BEARING SEALS

Abstract: The present invention relates to a bearing seal (9, 9') incorporating an annular body (10) in sealing contact with the outer ring of a bearing (4), and a sealing, resilient annular member (11) fitted to said annular body and projecting therefrom to sliding sealing contact against a co-operating sealing surface (2) spaced apart from the outer bearing ring (4) and thereby sealingly bridging the annular space between the two bearing rings (3, 4), wherein the annular body (10) is attachable to the outer bearing ring (4) by means of an annular bulge (14) provided on the resilient member (11) and being attachable by snap-action in a circumferential groove (8') in the inner envelope surface of the outer race ring (4) of the bearing.

Description: 1 TITLE BEARING SEALS DESCRIPTION Technical field The present invention relates to bearing seals of the type incorporating an annular body in sealing contact with the outer ring of a bearing, and a sealing, resilient annular member fitted to said annular body and projecting therefrom to sealing contact against a co-operating sealing surface adjacent the opposite bearing ring. The object of the present invention is to obtain a possibility of externally securing a bearing seal to a bearing and to improve the sealing properties of the bearing seal thereby. A further object is to obtain a possibility of replacing the seal in a simple way at repair, on the after-market, and to provide sealing and bearing as one part in primary manufacturing. Background of the invention Seals for bearing arrangements are used to prevent solid contaminants and moisture from penetrating into the bearing and at the same time to retain the lubricant in the bearing or bearing arrangement. Bearing seals generally provide a minimum of friction and cause a minimum of wear whilst maintaining their efficiency even under the most unfavourable conditions so that bearing performance and life are not adversely affected. Bearings can be provided with seals which are made integral with the bearing and seals which are positioned outside the very bearing. The seals integral with the bearing are delivered ready sealed and lubricated from the manufacturer and they are generally well suited for preventing penetration of contaminants from the outside in common environments. 2 In cases with extraordinary quantities of contaminants, such as e.g., at bearings for use in agricultural equipment there is, however, required particular, externally mounted seals. When mounted at the manufacturer of the implement to which it belongs, the skilled person in the art will of course mount and seal the bearing in a correct way, so that the bearing will operate correctly to ascertain external contaminants from entering the bearing. However, when such bearings shall be replaced this will often take place in the field, i.e., not always by personnel skilled in the art, and thus there is a risk that the seal will be incorrectly applied, leading to undue contamination of the inner of the bearing, and leakage or destruction of the lubricating properties. The ultimate course of action is a breakdown of the bearing. Thus, as indicated above, one object of the present invention is to provide a combination of bearing and external seal which can be mounted and handled as a unit. This is advantageous not only for untrained personnel at after-mounting, but also at manufacture of the implement to which the sealed bearing shall be mounted, as such a unit means easy mounting and a fewer separate components to store, handle and mount. Many factors have to be considered when choosing the right type of seal, such as type of lubrication, peripheral speed at the sealing surface, horizontal or vertical shaft arrangement, available space, friction in the seal, costs and other considerations. Bearing seals are commonly used to protect bearings mounted on shafts against dirt and water and are particularly used in heavy environments, such as agricultural applications, heavy industries, etcetera. Such seals are known in a great variety of embodiments. One main type is a sliding seal, which incorporates a sealing body of a resilient material being affixed to one of the bearing rings and at the free end having at least one sealing lip slidingly contacting the other bearing ring or a member attached to said other bearing ring. This type of seals are provided as integral seals or as external seals. Another main type of seals, often used as external seal, comprises two bodies, a first body connected to the rotating bearing ring and a second body connected to the stationary bearing ring. The two bodies form together a labyrinth seal, preventing penetration of contaminants, 3 moisture and lubricant. Bearing seals being combinations of sliding seals and labyrinth seals are also used. The resilient member can be made of one, two or more parts, depending on the construction of the seal as such. A common feature is the resilient sealing lip facing a co-operating sealing surface and which sealing lip in many cases is urged against the co-operating sealing surface by means of an annular spring. Different sealing arrangements are known from EP-A1-0 241 581 ; EP-A2-0 519 654; and US -A-5, 024,449, which references show different types of seals attached to roller bearings, and ball bearings. The present seals are no real combinations with the bearings, and there is a request for obtaining a bearing incorporating a seal, in particular a ball bearing having a groove in the outer raceway. Description of the present invention It has now been found possible to solve this problem by means of the present invention, which is characterized in that the annular body is attachable to the outer bearing ring by means of an annular bulge provided on the resilient member and being attachable by snap-action in a circumferential groove, preferably in the inner envelope surface of the outer race ring of the bearing. Further characteristics will be evident from the accompanying claims. By means of the present invention a cassette seal can be readily attached to its bearing by a simple snap-in action, thereby providing a more simple attachment thereof, together with improved sealing capacity. The present invention will now be described with reference to the attached drawing showing different embodiments of the invention, however, without the invention being restricted thereto. 