UNITIZED DUAL-LIP SHAFT SEAL

Abstract: A unitized grease seal (10). The seal member has a one-piece metal case (15), a molded elastomeric member (16) bonded to the metal case (15) and providing a series of spaced-apart inwardly extending retaining portions (38). The elastomeric member (16) also has two diverging lip portions (40-41) with a cavity (44) between them, one providing a grease retention lip (40) having small spaced-apart shallow indentations (43) enabling passage of small amounts of grease into the cavity (44), the other lip (41) portion having a polytetrafluoroethylene insert (17) bonded thereto. A one-piece metal wear sleeve member (12) has a shaft-engaging cylindrical portion (52) engaged by the lips (40-41) and a radially outwardly extending flange (57) with an axially inturned portion (58) having an outer portion (59) spaced radially inwardly from the outer generally cylindrical portion of the elastomeric member (16) but extending radially outwardly beyond the radially inner extremities of the retaining portions (38). During assembly, the wear sleeve flange's inturned portion (58) is snapped into the space between the retaining portions (38) and the case's radial flange (30).

Description: -t Unitized dual-lip shaft_seal 2 3 4 This invention relates to an improved dual-lip 5 _. grease-retaining and dirt-excluding shaft seal, o 7 Background of the Invention 8 With customers demanding ever increasing quality 9 and long life, automobile manufacturers have, in turn 10 demanded more from the manufacturers of shaft seals. Some 11 seals of the present invention are intended to be used on 12 wheel spindles of automobiles, and to last without 13 replacement for as long as 100,000 miles, while retaining 1 the grease and excluding grit, dirt, corroding liquids, 15 and so on. The seals heretofore made have not had so long 16 a life. Moreover, the seal is required to be installable 17 in a very small space. 18 Exclusion of deleterious foreign matter is even 19 more important than the retention of the grease, as in 20 certain applications grease may be added to the wheel 21 bearings from time to time; in fact, it is desirable to 22 have some grease flow out from the grease retaining seal 23 lip into the space between the grease-retaining lip and 24 the dirt-excluding lip, so as to lubricate both lips. It 25 26 is not even harmful to have a small amount of grease 2 7 expelled via the dirt-excluding lip during lubrication of 28 the wheel bearings. However, the amount allowed to pass 29 the grease-retaining lip should be kept very small. 30 In any event, there tends to be more wear at the 3_ dirt-excluding lip; because that lip is quite likely to 32 come into contact with dirt, grit, dust and corroding -~ liquids. It is also desirable to fling the outside foreign 34 matter outwardly in such a way that it tends not to work 35 its way to the dirt-excluding lip, but even with such 6 7 flinging, there will still be a substantial amount of deleterious foreign matter attempting to pass by the lip over a period of driving an automobile 100,000 miles. U.S. Patents Nos. 4,399,998 and 4,344,631 show some venting structure for seal lips, as does U.S. Patent 2,830,832, but none of these vents are suitable for use in the present seal. It is also important that the seal be unitized, because with a precision product of this kind and of this size, wrong or careless installation can immediately ruin the sealing lips and lead to the manufacturer's having to make good his guarantee on the wheel bearings. Assembly- line workers in automobile plants are often careless, and even though they may try to be careful, separate installa- tion of a seal and then of a dirt flinging member or of a wear sleeve to go upon the shaft tends to produce mis- alignments which considerably shorten the life of the seal, and may in fact cause its ruin within a few miles of the running of the new car. There are many unitized seal structures, including those shown in U.S. Patents Nos. 3,021,161; 3,108,815 3,179,424; 3,685,841; 3,561,770; 4,028,057; and 4,285,526, but few, if any, are applicable to a seal as narrow as that of the present invention. Some of the enumerated patents show dual-lip seals, but none like those of the present invention. To insure long life at the dirt exclusion seal, a very long lasting seal composition is desirable . It is possible to make a seal having many of the features of the present invention by using only a standard high quality elastomer such as acrylic rubber , butyl rubber , or an ethylene acrylic rubber (e.g . , Vamac ® , a DuPont® Reg . Trademark) . However , the use of polytetrafluoroethylene, or an equivalent material, at the actual sealing edges is highly desirable. The incorporation of polytetrafluoro- ethylene becomes important due to the fact that the temperature of the seal during use may rise to between 300 and 350°F . Also the pressure from the grease side of the seal may rise to the range of 50 to 60 p. s. i . at up to about 1200 rpm, which corresponds to vehicle speeds of 80 to 90 miles per hour . Polytetrafluoroethylene also reduces the torque of the seal on the wear sleeve. since polytetrafluoroethylene cannot be read ily and economically molded to complex shapes, it usually must be incorporated into the seal by using a wafer-like washer , as by bonding it to an elastomer ic suppor ting member. The present invention does this in novel manner employing a novel method of manufacture to produce a novel product. The method further , includes features in addition to the incorpor ation of the polytetraf luoro- ethylene. Polytetrafluoroethylene is shown bonded to elasto- mers in shaft seals in many patents , including U . S . patents Nos . 