Perfected sealing and guard ring for rolling bearings

Abstract: A sealing and guard ring for a rolling bearing, the ring presenting an elastomeric rubber element (14) cured on to an annular metal armature (8) presenting, on the outer radial edge, an axial bead (24) for supporting a peripheral rib (16) and a radial projection (20) of the rubber element (14); the rib (16) is housed and secured by friction inside an annular groove (17) on the outer ring (1) of the bearing; the radial projection (20) cooperates with an edge of the outer ring to provide for improved sealing of the outer ring; the inner radial edge of the rubber element presents a sealing lip (25) sliding interferentially on the rotary inner ring (3) of the bearing (4); a further two projections (27, 29) of the rubber element, connected to the sealing lip (25), cooperate respectively with the inner ring (3) of the bearing (4), and with a centrifugal element (30) rotating integral with the inner ring (3); and the sealing ring according to the invention is used, in particular, on farm and/or earth-moving equipment subjected to severe solid and liquid pollution.

Description: The present invention relates to a sealing and guard ring for rolling bearings, particularly heavy duty bearings of farm and/or earth-moving equipment, subjected regularly to external pollutants such as abrasive dust, soil and/or vegetable particles, muddy water, etc. A sealed rolling bearing according to the preamble of claim 1 is known by EP-A-337 321. Numerous sealing ring designs are known for meeting the demands of a wide range of applications. One particular type of ring for sealing and protecting rolling bearings from external pollutants comprises a radial annular armature made of metal and presenting a cylindrical peripheral bead, which is forced on to the normally stationary outer ring of the bearing; and an elastomeric membrane is co-molded on to the armature, and terminates with a circular inner edge in the form of a sealing lip, which is fitted with a small amount of interference inside a cylindrical seat to act as a sliding seal on the rotary inner ring of the bearing. Though effective under normal working conditions, seals of the above type are unsuitable for applications involving severe pollution, such as farm and/or earth-moving equipment subjected to abrasive dust, soil or muddy water. It is an object of the present invention to provide a sealing and guard ring for rolling bearings, designed to overcome the drawbacks typically associated with known sealing rings. It is a further object of the present invention to provide a sealing and guard ring designed to effectively safeguard the bearings of farm and/or earth-moving equipment against particularly harmful external pollutants. According to the present invention, there is provided a sealed rolling bearing of the above-mentioned type which is structured in accordance with the second part of claim 1. A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawing, which shows a radial section of part of the sealing ring according to the invention, the remaining part being symmetrical. Numbers 1, 2 and 3 in the accompanying drawing respectively indicate an outer ring, an intermediate rolling element, e.g. a cylindrical roller, and an inner ring of a rolling bearing 4, which must be adequately protected against external pollutants, and sufficiently sealed to retain the lubricant inserted during manufacture. Rollers 2 are maintained equally spaced by a retainer 6; and, in the following description, it is assumed, without limiting the scope of the present invention, that outer ring 1 is stationary and inner ring 3 rotary. According to the present invention, the sealing ring 7 comprises an annular metal armature 8 in turn comprising a flat radial portion 9 interposed between two bent end portions 10 and 12 for increasing the rigidity of armature 8. An elastomeric rubber element 14 is cured by co-molding on to armature 8, predominantly on to the surface of armature 8 facing inwards of the bearing, i.e. facing rollers 2. Rubber element 14 is annular, and comprises, at the outer edge, a thick annular rib 16, which is forced elastically inside an annular groove 17 formed close to the edge 18 of outer ring 1 of bearing 4 and open on the side facing inner ring 3, so that sealing ring 7 is secured by friction to stationary outer ring 1. On the outer side (to the right in the drawing), rib 16 presents a radial projection 20 cooperating with a corresponding radial projection 22 on edge 18 to form an annular labyrinth conduit 23 and provide for improved sealing between ring 7 and outer ring 1 of bearing 4. To support and strengthen rib 16 and radial projection 20, armature 8 is bent roughly 180° outwards of bearing 4 to form an axial bead 24. On the smaller-radius side facing inner ring 3 of bearing 4, sealing ring 7 comprises a circular sealing lip 25 bent elastically away from rollers 2 and interference-fitted to a cylindrical surface 26 of inner ring 3; and lip 25 is associated with an inner radial projection 27 separated by a small radial clearance from surface 26 of inner ring 3 to form a labyrinth seal next 10 conduit 28, the dynamic effect of the air in which provides for improved sealing by lip 25 as inner ring 3 rotates. A further projection 29, connected continuously to and radially opposite projection 27, is located, with little and approximately no interference, adjacent to an annular centrifugal element 30 force-fitted integral with inner ring 3 of bearing 4 and on the opposite side of sealing ring 7 to rollers 2. Centrifugal element 30 comprises a metal ring lying substantially in a radial plane and in turn comprising a cylindrical portion 31 fitted to surface 26 of inner ring 3 and connected in one piece to a portion 32, which cooperates with further projection 29, slopes towards rollers 2, and terminates with a portion 33 sloping the opposite way, outwards of bearing 4. Further projection 29 performs two functions: firstly, it prevents the entry of large particles of pollutant substances when bearing 4 is stationary; and, secondly, by virtue of the centrifugal action of element 30, it provides for expelling any small particles (dust) or liquid from the region adjacent to labyrinth 28 as inner ring 3 rotates.

Claims: A sealed rolling bearing (4) comprising a fixed ring (1), a rotary ring (3), intermediate roller elements (2), a sealing ring (7) and a centrifugal element (30) rotating which is integral with said rotary ring (3); said sealing ring (7) comprising a metal armature (8) and an elastomeric element (14), which is cured on to the armature (8) and presents an outer peripheral supporting rib (16) inserted and secured angularly by friction inside a seat (17) on said fixed ring (1), and at least one annular sealing lip (25) interference-fitted with a small amount of friction to a cylindrical surface (26) of said rotary ring (3); said centrifugal element (30) being located relative said sealing ring (7) axially outwardly opposite to said roller elements (2) and comprising a sloped portion (32) which slopes towards said roller elements (2); wherein said sealing lip (25) is associated with a first radial projection (27) of said elastomeric element (14) facing said cylindrical surface (26) to form an annular labyrinth seal, and wherein a further radial projection (29) of said elastomeric element (14) cooperates with said centrifugal element (30), said first radial projection (27) is relative to said sealing lip (25) located axially outwardly on the opposite side to said roller elements (2), and in that said further radial projection (29) is connected continuously to and radially opposite said first radial projection (27) and cooperates with said sloped portion (32) of said centrifugal element (30) such that said annular sealing lip (25) and said further radial projection (29) form between them two conduits separated by said first radial projection (27). A bearing as claimed in Claim 1, characterized in that said rib (16) comprises a radial projection (20) facing a corresponding radial edge (22) of said fixed ring (1); said rib (16) and said radial projection (20) being supported by a bead (24) of said armature (8) bent roughly 90° in relation to a radial portion (9) of said armature (8) and extending axially outwards of said bearing. A bearing as claimed in Claim 1 or 2, characterized in that said centrifugal element (30) comprises a cylindrical portion (31) fitted to said cylindrical surface (26) and connected in one piece to said sloped portion (32) sloping towards said roller elements (2), and a further portion (33) sloping the opposite way, outwards of said bearing.

Inventors: GIROMELLA GIOVANNI, VISCONTI ALBERTO, GIROMELLA, GIOVANNI, VISCONTI, ALBERTO
Applicants: RFT SPA, RFT S.P.A.
Application year: 1996
Main classification: F16C33
IPC codes: F16C33