4 In the drawings FIG. 1 shows a cross-sectional view of a portion of a ball bearing provided with a bearing seal according to a first embodiment of the present invention. FIG. 2 is a corresponding view showing a portion of a ball bearing with a bearing seal according to a second embodiment of the invention. FIG.s 3-5 show in corresponding views three further, slightly modified embodiments in accordance with the present invention. In FIG. 1 is shown a ball bearing 1 arranged on a shaft 2 and comprising an inner race ring 3 and an outer race ring 4 with a set of balls 5 provided between said rings and being kept separated and guided in a cage 6. At one axial side of the bearing the space between the two race rings 3, 4 is sealed off by means of a commonly used integral seal 7, being attached in a circumferential annular groove 8, normally provided in the inner envelope surface of the outer race ring 4 axially outside the balls 5. At the opposite axial side of the ball bearing 1 is positioned a cassette seal 9, which is placed outside the bearing, and which incorporates a cylindric, annular body having substantially the same outer diameter as the ball bearing 1. The cylindrical annular body incorporates a shield portion 10, and a resilient member 11 fitted to the shield member 10 and having a sealing lip 12, arranged to be in sliding and sealing contact with the envelope surface of the shaft 2, when mounted to the bearing 1. In a common manner an annular spring member 13 ' is arranged to urge the lip 12 of the resilient member 11 against the co-operating sealing surface, i.e. in this case the envelope surface of the shaft 2. The resilient member 11 has an outwardly facing edge provided with a bulge 14, which can be inserted in the existing annular groove 8' on the inner envelope surface of the outer race ring 4 by snap-action thus that the seal 9 will be detachably retained in the groove 8' when subjected only to moderate or low external forces. Thereby the seal 9 will be easily attachable to the bearing without the need of providing particular means or elements for attachment of the external seal to the bearing. The radially outer edge of the shield portion 10 of the seal 9 is preferably provided with a resilient lining 15 for increasing the grip and sealing effect against a (not shown) seat in which the bearing with seal is to be mounted. 5 In FIG. 2 is shown a slightly different embodiment of the invention, wherein the same reference numerals have been used for elements common to both embodiments. Thus the embodiment according to this figure incorporates a bearing 1 arranged in a proper, not further shown manner on a shaft 2 and having inner and outer race rings 3,4, balls 5 guided in a cage 6 provided therebetween, an integral lip seal 7, known per se, arranged at one axial side outside the balls 5 in a groove 8 in the outer race ring 4 and a cassette seal 9' fitted in a groove 8' at the opposite axial side of the bearing. This cassette seal 9' incorporates an annular shield portion 10 and a resilient member 11 fitted to the shield member 10 and having a sealing lip 12, arranged to be in sliding and sealing contact with the envelope surface of a flange 17 of a further cylindrical annular body 16 fixed to the shaft 2 via cooperating threads 18. The annular body 10,14 and the further annular body 16 thereby are concentrically arranged. The two annular bodies 12 and 14 form together a space between them, in which the lip 12 of the resilient member 11 is positioned in sliding and sealing contact with the flange 17 of the further annular member 16. An annular spring 13 is arranged to press the sealing lip towards sealing position. The resilient member 11 can be vulcanized to the shield member 10 if so desired. The outwardly facing edge of the resilient member 11 is provided with a bulge 14, which fits into said groove 8' of the outer race ring 4 of the bearing 1, by means of which the cassette seal 11 can be readily attached to the bearing 1 by a snap-action thereby providing easy mounting and correct tight sealing. Although this embodiment incorporates two separate elements, which are not fixedly attached to each other, the friction between the sealing lip 12 and its co-operating sealing surface 17 is high enough to maintain the two elements as a unit under normal handling, also prior to its mounting to the bearing. The embodiment shown in Fig. 3 is intended for applications wherein one requirement is that the sealed bearing shall have such a small axial width as possible and this embodiment incorporates a ball bearing 1 mounted on a shaft 2 and having an inner race ring 3, an outer race ring 4, a number of balls 5 provided between the race rings and guided by a cage 6'. In this embodiment the cage 6' is a cage of the type having a ring portion and a number of prongs extending axially therefrom and forming between 6 adjacent prongs axially open pockets for the balls 5. By using such a cage the space between the race rings 3, 4 at one axial side of the row of balls will be free from cage portions, which differs from the embodiments according to FIGs. 1 and 2. One side of the bearing - the