3 , 495 , 843 and 4 , 239 , 243 and East German Patent No. 328 , 815 , but, again the structure of the present invention and the method of producing it do not appear to be known. Summary of the Invention The product of this invention is a unitized grease seal and compr ises a dual-lip seal member and a wear- sleeve member attached together , preferably releasably. The seal member comprises a one-piece metal case , a molded elastomer ic member bonded to the metal case, and a polytetrafluoroethylene lip member bonded to the elasto- mer ic member and providing the dirt-excluding sealing lip. The case has a cylindrical outer portion defining a wall with an outer surface adapted to be press fitted into a stationary bore. If desired, part of the outer surface may be covered with elastomer , and this elastomer nay be a por tion of the elastomer ic member . A reverse cylindrical portion extends back from one end of the outer wall and has an outer sur face bearing against the inner surface of that wall . The reverse portion is much shorter than the outer portion, and from its inner end, a radial flange extends inwardly to a radially inner end. The flange has an outer face on the air side of the seal, continuous with the inner face of the reverse portion. The molded elastomeric member is bonded to the metal case. Thus, a radially extending portion of the elastomeric member is bonded to the outer face of the radial flange, and an outer generally cylindrical portion is bonded to the inner surface of the reverse portion. This generally elastomeric cylindrical outer portion has a series of radially inwardly extending wear-sleeve- retaining portions spaced circumferentially from each other. An inner portion of the elastomeric member extends inwardly of the radially inner end of the case's radial flange, being bonded thereto, and has two diverging lip portions, meeting, as molded, at about 90° at a point spaced radially in from the inner end of the case, and there is a cavity in between these lip portions. One of these lip portions is on the grease side of the seal, and it has a grease-retention lip provided with a series of spaced-apart small relieved indentations enabling passage of small amounts of grease into the cavity. The other lip portion provides a dirt-excluding lip portion. Preferably, it has a cylindrically extending recess therein, and a polytetrafluoroethylene sealing lip member fits into the recess and is bonded to the elastomeric member. This poly- tetrafluoroethylene lip preferably provides the sealing edge portion of that lip portion. In addition to the seal member, there is a one- piece metal wear sleeve and deflector member having a radially inner, cylindrical, wear sleeve portion with an inner surface adapted to be press fitted on a rotatable sha t and an outer surface engaged by both of the sealing lips. The outer diameter of this cylindrical portion is greater than that of the as-made inner diameter of the sealing lips, so that assembly of the wear sleeve on the seal member causes further spreading-apart of the two lips. The dirt-excluding lip, when in position on the wear sleeve, has an end wall on its air side that is substan- tially perpendicular to the wear sleeve's outer surface, or as nearly perpendicular as is practical. The wear sleeve member also has a unitizing radially outwardly extending flange portion serving as a deflector and slinger to protect the dirt-excluding lip from much of the foreign matter that otherwise come into contact .with that lip. It also helps to unitize the assembly. Preferably it first extends radially outwardly from the air-side end of the wear sleeve's cylindrical portion and then turns in toward the radial flange of the case. Near or at its outer end, a portion is spaced inwardly from the outer, generally cylindrical portion of the elastomeric member but extends outwardly beyond the radially inner extremities of the elastomeric retaining portions, so that this deflector portion of the wear sleeve member can be snapped into the space between the elastomeric retaining portions and the elastomer-coated radial flange of the metal case. The invention also includes a method for making the unitized dual-lip shaft seal. It may begin by seating on a first mold member the one-piece metal case, its outer bore-engaging cylindrical portion being seated against a second mold member, appro- priate parts of the case being covered with elastomer- bonding cement. A third mold member is engaged with the first mold member so as to define between them a cavity for molding to finished size and shape the grease-facing lip, at an angle of about 45° to the radial flange. The third mold member is also shaped to provide a series of projections in the cavity that provide the spaced-apart indentations in the grease-retaining lip. This third mold member also provides one surface of the cavity for the dirt-excluding lip, this surface sloping in the opposite direction from the grease-lip cavity, at an angle of about 45° to the radial flange, so that the two cavities 1 meet at about 90°. The sloping surface leads to a ledge 2 spaced away from the radial flange and parallel to the 3 plane thereof; the ledge ends at an inner cylindrical 4 boundary. 5 A flat washer of polytetrafluoroethylene is placed 6 on the ledge with the inner circumference of the washer 7 engaging the boundary and the outer circumference extend- 8 ing beyond the ledge and overhanging a portion only of the 9 sloping surface. Appropriate surface portions of the 0 washer are treated beforehand, as by acid etching and then 1 with bonding cement, to enhance the bonding of elastomer 2 thereto. 3 A ring of uncured elastomer ("prep") is placed on 4 top of the portion of the polytetrafluoroethylene washer 5 supported by the ledge, and a fourth mold member is 6 brought toward and against the second and third mold 7 members to close the mold, all of the mold members being 8 heated to a molding and curing temperature. Closing the 9 mold defines the remainder of the mold cavity for the 0 dirt-excluding lip and defines a further cavity for the 1 radial portion next to said radial flange and the outer 2 cylindrical portion of the elastomeric member. This outer 3 cylindrical portion of the mold is shaped to provide a set 4 of circumferentially spaced apart cavity portions extend- 5 ing radially inwardly to provide the wear-sleeve retention 6 members. The movement of the fourth mold member simulta- 7 neously forces the elastomer to flow into all the mold 8 cavities and also to flex the overhanging portion of the 9 polytetrafluoroethylene washer into engagement with the 0 sloping mold surface and to initiate bonding of the 1 elastomer to the case and to the washer. 