A rear crankshaft extension 22 (Fig. 2) forms a second machine element and the extension 22-protrudes through a center opening generally designated 24 in the seal assembly 10. An engine oil pan generally designated 26 forms the third machine element; the pan 26 is shown in phantom lines to have surface portions 28 which engage a partially cylindrical lower exterior surface 30 of the retainer element 16.

The crankshaft or crank extension 22 has a cylindrical exterior wear surface 32 over which a portion of the elastomeric seal unit 20 rides in fluid tight relation. The seal unit 20 itself is of generally conventional construction insofar as it includes an elastomeric seal body 34 having air and oil side, generally frusto-conical surface portions 36, 38 which meet along a generally circular locus to form a seal band 40; this is the portion that engages the surface 32 with what is termed a dynamic seal, i.e., a seal between relatively movable elements.

The seal body 34 may optionally include an excluder or dirt lip 42, also of a conventional construction known to those skilled in the art. A garter spring 44 is shown to be received in a groove 46 (Fig. 3) for imposing a radial compressive load on the seal lip or band 40. The seal body 34 also includes a pair of bonding surfaces 48, 50 of annular form, spaced from the seal band 40, and along which the seal body 34 is attached to the retainer insert 18.

The insert unit 18 itself is also of generally annular form and includes a body portion 52 with an axially extending flange 54, a radially inwardly extending 2 seal body mounting flange 56 and a radially outwardly extending locating flange 58. The axial flange 54 and the radially outwardly extending flange 58 respectively include surfaces 60,.62 which are adapted to engage oppositely directed counterpart surfaces on the retainer element 16 in a mechanically secure, fluid-tight relation. As is discussed in greater detail below, the annular retainer insert 18 is preferably made from a synthetic plastic material.

Referring now to the retainer element 16, this unit includes a main body portion 64 also preferably made from a thermoplastic material; the element 16 may be considered from a functional shank part as having a mounting portion generall designated 66, and an insert receiving portion y 68. The body 64 includes an axial flange 70 having a radially inwardly directed cylindrical surface 72 for engaging the surface 60 of the insert flange 54 and an end face or shoulder surface 74 is provided on the flange 70 for engaging the surface 62 on the insert radial flange 58. In use, these abutting pairs of surfaces form fluid-tight joints in the assembled condition of the seal assembly 10.

The body 64 of the retainer 16 further includes a radially inwardly extending protective flange 76, which terminates in three or more individual tabs or ears 78.

13n This fl--gc '46s ax2a"y inwardly of the seal unit IL U - 1 1 f Li -L L L -L L 20, i.e., toward the sealed region or to the riqht in Fig.s 2 and 3.

Referring now to the mounting portion 66 of the composite seal unit 10, this portion is shown to include a mounting body 80 ha%ing a flat end face surface 82 adapted to 2but the crankcase end face surface 14.

a -15A gasket "G" (Fig. 3) may be provided for improved sealing in this area. The retainer body 80 also includes a plurality of spaced apart formed fastener bosses 83, each having an axially extending opening 84,all located above the mide line of the centre opening of retainer element 16.

The openings 84 receive metal insert sleeve 86 in snug relation; the preferred form of insert sleeve 86 includes a radial flange 88 thereon for engaging the undersurface 90 of the cap screw fastener 92 which extends through the central opening in the insert sleeve 86. In this manner, the fasteners 92 'bottom ouC on the metal insert sleeve 86 which extends between the end face surface 14 of the engine block 12 and the undersurface 90 of the fastener head.

As shown in Fig. 1, the mounting portion 80 preferably includes a peripheral stiffening wall generally. designated 54 and subdivided into an upper wall unit 95. a pair of lateral stub walls 97, and a semicircular lower wall 99. A plurality of individual stiffening webs 96,_ extend between the upper wall unit 95 and the flange 70 as well as between parts of the bosses 83 and flange 70 or wall 95. The stub walls 97 form parts respectively of left and right hand transverse mounting body extensions generally designated 98, 100# each of which is shown in Fig. 1 to be provided with a vertically extending passage 102F 104. The passages receive fasteners extending respectively through the openings 106,, 108 in the-oil pan 26.

