GB2130310A

GB2130310A - Seal assembly consisting of at least one sliding lip

Info

Publication number: GB2130310A
Application number: GB08327894A
Authority: GB
Inventors: Franco Colanzi; Angelo Vignotto
Original assignee: RIV SKF Officine di Villar Perosa SpA; RIV Officine di Villar Perosa SpA
Current assignee: SKF Industrie SpA
Priority date: 1982-10-19
Filing date: 1983-10-18
Publication date: 1984-05-31
Also published as: IT8253828V0; ES275074Y; FR2534654A1; SE8305624D0; GB8327894D0; GB2130310B; ES275074U; SE8305624L

Abstract

A seal assembly (9) consists of two rigid shields (13, 14) designed for assembly on two relatively rotatable parts (5, 6), one shields (13) being provided with at least one flexible round sealing lip (23, 24) and the other (14) with at least one sliding face (29, 30) for the said lip(s) (23, 24) with which the latter engage(s) to produce a sliding sealing arrangement. The seal assembly (9) also consists of means (34, 35) for watertight connecting the said two shields (13, 14) together so as to form a single unit. The lip 24 may be provided with a pressure relieving slot (Fig. 3). When only a single lip 24 is present (Fig. 4, 5) it may be spring loaded into co-operation with its associated surface (Fig. 5). <IMAGE>

Description

SPECIFICATION Seal assembly consisting of at least one sliding lip The present invention relates to a seal assembly, consisting of at least one sliding lip, designed for assembly between two parts with a relative surface speed inbetween, so as to provide for an essentially airtight seal.

Seal assemblies of various types already exist for sealing between two mutually rotating parts, such as the internal and external rings of a ball bearing or a rotary shaft and its carrier. Particularly good, cheap seal assemblies are those consisting of two face-to-face rigid metal shields, each fitted on to one of the rotary parts involved, and one of which consists of one or more flexible rubber lips for sealing against sliding faces on the other shield facing it.

Between the two shields, provision is made for a small preset amount of radial slack to provide additional labyrinth sealing.

The seal assembly described is not without drawbacks, however. The major one consists in the fact that a round chamber exists between the two facing shields for containing grease for lubricating the lips or one of them (the axial one) if the seal assembly is a two-lip type (radial and axial) as described in Italian Patent Application n.68665 A/80 filed by the present Applicant and the content of which is incorporated herein for reference purposes where required. External pollutants, particularly water or damp, could infiltrate inside the said chamber through the said labyrinth seal, which obviously is not airtight, despite the centrifugal action exerted by turning of the outermost shield, and so collect inside the chamber and come into long-term contact with the sealing lip/s.In time, such contact with pollutants or water hardens the rubber lips so as to reduce or eliminate sealing efficiency altogether. What is more, as the two shields have to be assembled separately on to the rotary parts and then mated so as to bring the lips on one of the shields into contact with the sliding faces on the other, the known type of seal assembly described involves accurate assembly in two stages.

The aim of the present invention is to provide a seal assembly of the type described but without the aforementioned drawbacks, in particular, a seal assembly on which the lubricating grease chamber is airtight and which can be assembled in one operation.

With these aims in view, the present invention relates to a seal assembly, designed to fit between two parts with a relative surface speed in between, so as to provide for an essentially airtight seal between them; the said assembly consisting of two round, rigid shields, arranged facing each other and provided with means for assembling each of the said shields at an angle to and integral with one of the said parts, the first of the said shields being provided with at least one flexible round sealing lip extending towards the second of the said shields and the latter consisting of at least one round sliding face for the said sealing lip which engages with the said face so as to exert a pre-established pressure on it; characterised by the fact that means are provided for watertight connecting the said first and second shields together, while at the same time allowing them to rotate, and that the said means bind the said first shield firmly on to the said second shield.

A number of arrangements of the present invention will now be described, by way on non-limiting examples, with reference to the attached drawings, in which: Figure 1 shows a partial cross section of a bearing fitted with the seal assembly according to the present invention; Figure 2 shows a larger scale detail of Fig.

1; Figures 3 and 4 show two variations of the Fig. 1 and 2 seal assemblies respectively.

Number 1 in Fig. 1 indicates an oblique double-row ball bearing, only half of which is shown for the sake of simplicity, fitted between a shaft (2) and seat (3) on a carrier (4).

Bearing 1 consists of an internal (5) and external (6) ring, between which roll balls 7, and a retainer (8) also for the said balls 7. As shown more clearly in Fig. 2, a seal assembly (9) is fitted between rings 5 and 6 for watertight sealing a round chamber located between rings 5 and 6 and containing balls 7, so as to protect the said balls and their respective raceways (11, 1 2) from external pollutants, such as water, dust or damp.

Seal assembly 9 (Fig. 2) consists of two round, rigid metal shields (13, 14) assembled facing each other and each forming one with a respective cylindrical coupling (15, 16) designed to fit in seats on rings 6 and 5 so as to fit shield 1 3 at an angle to and integral with ring 6 and shield 14 to ring 5. Couplings 1 5 and 1 6 and shields 1 3 and 14 are coaxial, concentric and preferably made of steel. Shields 1 3 and 14 are essentially flat and perpendicular to side walls 1 8 and 1 9 and couplings 1 5 and 1 6 respectively.Shield 1 3 has a round centre boss (20), for reducing the overall axial dimension of assembly 1 by following the outline of balls 7, and a centre bore (21) in which one end (22) of coupling 1 6 is fitted coaxially with ample radial slack.

Sheild 1 3 is also provided with two round sealing lips (23, 24), made of flexible material, e.g. rubber, and secured integral to it.