2 The elastomer is then cured under heat and 3 pressure to a desired cure, so that it holds its shape and 4 completes the bonding of the elastomer to the case and the 5 washer. Thereby, it produces the shaft sealing member, 6 which has a grease-retaining lip molded to its final shape 7 and a dirt-excluding lip, which at that time has a portion ■ M. extending generally inwardly therefrom; the shaft sealing member also has its molded set of wear-sleeve retention members spaced away f rom the case ' s radial flange. The mold is then opened and the shaft sealing member removed. Next , the dirt-excluding lip is tr immed to a desired length, the edge being trimmed at a desired angle so that when the seal is unitized and the lips are spread apart, the tr immed edge is nearly parallel to the case ' s radial flange. In addition , a one-piece metal wear sleeve is formed with a cylindrical portion for engagement with both sealing lips and of a diameter to spread apart those lips and, as a result, to move the tr immed edge to its afore- mentioned near ly-parallel position. The wear sleeve also has a shaped radially outwardly extending deflecting portion, of a size enabling unitization. Then, the wear sleeve and shaft sealing member are assembled together . The sleeve ' s radially outwardly extending portion is placed on the air side of the shaft sealing member , and the lips are placed in engagement with the cylindrical portion of the wear sleeve . The radially outwardly extending portion is then snapped into the space between the elastomer ic retention members and the elastomer-covered radial flange , so that the retention members thereafter hinder retraction of the wear sleeve f rom the shaf t-sealing member , although it can , if desired, be taken off . Brief Description of the Drawings Fig . 1 is a view in end elevation of a unitized dual- lip shaft seal embodying the pr inciples of the invention. Fig. 2 is a greatly enlarged view in section of one portion of the seal taken along the line 2-2 in Fig. 1. Fig. 3 is a further enlarged view in cross section of the shaft seal element alone shown in its as-molded and trimmed position. Fig..4 is a similarly enlarged view of the wear sleeve. Fig. 5 is a view similar to Fig. 2 of a modified form of the invention employing a differently shaped wear sleeve and a modified form of the outer portion of the outer seal of Fig. 2. Fig. 6 is a view in section of approximately half of the lower parts of a mold for molding the shaft seal, shown with the mold open and the case, the polytetra- fluoroethylene washer, and the raw elastomer placed in position. Fig. 7 is a similar view of the mold in its closed position. Fig. 8 is a fragmentary enlarged view in section of a portion of Fig. 7, showing the seal as molded and indicating the trim line. Description of a Preferred Embodiment As shown in Fig. 1 a unitized seal 10 of the invention is a continuous annular device. As shown in Figs. 1 and 2, the seal 10 comprises a sealing member 11, and a wear sleeve member 12, which are assembled together in a manner resulting in unitization, so that the seal is installed as a unitized assembly 10, rather than having separate installation of its two major components 11 and 12. The elastomeric seal member 11 preferably comprises three major elements which are best seen in Fig. 3, which presents the as-molded and trimmed sealing member 1 11. This member 11 comprises a metal case member 15, an 2 elastomeric member 16 which is bonded to the case 15, and 3 a polytetrafluoroethylene insert 17 which is bonded to the 4 elastomeric member 16. 5 The case 15 is a unitary annular metal member 6 shaped to provide a cylindrical outer portion 20 having 7 an outer surface 21 for leak-tight engagement in the bore 8 of a housing. The outer surface 21 is preferably coated 9 with a suitable bore-locking material, not shown. One end 10 22 of the portion 20 is free and the other end 23 is 11 curved back on itself to provide a short inner cylindrical 12 portion 24 with its outer surface 25 bearing against the 13 inner periphery 26 of the portion 20. The portion 24 has 14 an inner surface 27, and it is curved inwardly at its end 15 28 to provide a radial flange 30 having an outer or air- 16 side surface 31, an inner or grease-side surface 32, and 17 a radially inner end 33. To this end 33 and to the inner 18 portions of the surfaces 31 and 32 is bonded the elasto- 19 eric sealing element 16. The actual molding will be 20 described later, in conjunction with Figs. 6 and 7. 21 The elastomeric sealing element 16 may be of any 22 suitable elastomer; it is a unitary member having a radi- 23 ally extending portion 35 bonded to the surface 31 of the 24 radial flange 30, and an outer cylindrical portion 36 25 bonded to the surface 27 of the case 15. This cylindrical 26 portion 36 is provided near its axial end 37 with a 27 series, usually four, of inwardly directed projections 38 28 which provide short retaining members for holding the wear 29 sleeve member 12 in its unitized position. 