In this connection, and referring again to Fig. 1, it will be realized that once the retainer unit 16 is snugly bolted to the crankcase, the oil pan may then be affixed not only to the underside surfaces of the crankcase in a conventional manner but that other fasteners may extend through the pairs of openings 106, 102; 104, 108, to secure the parts in fixed relation. In this instance, captive nuts or other fasteners may be provided for the passages 102, 104, or tapped inserts may be used, as indicated.

Fig. I also shows that a plurality of webs 112 extend between the lower surfaces of the retainer axial flange 70 and the semicircular lower wall 99 of the retainer element 16. These webs, walls and bosses provide a stiff construction at minimum weight and are consistent with ? n higb volume manufacture usinq relatively simple molds.

Referring now to Fig. 5, the composite seal 10 is shown in the installed position. Here, a fastener 92 is shown extending through the fastener boss 83 so that the end faces 14, 82 of the crankcase and retainer element respectively are shown in abutting relation. For clarity of illustration, the gasket OV is not shown. Fig. 5 shows one of a pair of vertically extending fasteners 110 which hold the oil pan 26 to the stub walls 97 of the retainer unit 18.

Referring now to Fig. 6, a slightly modified form of seal assembly 10A is shown. The assembly is the same as that shown in Figs. 1-3 except that the retainer element generally designated 16A in Fig. 6 differs slightly from the retainer element 16 in Fig. 1. In the form shown in Fig. 6, the upper wall unit 95A is continuous and lies entirely radially outside the various fastener bosses 83A.

Additional stiffening webs 96A extend between pairs of lateral stub walls 97A and the semicircular lower wall 99A includes rounded transition sections 101A at its upper ends rather than having upper ends which abut the stub walls at right angles. No auxiliary or vertical fasteners or openings therefore are required to affix the oil pan 26A. In this connection, it will be noted that the mating surface 28A of the oil pan 26A is contoured so as to having flaring transition sections 27A to mate with counterpart sections 101A on the outer ends of the lower exterior wall 99A. In the embodiment shown, a groove 29A is provided in the oil pan mating surface 28A to receive a gasket 31A to seal the interface between the surfaces 28A and 30A.

Fig. 7 shows the seal assembly 10A in the installed position of use, showing the relation of the engine block 12A, the abutting surfaces 14A, 82A on the engine block or first machine member 12A, the retainer unit 16A and the gasket "G.0 Fasteners 92A are shown in phantom lines.

The engine oil pan 26A and its flange 28A.which engages the lower exterior surface 30A of the lower wall 99A of the retainer unit 16A, are illustratedt as is the axial flange 70A of the retainer element 16A, and the radial flange 58A of the insert 18A, for example.

Referring now to Fig. 4, there is shown one step in the operation of manufacturing the composite seal which precedes the assembly step shown in Fig. 3. Beret in Fig.

4, the retainer insert 18 is shown disposed within a mold generally designated 200 and shown to include three principal elements, a lower mold plate 202F a center core 204, and an upper insert 206. In this form of the invention, the retainer insert 18 is formed from a plastic material by injection molding in a mold with a suitably shaped cavity so as to provide the body 52 with the axial flange 54, the seal body mounting flange 56, and the locating flange 58.

After formation of the insert 18, the exterior surfaces of the flange 56 are degreased and grit blasted so as to impart a slightly roughened finish thereto. In the alternative, surface roughness may be imparted by chemical etching or by providing rough surfaces on selected portions of the mold interior. In any case, after surface preparation is complete, an adhesive of a type known to those skilled in the art is applied and allowed to dry. Thereafter, the retainer insert body 52 is placed in the mold 200 as illustrated, and rubber may be injected, as through passage 208, into the cavity formed by the inwardly directed surfaces of the mold parts 202, 2041 206. The in-place formation of the seal body 34, its initial curing and bonding to the radial flange 56 are carried out in a manner known to those skilled in the art and which, forming no part of the invention which is novel per se, is not herein described in further detail.