side towards which the ring of the cage 6' is turned - has a sealing arrangement 7, 8, corresponding to that of the previous embodiments, whereas the other side of the bearing has a seal 9a incorporating an annular shield portion 10a and a resilient member 1 la fitted thereto and bridging the space between the race rings 3, 4. The resilent member is provided with an annular bulge 14a, which is received in a circumferential groove 8' in the inner envelope surface of the outer race ring 4. The bulge 14a is so dimensioned that it can be inserted into said groove 8' by snap-action and thus that it is retained in position during normal operation of the bearing. The resilient member 11a is also provided with a sealing lip 12a, arranged to slide against the land 3 a of the inner race ring 3. The seal 9a is further provided with a portion 19 extending radially outwards from the bulge 14a and being offset axially so far from this that the face of said radial seal portion 19 will engage the side face of the outer race ring when the bulge is positioned in the groove 8a. At assembly of the sealed bearing it is therefor easy to push in the seal to its correct position. Fig. 4 shows an embodiment of the sealed bearing, wherein the bearing is arranged in a housing 21, only a part of which is shown. The arrangement in this embodiment is designed in the same manner as that shown in Fig. 3, with the shield 10b, the resilient member 1 lb and a sealing lip 12b sealingly sliding against the land of the inner race ring of the bearing, and with an annular bulge 14b fitted by snap-action in the internal groove in the outer race ring. In this embodiment the resilient member l ib has a further sealing lip 20 arranged to engage the side face of the inner race ring 3. The outer radial portion 19 of the seal engages the side face of the outer race ring 4, and the radially outermost portion of the seal is provided with a cylindrical portion 22 engaging the seat in the housing 21. Fig. 5 shows an embodiment similar to that according to Fig. 4, with the difference that the seal has no cylindrical portion 22, but instead an annular bead 23 arranged to engage 7 a radial surface of the housing 21 , when the bearing is mounted in the housing with the seal in correct position. The other portions of the seal, here shown with the suffix "c", are otherwise similar or have the same function as . the corresponding members, having the suffix "b" in Fig. 4. With the designs shown in Fig.s 4 and 5 the sealed bearing unit will be securely centered in the bearing housing and the engaging portions 22 and 23, respectively, will also provide a sealing effect preventing dirt and moisture from reaching the surface of the bearing housing in which the bearing is seated. The invention is not limited to the embodiments shown in the drawings and described in connection thereto, but modifications and variants are possible within the scope of the appended claims. Thus the seal has been described in connection with a ball bearing, however, a great number of other types of bearings can be contemplated for the use, such as roller bearings, needle bearings, and others.

Claims: CLAIMS 1. A bearing seal (9,9',9a) incorporating an annular body (10, 10a, 10b, 10c) in sealing contact with the outer ring of a bearing (4), and a sealing, resilient annular member (l l,Ha,l lb,l lc) fitted to said annular body and projecting therefrom to sliding sealing contact against a co-operating sealing surface (2;17;3a) spaced apart from the outer bearing ring (4) and thereby sealingly bridging the annular space between the two bearing rings (3, 4), characterized in that the annular body (10,10a, 10b,10c) is attachable to the outer bearing ring (4) by means of an annular bulge (14, 14a, 14b, 14c) provided on the resilient member (11,1 la,l lb,l lc) and being attachable by snap-action in a circumferential groove (8') preferably in the inner envelope surface of the outer race ring (4) of the bearing. 2. A bearing seal as claimed in claim 1, characterized in that the annular body (10, 10a, 10b, 10c) is provided with a radially extending wall portion (19) axially displaced from the annular bulge (14,14a,14b,14c) such a distance that it in mounted position engages the side surface of the outer bearing ring (4). 3. A bearing seal as claimed in claim 1 or 2, characterized in that the co-operating sealing surface is constituted by the envelope surface of a shaft (2) supported by the sealed bearing ( 1 ). 4. A bearing seal as claimed in claim 1 or 2, characterized in that it comprises a further cylindrical annular body (16), arranged to be brought onto and in sealing contact with a shaft (2) supported by the sealed bearing (1), said further cylindrical annular body having a flange (17) constituting said co-operating sealing surface. 9 5. A bearing seal as claimed in claim 4, characterized in that the said cylindrical, annular body (10) and the further cylindrical annular body (16) are kept together as a unit by the friction between the sealing resilient annular member (11) and the said flange (17). 6. A bearing seal as claimed in claim 1 or 2, characterized in that the co-operating sealing surface is constituted by the inner envelope surface (3 a) of the bearing inner ring (3). 7. A bearing seal as claimed in anyone of the preceeding claims, characterized in that said annular body (10b, 10c) has a portion (22;23) extending axially outside the outer bearing race ring (4), said body portion being provided with means for sealing contact, in axial and/or radial direction against a bearing housing (21) surrounding the outer bearing ring (4).

Inventors: BUNDGART ASBJOERN, BUNDGART, ASBJOERN
Applicants: SKF SVERIGE AB
Application year: 1998
Main classification: F16C33
IPC codes: F16C33, F16C35