30 The radially inner portion of the elastomeric 31 member 16 comprises two lip portions 40 and 41. The lip 32 portion 40 comprises an as-molded lip edge 42 which need 33 not be trimmed and which faces at an angle of about 45° 34 away from the radial flange 30 of the case 15. It serves 35 as the grease-retaining lip 40. Its lip edge 42 may have 36 a slight curvature and is preferably provided with a 37 series, preferably three, of short lip vents 43, which '.a are equally spaced around the periphery, and may be, and preferably are, approximately 0.005" deep by 0.125" wide. The purpose of these vents 43 is to permit the entry of grease from the bearing chamber into a cavity 44 in between the two lips to keep the lips lubricated. The amount of grease desired there is relatively small, and therefore the vent passages 43 are quite small, so that they do not significantly interfere with grease retention. The other sealing lip portion 41 is made consider- ably wider than the lip portion 40 to provide a good support for the polytetrafluoroethylene insert 17, which takes up approximately half the width of the lip portion 41 and which must be bonded to and securely retained by the elastomeric lip portion 41. Thus, the elastomer itself may be considered as having converging walls 45 and 46 and a recess having walls 47 and 48. Into the recess and flush with the walls 47 and 48 is the polytetrafluoroethylene member 17. The lip portion 41 and the tetrafluoroethylene member 17 have a common trimmed edge 50 which is not perpendicular to the wall 45 but is, instead, so trimmed that when the sealing member 11 is assembled on the wear sleeve member 12, the trimmed edge 50 will approach as closely as possible a right angle to the wear sleeve, as can be seen in Fig. 2. The limiting factor here is what the shape and dimensions of the seal enable the trimming knife to do without cutting any of the other parts. Typically this means that trim lies at an angle of about 30° to a plane parallel to the radial flange 30. The way in which the seal is made will be described later. In any event, the trimming results in an o iginally sharp sealing lip edge 51, what becomes blunted as the lip wears. The wear sleeve member 12 is a formed metal member, preferably made from the kind of sheet steel usually used for this type of installation, typically treated with phosphoric acid or some similar solution. This member 12, as shown in Fig. 4, has a wear sleeve 52 1 proper, the inner periphery 53 of which fits snugly on a 2 shaft, while its outer periphery 54 serves as the surface 3 upon which the seal lips 42 and 51 run, as can be seen in 4 Fig. 2. * One end 55 facing the bearing is a free end, while 5 at the other , end 56 the wear sleeve member 12 is curved 6 outwardly to provide a radially extending portion 57 7 followed by an angularly extending portion 58 that goes 8 back in axially, toward the opposite end 55, terminating 9 at an end 59. The ends 55 and 59 are cut off before the 10 forming. The angular portion 58 is shown extending at an 11 angle of about 45° to the radial portion 57, and the end 12 59 lies out beyond the projections 38 but spaced out from 13 the inner surface of the cylindrical portion 36. Thus, the 14 outer periphery 59 can be snapped into the four or more 15 protuberances or retaining members 38 to unitize the seal 16 10. The spacing apart of the members 38 and the flexi- 17 bility of the elastomer make assembly a very simple 18 matter. 19 When the members 11 and 12 are assembled to 20 complete the seal 10 (Fig. 2) the two lips 42 and 51 are 21 spread apart more widely than before (Fig. 3), and the 22 cavity 44 between them is somewhat reduced in height, but 23 is spread in width. The recesses 43 for admitting grease 24 into the cavity 44 are operative, and the polytetrafluoro- 25 ethylene sealing member 17 has its axially outer edge 50 26 substantially parallel to the radial portion 57 of the 27 wear sleeve member 12, as well as to the radial flange 30 28 of the seal case 15. 29 The portions 57 and 58 of the wear sleeve member 30 12 act as a deflector and as a slinger, to free the seal 31 as much as possible from water and corrosive liquids, as 32 well as from dirt and dust. 33 To obtain somewhat better operation of this 34 slinging-deflecting feature, the wear sleeve structure 60 35 shown in Fig. 5 may be used, although it is more difficult 36 to form and therefore somewhat more expensive. In this 37 instance, after a short radial portion 61 at the end of _.« 1 the wear sleeve proper 62, the metal has a portion 63 2 bent inwardly axially toward the opposite end of the wear 3 sleeve 62, at approximately 90° and then has a bent-out 4 portion 64 lying parallel to the radial flange 30, when 5 installed, and then a final portion 65 is bent back at an 6 acute angle to bring its end 66 out within the inner 7 diameter of the retention members 38. This bending back 8 results in leaving axially inside the members 38 the part 9 of the portion 65 which is of greater diameter than the 0 retaining members 38, though of lesser diameter than the 1 cylindrical surface 36 from which the retaining members 38 2 project. This structure provides an improved slinging 3 action, while taking up no more room. However, its practi- 4 cality depends partly on the necessity for any greater 5 slinging action, and on the additional costs involved. 6 As would probably be apparent anyway, the exterior 7 part of the case 15 may be at least partially coated with 8 elastomer, as is also shown in Fig. 5. Here, an outer 9 portion 70 of the elastomer is formed to cover the 0 exterior surface 71 of an inwardly stepped portion 72 of 1 the case. The rubber coating 70, since it is able to 2 accommodate itself to the bore diameter by some flow 3 towards its end, is made a little larger in diameter than 4 the remaining portion 73 of the bore-engaging portion of 5 the metal case. 6 Going now to the method of manufacture of the 7 seal, a preferred such method incorporates a four-piece 8 mold 75 as shown in Figs. 6 and 7. The mold 75 is shown 29 in a particular orientation which will be used for 0 description, although a different orientation is possible. 31 A stationary mold base 80. is shaped to provide a bottom 32 planar surface 81 with an inner cylindrical surface 82 and 33 an outer cylindrical surface 83. The inner cylindrical 34 surface 82 leads up to a horizontal planar annular surface 35 84, which, in turn, leads out to a short cylindrical 36 surface 85, and then to an inclined frustoconical portion 37 86. At the outer end of the portion 86 is a shelf 87 ^a 1 connected by a step 88 to a short case-engaging planar 2 rest 89. From there, a radius portion 90 leads to a 3 cylindrical portion 91 terminating at a planar shoulder 4 92. The outer edge of the shoulder 92 terminates at a 5 frustoconical outer surface 93, at the lower end of which 6 is a flash trap 94 followed by a planar shelf 95 leading 7 to the outer cylindrical surface 83. 