Assuming that the seal bod is made from a 1- y fluoroelastomer material, after the mold shown in Fig. 4 is opened, and the part removed, the composite part comprising the elastomeric seal body 20 and the retainer insert 18 is post cured at an elevated temperature, such as 4000F. (2040C), for 10 -hours. This produces a completed, cured subassemblY shown in Fig. 3.

Referring now to Fig. 3, there is illustrated the alignment and positioning of the retainer element 16 and the retainer insert 1B. When these parts are aligned as shown in Fig. 3 and then moved into an assembled relation, the various illustrated mating pairs of surfaces 60, 72, and 62, 74 are in snug engagementr thereby centering the insert relative to the retainer 16 and insuring the proper axial positioning of the insert 18. Thereupon, the parts may be bonded by well-known ultrasonic welding techniquest with or without the aid of auxiliary adhesives or similar materials. In appropriate cases, the bonding may be, achieved by adhesives only.

When molding and assembly operations have been completed, a seal of the kind illustrated in Fig. 2, for example, has been produced and is suitable for shipment to the manufacturer.

As pointed out above, the installation of the seal is then a matter which requires relatively little skill and no post finishing or machining on the machine parts in question, that ist the engine block, crankcase oil pan or the like. The retainer may be positioned as shown in Fig.

1, with the gasket "G' disposed between the face 14 on the engine block and the front or axially inner surface 82 on the retainer unit 16.

1 n on e emalbodirtnient of the invention, the gasket "Gj, 0 - while manufactured separately, may be bonded to the retainer surface at the seal making factory, and the gasket may then have its other surface covered protectively by a release paper "R,, I for example, (Fig. 3) for shipping. The outer, covered face may or may not also 1 have a self-adhesive material affixed thereto. In such casei only surface preparation of the block is necessary# because the seal includes its own gasket and gasket adhesive.

The alignment and fastening of cap screws 92 or the like insures proper alignment of the seal with the rear crankshaft extensionj while the tab units 78 on the protective flange 76 insure that the radial excursion of the elastomeric seal unit 20 is limited and thus not damaged during installation. The plastic exterior surface 30 of the lower wall 99 mates in fluid-tight relation with the surface 28 on the oil pan 26, customarily sealed by a part of the oil pan gasket.

Because of the overall rigidity of the retainer 16, relatively high static sealing forces may be applied to the assembly 10 without detrimental affect; if this force were placed on the exterior casing of an ordinary oil seal, distortion of the seal casing or other installation fault might result. The installation of the seal, according to the present inventiont is greatly simplified, and greatly increased reliability is achieved.

According to the invention, thermoplastic materials are preferred for use in making the retainer and insert components of the invention. Both these elements may be made from the same material, or the two can comprise dissimilar materials. While many different materials are suitable, filled thermoplastic resins such as glass-filled nylon or other polyamide resins are suitable. High temperature resistant thermoplastics such as polycarbonates,, acetals or other materials may also be used with success.

While ordinary elbstomers such as nitrilest carboxylated nitriles, or silicone elastomers may be used in making the seal unit 20r the present invention advantageously uses fluoroelastomer materials which are very high temperature resistant. Accordingly, in use, the seal is effective where fluid temperatures attain a steady 2500F. (121OC) and occasionally reach temperatures of 4001F. to 500OF (2040C to 260OC).

The use of the ultrasonic welding techniques is an economical way to form a strong secondary or static seal between the retainer and the insert.This eliminates a potential prior art problem of a faulty secondary sealt i.e., the seal between the exterior of the seal casing and the main h&z.>rinn web or part of the crankcase structure. Another important feature of the present invention is that proper alignment may be achieved without press fitting. Use of a bolt pattern on an exterior flat surface not only eliminates the likelihood of this misalignment, but permits a visual inspection to be made to verify proper fit; this was difficult or impossible I with some prior art seals.