8 A second, outer, mold member 100 is placed partly g around and partly upon the base mold member 80. It has an 0 outer generally cylindrical surface 101 and a lower flat 1 annular face 102 which engages the annular shelf 95. It 2 also has a frustoconical surface 103 bearing against the 3 frustoconical surface 93 of the first mold member 80. 4 Above that is a short cylindrical portion 104 going up to 5 another frustoconical surface 105 that leads to an upper 6 planar face 106 extends out to its outer surface 101. The metal case 15 is preferably placed with its 8 outer surface 21 bearing against the cylindrical portion 104 of the mold member 100 and with the surface 32 of its radial flange 30 resting upon the rest 89, while most of the inside surface 26 the case portion 15 is spaced away from the cylindrical portion 91. A third, inner, mold member 110 has a stepped generally cylindrical inner through opening with a lower cylindrical surface 111, a step 112, and an upper cylin- drical surface 113. A mold pin 114 has a head 115 engaging the step 112 and forcing a lower annular face 116 of the mold member 110 snugly against the annular surface 84. A cylindrical face 117 engages the cylindrical surface 85, and a frustoconical surface 118 engages and overlies the frustoconical surface 86 of the first mold member 80. However, the upper and outer end of the surface 118 is shaped to provide a cavity 120 between the two mold members 80 and 110 adjacent to the shelf 87. The cavity 120 provides the as-molded grease-retaining lip portion 40. At its upper end, the cavity 120 is terminated, and a frustoconical portion 121 leads upwardly to an inwardly 1 extending ledge 122. The ledge 122 then leads to a nearly 2 cylindr ical tapered portion 123 ending in an annular 3 planar portion 124 which leads in to the inner periphery 4 113. 5 A polytetrafluoroethylene washer 125, which 6 preferably has been- acid etched on one surface provided 7 and then with a coating of bonding cement there and on its 8 outer periphery 126, is placed on top of the ledge 122, 9 with the etched and coated surface facing up and with its 0 inner periphery 127 abutting the tapered portion 123. The 1 washer 125 extends out beyond the ledge 122 and overhangs 2 a portion of the frustoconical surface 121. Atop the 3 washer 125# is placed a ring 128 of uncured elastomer 4 calculated to provide the proper amount for filling the 5 molded cavities provided for the elastomer. 6 A fourth or upper mold member 130 is attached to 7 an upper mold pin 131 having a head 132 that partially 8 compresses a series of springs 133 against a lower 9 shoulder 134 of the member 130. LikS the first mold member 0 80, the member 130 has a flash receiving cavity 135 at the 1 outer end of a planar lower face portion 136 and at the 2 inner end of a tapered portion 137 that mates with the 3 tapered portion 123 of the third mold member 110 when the 4 mold 75 is in its closed position. At the lower end of the 5 tapered portion 137 is a planar annular surface 138 6 leading to a frustoconical portion 140, the surfaces 138 7 and 140 defining part of the mold cavity for the dirt- 8 excluding lip 41. The surface 140 is succeeded by a short 9 radial portion 141 followed by a cylindrical step 142 0 leading to a short annular planar surface 143, from the 1 outer end of which a tapered portion 144 leads outwardly 2 and upwardly. The tapered portion 144 mates with the 3 tapered portion 105 of the second mold member 100 and has 4 another flash-receiving cavity 145 at its outer end. 5 Beyond that is a planar surface 146 that mates with the 6 surface 106 of the second mold member 100 and leads to an 7 outer cylindrical surface 147. ■ M . When the heated mold is closed during the progress from the position shown in Fig. 6 to that of Fig. 7, the mold cavities are defined, and simultaneously the elasto- mer is caused to flow thereinto. If there is any excess elastomer it. flows into the flash-receiving cavities 135 and 145. This flask is relatively easily removed from the molded seal. However, no flash forms on the as-molded lip 40. During this operation the elastomer and the fourth or upper mold member 130 act upon the polytetrafluoro- ethylene washer 125 to force its overhanging portion flush against the frustoconical surface 121 while bonding the elastomer to it. After the mold 75 is closed, it is held closed until cure of the elastomer has been completed, and then it is parted and the sealing member is ejected by conventional means. As will be seen from the mold drawing, the inner portion of the polytetrafluoroethylene washer 125 and the elastomer there must be trimmed off. The trimming is along the line 150 in Fig. 8, leaving the edge 50 shown in Fig. 3, so that the inner periphery of the lip edge 52 is smaller in diameter than that of the the grease-retaining lip edge 51, the trimming being made, as stated before, at an angle of about 30° to the plane of the radial flange 30 and, in any event, such that the surface 50 will become nearly a right angle when the seal is unitized. The wear sleeve member 12 is made by conventional forming means to the desired shape, and is, as already been said, snapped into the oil seal member 11, so that the retaining members 38 thereafter hold it in place. The seal assembly 10 can, if actually need be, taken apart, but this is far from normal, and it is almost always left together. It will not come apart accidentally because of the retention members 38. To those skilled in the art to which this inven- tion relates , many changes in construction and widely differ ing embodiments and applications of the invention 1 wil l suggest themselves without departing from the spirit 2 an d scope of the invention. The disclosures and the 3 d escr iptions herein are purely illustrative and are not 4 intended to be in any sense limiting. 5 What is claimed is: 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 ~ 3 34 35 36 37 -.a

Claims: - 17 - 1. A unitized grease seal, including in 2 combination: 3 a seal member having 4 a one-piece metal case having a cylindrical bore- 5 sealing portion with an inner surface and an inwardly 6 extending radial flange, in between the ends of said bore- 7 sealing portion, having a radially inner end, an air-side 8 radial surface, and an opposite grease-side radial 9 surface, 10 a molded elastomeric member bonded to said metal 11 case and having a radially extending portion bonded to 12 said air-side radial surface, an outer generally cylin- 13 drical portion bonded to said inner surface of the bore- 14 sealing portion on the air side of said flange and 15 providing a series of radially inwardly extending retain- 16 i n 9 portions spaced circumferentially from each other, 17 and 18 said elastomeric member also having an inner 19 portion extending radially inwardly of said inner end of 20 said radial flange and having two diverging lip portions 21 with a cavity between them, one said lip portion providing 22 ** - grease retention lip having small spaced-apart shallow 23 indentations enabling passage of small amounts of grease 24 into said cavity, the other said lip portion having a 25 polytetrafluoroethylene insert bonded to said elastomeric 26 member and providing the sealing edge portion of a dirt- 27 excluding lip, and 28 a one-piece metal wear sleeve member having a 29 radially inner shaft-engaging cylindrical portion having 30 an outer surface engaged by said lips and having a larger 1 outer diameter than the free-standing inner diameter of 2 said lips, so that assembly of the wear sleeve on the seal 3 member causes further spreading-apart of said two lips, 4 said dirt-excluding lip when in position on said wear 5 sleeve having an end wall on its air side that is sub- 6 stantially perpendicular to said wear sleeve's outer 7 surface, •M. said wear sleeve member also having a radially 2 outwardly extending flange on its air-side end, with an 3 axially inturned portion having an outer portion spaced 4 radially inwardly from the outer generally cylindrical 5 portion of said elastomeric member but extending radially 6 outwardly beyond the radially inner extremities of said 7 retaining portions, so that during assembly, the wear 8 sleeve flange's inturned portion can be snapped into the 9 axially extending space between said retaining portions 0 and the elastomer-covered radial flange. 1 2 2. The grease seal of claim 1 wherein said wear 3 sleeve's flange has a truly radial portion where it meets 4 said cylindrical wear sleeve portion, extending beyond 5 said end wall of said dirt-excluding lip followed by an 6 angularly extending portion, going toward said case's 7 radial flange and ending at its radially outermost, 8 axially innermost point. 9 0 3. The grease seal of claim 1 wherein said wear 1 sleeve's flange has a truly radial portion where it meets 2 the wear sleeve's cylindrical portion, extending beyond 3 said dirt-excluding, lip followed by an axially inwardly 4 extending portion going toward said case's radial flange, 5 followed by a radially extending portion parallel to said 6 case's radial flange and extending out radially beyond 7 said retaining portions, followed by an axially.outwardly 8 and radially inwardly extending angular portion ending 9 substantially flush axially with the end of said bore- 0 sealing portion and radially within said retainer 1 portions. 2 33 34 35 36 37 ^8 1 4. A unitized dual-lip grease seal, including in 2 combination: 3 a seal member having 4 a one-piece metal case with a cylindrical bore- 5 sealing portion having an inner surface and*an inwardly 6 extending radial flange, in between the ends of said bore- 7 sealing portion, having a radially inner end, an air-side 8 radial surface and an opposite grease-side radial 9 surface, 10 a molded elastomeric member bonded to said metal 11 case and having a radially extending portion bonded to and 12 completely covering said air-side radial surface, an 13 outer generally cylindrical portion bonded to and covering 14 that portion of said inner surface of the bore sealing 15 portion which lies on the air side of said flange and 16 providing a series of radially inwardly extending retain- 17 ing portions spaced circumferentially from each other, 18 said elastomeric member also having an inner 19 portion extending radially inwardly of said inner end and 20 bonded thereto and having two diverging lip portions, 21 meeting, as molded, at about 90° at a point spaced 22 radially in from said inner end and with a cavity between 23 them, one said lip portion providing a grease retention 24 lip and the other dirt-excluding lip, and 25 a one-piece metal wear sleeve member having a 26 radially inner shaft-engaging cylindrical portion having 27 an outer surface engaged by said lips and having a larger 8 outer diameter than the free-standing inner diameter of 9 said lips, so that assembly of the wear sleeve on the seal 0 member causes further spreading-apart of said two lips, 1 said dirt-excluding lip when in position on said wear 2 sleeve having an end wall on its air side that is sub- 3 stantially perpendicular to said wear sleeve's outer 4 surface, 5 said wear sleeve member also having a radially 6 outwardly extending flange on its air side end, with an 7 axially inturned portion having a radially outermost *.& portion spaced inwardly from the outer generally cylin- drical portion of said elastomeric member but extending radially outwardly beyond the radially inner extremities of said retaining portions, so that, during assembly, the wear sleeve flange' s inturned portion can be snapped into the space between said retaining portions and the elastomer-covered radial flange. 5. The grease seal of claim 4 wherein said grease- retaining lip is provided with spaced-apart shallow indentations. 