It will thus be seen that the present invention provides a number of advantages and characteristics including those pointed out above and others which are 'inherent in the invention. Preferred embodiments of the invention having been described by way of example, it will occur to those skilled in the art that variations in the exact form of seal and the materials used therein may be made without departing from the scope of the appended claims.

.

Claims

-24CLAIMS

1. A composite seal assembly comprising a i retainer element, a retainer insert, and an elastomeric sealing unit, the retainer element including an insert mounting portion which includes a radially inwardly directed annular surface defining 2 centre opening for receiving and radially positioning a part of the retainer insert, at least one annular shoulder surface for engaging and axially positioning another part of the retainer insert, the retainer element also having a retainer element mounting portion with a generally flat surface for positioning in opposed relation to an associated first machine part to which the retainer element will be fastened in use, and means defining plural openings for receiving and positioning retainer element mounting fasteners, the retaineT insert including axially and radially extending annular flanges for cooperative engagement respectively with the radially inwardly directed annular surface and the houlder surface of sald retainer element, U I I the retainer insert further including an annular bonding portion, the elastomeric sealing unit including a bonding portion and a generally annular seal body which includes generally frustoconical oil and air side sealing element surfaces meeting each other along a a generally circular locus to form a primary seal band area of intended contact with the surface of a relatively movable second machine part extending axially through the seal body, said bonding portion being attached in fluid tight sealing engagement to the bonding portion on the retainer insert, the retainer element and the retainer insert each being formed from a resinous synthetic plastic material, with the seal assembly being adapted to be affixed in use to the end face Of 2 first machine part having the relatively movable second machine part extending therefrom and 2d2pted to be engaged by the elastomeric se2ling unit.

2. A composite seal assembly for retaining fluid within a cavity, formed at least in part by first, second, and third relatively movable machine parts, comprising, in combination, a retainer element having a mounting portion adapted to be affixed to the first machine part and another portion adapted to be positioned so as to encircle the rotational axis of the second machine part, a retainer insert having a bonding portion and being positioned at least partially within and carried by the portion of the retainer element which encircles the second part axis, and a unitary elastomeric sealing unit having a -26generally annular seal body portion with generally frusto-conical oil and air side sealing element surfaces meeting each other along a generally circular locus to form a primary seal band area of intended contact with a surface on the second machine part, the sealing unit also having an annular bonding portion spaced apart from the seal band area and having at least one of its surfaces secured in fluid-tight relation to the retainer insert, the retainer element and the retainer insert being made from relatively rigid, substantially fluid-impermeable synthetic plastics materials, the mounting portion of the retainer element also including an end face surface adapted to be positioned in fluid-tight mating relation with a counterpart mounting surface on the first machine part, and the other portion of the retainer element having a radially outwardly directed static sealing surface formed on a portion of its exterior so as to be engageable with the third imachine parL in fluid-tight relation, the mounting portion of the retainer element further including a plurality of openings for removably receiving 2 plurality of mounting fasteners to facilitate positioning of the assembly relative to the first machine part.

3. A composite seal assembly as claimed in claim 1 or 2 wherein the mounting portion of the retainer element includes a plurality of metal guide insert sleeves received respectively within the openings for said mounting fasteners, the metal insert sleeves being sized so as to engage the fasteners and absorb at least a portion of the axial fastening load, whereby the load is not transmitted entirely to the mounting portion of the retainer element.

4. A composite seal assembly as claimed in claim 1, 2 or 3 wherein the bonding portion of the retainer insert comprises an annular, generally radially inwardly extending flange.

5. A composite seal assembly as claimed in claim 1, 2, 3 or 4 wherein the retainer element and the retainer insert are made from different thermoplastic materials.