6. The grease seal of claim 4 wherein said dirt- excluding lip has a polytetrafluoroethylene insert bonded thereto and providing the sealing edge. 7. A unitized grease seal, including in combination: a seal member having a one-piece metal case with a cylindrical outer portion defining a wall with, an outer surface adapted to be press-fitted into a stationary bore and an inner surface, a reverse cylindrical portion extending back from one end of said wall and having an outer surface bearing against said inner wall surface and an inner surface, said reverse portion being much shorter than said outer portion, and an inwardly extending radial flange leading from the axially inner end of said reverse portion and having a radially inner end, an outer face on the air side of said seal and continuous with the inner face of said reverse portion, and an opposite inner face on the grease side of said seal, a molded elastomeric member bonded to said metal case and having a radially extending portion bonded to and covering said outer face of said radial flange, an outer generally cylindrical portion bonded to and covering the inner surface of said reverse portion and providing a series of radially inwardly extending retaining por tions spaced circumferentially from each other , said elastomer ic member also having an inner portion extending radially inwardly of said radially inner end of said radial flange and bonded thereto and having two diverging lip portions, meeting, as molded, at about 90° at a point spaced radially in from said inner end and with a cavity between them, one said lip portion being on the grease side of the seal and having a grease-retention lip provided with a ser ies of spaced-apart shallow indentations enabl ing passage of small amounts of grease into said cavity, the other said lip portion providing a dirt-excluding lip portion having a cylindrically extend- ing recess therein, and a polytetrafluoroethylene sealing lip member f itting in said recess and bonded to said elastomer ic member and providing the sealing edge portion of said dirt excluding lip, said lip having an end wall on its ai r side, a one-piece metal wear sleeve member having a radially inner cylindrical portion with an inner surface adapted to be press fitted on a rotatable shaft and an outer surface engaged by both said lips and having a larger outer diameter than the inner diameter of said lips before assembly with said wear sleeve member, so that assembly of the wear sleeve on the seal member causes further spreading-apart of said two lips, the end wall of said dirt-excluding lip, when said lip is in position on said wear sleeve being substantially perpendicular to said wear sleeve's outer surface, said wear sleeve member also having a flange portion extending radially outwardly from the air side end of the wear sleeve's cylindrical portion and an inturned portion at an angle to said radial flange and extending axially toward said case's radial flange and having an outer end spaced radially inwardly from the outer gener- 1 ally cylindrical portion of said elastomeric member but 2 extending radially outwardly beyond the radially inner 3 extremities of said retaining portions, so that the 4 inturned portion of said wear sleeve member can be snapped 5 into the space between said retaining portions and said 6 radial flange of said metal case. 7 8 8. The grease seal of claim 7 wherein said wear 9 sleeve's flange has a truly radial portion where it meets 0 said cylindr ical wear sleeve portion, extending beyond 1 said end wall of said dirt-excluding lip followed by an 2 angularly extending portion, going toward said case ' s 3 radial flange and ending at its radially outermost , 4 axially innermost point. 5 6 9. The grease seal of claim 7 wherein said wear 7 sleeve' s flange has a truly radial portion where it meets 8 the . wear sleeve ' s cylindr ical portion, extending beyond 9 said dirt-excluding lip, followed by an axially inwardly 0 extending portion going toward said case' s radial flange, 1 followed by a radially extending portion parallel to said 2 case' s radial flange and extending out radially beyond 3 said retaining portions, followed by an axially outwardly 4 and radially inwardly extending angular portion ending 5 substantially flush axially with the end of said bore- 6 sealing portion and radially within said retainer 7 portions. 8 9 10. The grease seal of claim 7 where in said 0 cylindrical outer portion is stepped and said elastomer ic 1 member has a portion extending from said outer generally 2 cylindrical portion to the outer surface of said wall and 3 bonded thereto to provide a bore-engaging outer 4 periphery. 5 6 7 11. A grease seal member, including in combination: a one-piece metal case with a cylindr ical bore- sealing portion and an inwardly extending radial flange having a radially inner end, a molded elastomer ic member bonded to said metal case and having an inner portion extending r adially inwardly of said radial flange and having two diverging lip portions , meeting, as molded, at about 90° at a point in line with said flange and with a cavity between them , one said lip portion providing a grease-retention lip having spaced-apart small relieved indentations enabling passage of small amounts of grease into said cavity, the other said lip portion having a polytetrafluoroethylene insert bonded to said elastomeric member and providing the sealing edge portion of a dirt-excluding lip. 12. The sealing member of claim 11 wherein said dirt excluding lip has an air-side end wall , which upon installation of said sealing member on a contacting surface for. sealing therewith , with further spreading- apart of said two lips , becomes substantially perpendicu- lar to said contacting surface. 13. A method for making a unitized dual-lip shaft seal for sealing in grease and sealing out dirt and other foreign matter, with one lip having a polytetrafluoro- ethylene insert sealing member, comprising: seating on a first mold member a one-piece metal case, while seating the case's outer bore-engaging cylin- drical portion against a second mold member, the case having an axially inset radial flange with an air-facing side and a grease-facing side, appropriate parts of said case being covered with elastomer-bonding cement, engaging a third mold member with said first mold member so as to define between them a cavity for molding to finished size and shape a grease-facing lip at an 1 angle of about 45° to said radial flange, and also provid- 2 ing one surface of another cavity for an air-facing lip, 3 sloping in the opposite direction at an angle of about 45° 4 to said radial flange, so that the two cavities meet at 5 about 90° to each other, said surface leading to a ledge 6 spaced away from said radial flange and parallel to the 7 plane thereof , said ledge ending at an inner cylindrical 8 boundary, 9 placing a flat washer of polytetrafluoroethylene 0 on said ledge with an inner circumference of said washer 1 engaging said boundary and an outer circumference extend- 2 ing beyond said ledge and overhanging a portion only of 3 said sloping surface, with appropriate surface portions of 4 said washer being treated to enhance bonding of elastomer 5 thereto, 6 positioning a ring of uncured elastomer on top of 7 the portion of said washer supported by said ledge, 8 bringing a fourth mold member toward and against 9 said second and third mold members, while all said mold 0 members are heated to a molding and curing temperature, so 1 as to define the remainder of the mold cavity for the 2 air-facing lip and to define a further cavity having a 3 radial portion next to said radial flange and an outer 4 cylindrical portion next to the cylindrical portion of 5 said case and shaped to provide a set of circumferentially 6 spaced-apart cavity portions extending radially inwardly 7 to provide retention members, all while forcing said 8 elastomer to flow into all the mold cavities and also to 9 flex the overhanging portion of said washer into engage- 0 ment with said sloping surface and to initiate bonding of 1 the elastomer to said case and said washer, 2 curing said elastomer to a desired amount so that 3 it holds its shape and completes the bonding to said case 4 and said washer, to produce a shaft sealing member with a 5 grease-facing lip molded to its final shape and an air- 6 7 ■ XΛ fac ing lip having a portion extending generally inwardly therefrom, said shaft sealing member also having a set of retention members spaced away from said radial flange, then opening said mold and removing said shaf t sealing member , tr imming said air-facing lip to a desired length at a trimmed edge having a desired angle so that, when the product is unitized, the trimmed edge is nearly parallel to said radial flange, forming a one-piece metal wear sleeve having a cylindr ical portion for engagement with both said lips and of a size to force spreading apart of those lips and, as a result , moving the tr immed edge to its said nearly- parallel position, said wear sleeve also having a radially outwardly extending por tion of a size enabling unitization, assembling said wear sleeve and shaf t sealing member together , with the sleeve ' s radially outwardly extending portion on the grease side of said shaft sealing member , the lips being in engagement with the cylindr ical portion of said wear sleeve, and snapping the radially outwardly extending portion into the space between said retention members and sa id elastomer-covered radial flange , said retention members thereafter hindering retraction of the wear sleeve f rom said shaft-sealing member . 14. A method for making a dual-lip shaft seal for sealing in grease and sealing out dirt and other foreign matter, with one lip having a polytetrafluoroethylene insert sealing member, comprising: seating on a first mold member a one-piece metal case, while seating the case's outer bore-engaging cylin- drical portion against a second mold member, the case having a radial flange with an air-facing side and a grease-facing side, appropriate parts of said case being covered with elastomer-bonding cement. engaging a third mold member with said first mold 2 member so as to define between them a cavity for molding 3 to finished size and shape a grease-facing lip at an 4 angle of about 45° to said radial flange, and also provid- 5 ing one surface of another cavity for an air-facing lip, 6 sloping in the opposite direction at an angle of about 45° 7 to said radial flange, so that the two cavities meet at 8 about 90° to each other said surface leading to a ledge 9 spaced away from said radial flange and parallel to the 0 plane thereof, said ledge ending at an inner cylindrical 1 boundary, 2 placing a flat washer of polytetrafluoroethylene 3 on said ledge with an inner circumference of said washer 4 engaging said boundary and an outer circumference extend- 5 ing beyond said ledge and overhanging a portion only of 6 said sloping surface, with appropriate surface portions of 7 said washer being treated to enhance bonding of elastomer 8 thereto, 9 positioning a ring of uncured elastomer on top of 0 the portion of said washer supported by said ledge, 1 bringing a fourth mold member toward and against 2 said second and third mold member, while all said mold 3 members are heated to a molding and curing temperature, so 4 as to define the remainder of the mold cavity for the 5 air-facing lip, all while forcing said elastomer to flow 6 into all the mold cavities and also to flex the overhang- 7 ing portion of said washer into engagement with said 8 sloping surface and to initiate bonding of the elastomer 9 to said case and said washer, 0 curing said elastomer to a desired amount so that 31 it holds its shape and completes the bonding to said case 32 and said washer, to produce a shaft sealing member with a 33 grease-facing lip molded to its final shape and an air 34 facing lip having a portion extending generally inwardly 35 therefrom, 36 then opening said mold and removing said shaft 37 sealing member, and ^8 ^ trimming said air-facing lip to a desired length. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 -M.

Inventors: BROOKS DAVID R, NASH STEPHEN E, PICHLER GERALD T, BROOKS, DAVID, R., NASH, STEPHEN, E., PICHLER, GERALD, T.
Applicants: FEDERAL MOGUL CORP, FEDERAL-MOGUL CORPORATION
Application year: 1985
Main classification: F16J15
IPC codes: F16J15