6. A composite seal assembly as claimed in 1, 2,3 or 4 wherein the retainer element and the retainer insert are made from substantially identical plastic materials.

7. A composite seal assembly as claimed in any one of claims 1 to 6 wherein the retainer element mounting portion is constructed 2nd arranged such that j -28the openings for the mounting fasteners lie above the rrid line of the centre opening in the retainer i i element.

i i

S. A composite seal assembly as claimed in I any one of claims 1 to 7 wherein the retainer insert is affixed to the retainer element by a bond formed by ultrasonic welding.

9. A composite seal assembly as claimed in any one of claims 1 to 8 wherein the elastomeric sealing unit is made from a fluoroelastomer material.

10. A composite se2l assembly as claimed in claim 1 or any claim appendant thereto wherein the retainer element further includes a generally radially inwardly extending flange positioned axially inwardly of the radially inwardly directed annular surface and the annular shoulder surface on the insert mounting portion of the retainer element.

11 A composite seal assenbl as claimed in claim in wherein the radially extending flange includes a plurality of radially inwardly extending tabs or ears circum.ferentially spaced apart from each other, these tabs or ears being adapted for engaging the relatively movable machine part, adapted to extend through the seal assembly, for positioning the same for installation.

12. A sealed machine assembly comprising, in combination, first and third machine parts, a second machine part Movable relatively to the first and second machine parts, and a composite seal assembly as claimed in any one of claims 1to 11 for retaining fluid within a cavity formed at least in part by the first, second, and third machine parts.

13. A sealed machine assembly as claimed in claim 12 wherein the retainer element is affixed to the first machine part by removable fasteners and wherein the mounting portion of the retainer element further includes means for removably receiving a plurality of the fasteners to facilitate positioning of the composite seal assembly relative to the first machine part.

14. A method of making a composite seal assembly, including the steps of molding a retainer insert having an insert body with axially and radially extending annular flanges thereon from a thermoplastic material, treating at least a part of the surface of one of the radially extending flanges to impart a roughened texture thereto, positioning the insert in relation to a seal-forming mold such that the flange with the roughened texture surface lies within the cavity of the mold, forming a generally annular seal body which includes generally frustoconical air and oil side sealing element surfaces meeting each other along a generally circular locus to form a primary seal band area of intended contact with the surface of an associated MOV2ble machine part from a curable fluent elastomeric material, and permitting that material to cure and a portion thereof to bond to the roughened texture surface portion of the retainer insert radial flange, forming a retainer element from a synthetic plastic material, which retainer element includes an insert mounting portion having a radially inwardly directed annular surface defining a centre opening for receiving and radially positioning a part of the retainer insert, the retainer element also including at least one annular shoulder surface for engaging and aXi2llV positioning another part of the retainer insert, with the retainer element also having a retainer element mounting portion with 2 generally flat surface for positioning in opposed relation to an associated machine part to which the retainer element will be fastened in use, providing means in the retainer element for receiving and positioning retainer element mounting fasteners, disposing the retainer insert at least partially within the centre opening such that the radially inwardly directed annular surface and the annular shoulder surface on the retainer element engage portions of the retainer insert body, and bonding the retainer element and the retainer insert to each other in fluid-tight sealing engagement.

-31

15. A method as claimed in claim 14 wherein the bonding comprises ultrasonically welding the retainer element to the retainer insert without the use of adhesives.

16. A method as claimed in claim 14 wherein the bonding step is a step which includes applying an adhesive to selected surfaces of at least one of the retainer element and the retainer insert.

17. Composite seal assemblies substantially as herein described with reference to and as illustrated in the accompanying drawings.

18. A sealed machine assembly substantially as herein described with reference to and as illustrated in the accompanying drawings.

19. A method of making a composite seal assembly substantially as herein described with reference to the accompanying drawings.

polished 1989 &tThe patent office, State House, 66,71 High Holborn, londonWC1R4TP, Further copies maybe obtained from The P&teut=cc.