Lips 23 and 24 form one with a round rubber component (25) vulcanized and/or bonded straight on to front face 26 of shield 3 and internal face 27 of coupling 1 5 facing shield 14.

At a common round root section (28) round the edge of bore 21, lips 23 and 24 branch off; lip 23 axially, parallel to the axis of coupling 16 in the direction of shield 14, and lip 24 radially, perpendicular to the axis of coupling 16, thus making lips 23 and 24 essentially perpendicular to each other.

Shield 14 is provided with a flat, round front sliding face (29) and coupling 1 6 with an external cylindrical sliding face (30), both faces being arranged facing shield 1 3.

Lips 23 and 24 are of such a length as to interfere with and be flexed by shield 14 and coupling 16, while ends 31 and 32 exert a preset pressure on sliding surfaces 29 and 30 respectively. Ends 31 and 32 are also designed to slide with very little friction over faces 29 and 30 when shields 1 3 and 14 shift at an angle to and integral with rings 5 and 6 between which a relative surface speed obviously exists during operation. Consequently, lips 23 and 24 exert an essentially airtight sliding seal on faces 29 and 30 thus preventing pollutants from entering chamber 10 or lubricant from leaking from it. What is more, as lips 23 and 24 exert a different type of seal, 23 axially and 24 radially, chamber 10 is also rendered watertight even under any form of direct operating strain.

Shield 14 is provided with a round, radially external, essentially tapered edge (33) extending in the direction of shield 1 3 and obtained by bending shield 14 itself. Edge 33 has a tapered shoulder face (34), facing the opposite way to shield 13, with which a round, essentially radial lip (35) at an angle to and integral with shield 1 3 engages via coupling 1 5. Lip 35 forms one piece with part 25 and, consequently, also lips 23 and 24, and extends radially towards the axis of coupling 1 6 from edge 36 on coupling 1 5. Lip 35 is flexible and of such a length as to interfere with and be flexed by edge 33, while one end (37) exertes a preset pressure on face 34.Lip 35 also engages with face 34 and edge 33 to prevent shields 1 3 and 14, arranged facing each other, from parting axially and so keep them coaxial. Consequently, lip 35 and face 34 provide for watertight connection and, at the same time, mutual rotation of shields 1 3 and 14 which are helf together firmly so as to form a seal assembly (9) of one structural unit which can be assembled on and taken off bearing I in one single operation.

Furthermore, during the manufacture of seal assembly 9, the flexibility of lip 35 provides for easy assembly of shield 1 3 on to shield 14 by flexing under the pressure of edge 33 and springing back to engage with it and so prevent any possibility of shields 1 3 and 14 coming apart.

Shields 13 and 14 and their respective integral couplings 1 5 and 1 6 combine to form a round chamber (38) which is kept essentially watertight by radial sealing lip 24 and lip 35 which engage respectively with faces 30 and 34. Chamber 38, which is designed to be filled partially with lubricating grease to improve and lubricate the connection between ends 31 and 32 and faces 29 and 30, houses axial seating lip 23 which is thus fully isolated from external pollutants both on the side of chamber 10, thanks to lip 24, and on the opposite side, thanks to lip 35. Edge 33 also has a radially external end (39), essentially perpendicular to the axis of coupling 15, with a sharp edge (40) for centrifuging any pollutants managing to penetrate through the seal of lip 35 on coupling 15, so as to provide further protection for lip 23.The special shape of end 37 on lip 35 also provides for centrifuging pollutants outside chamber 38.

Fig. 3 shows a variation (41) of seal assembly 9 from which it differs only in a few small details. Parts similar or identical to those already described are shown with the same numbers.

Seal assembly 41 is provided with an essentially flat shield (13a) without the boss (20) on shield 1 3. This design increases the overall axial dimension of the seal assembly (41) but is cheaper to make and can be used where no space problems are involved, e.g.

on shafts instead of bearings.

Furthermore, lip 24 is provided with at least one hole or through slot (42) for relieving any excess working pressure forming inside the chamber protected by seal assembly 41 This is not a new detail, however. Finally, end 37a on lip 35 is shaped slightly differently and perpendicular to wall 1 8.

Fig. 4 shows a seal assembly (43) which differs from assembly 9 in Fig. 2 solely in the shape of end 37a on lip 35 and the fact that it has no axial lip 23. Parts similar or idential to those already described are shown with the same numbers. Owing to the absence of lip 23, the overall axial dimension can be further reduced as compared with seal assembly 9 with no reduction in sealing efficiency thanks to the provision of lip 35. The latter also protects lip 24 from external pollutants which could otherwise penetrate inside chamber 38.

Fig. 5 shows a variation (44) of seal assembly 43 from which it differs solely in the design of sealing lip 24a which differs from lip 24. Parts similar or identical to those already described are shown with the same numbers. Lip 24a is U-shaped in that end 32, instead of engaging with face 30, is bent 180 towards root section 28, thus forming on lip 24a a round seat (45) for a round pressure spring (46) for exerting a preset pressure and forcing a round intermediate section (47) of lip 24a, roughly located at the bend of end 32, against face 30 so as to engage with and exert a sliding seal on it. In a preferred known arrangement, seat 45 is offcentered in relation to sealing section 47 so as to provide for improved sealing performance.For obtaining lip 24a more easily, part 25 preferably embraces the whole of shield 1 3 so as to cover, besides faces 26 and 27 also an external side face (48) on coupling 19 and a front face (49) on shield 1 3 opposite face 26. This arrangement provides for better corrosionproofing of shield 1 3 and a firmer fit of the overall assembly or unit (44) in the sealing seat. The advantages of the present invention will be clear from the description given. Firstly, it provides for making dualshield, sliding-lip seal assemblies whose parts are held firmly and permanently together so as to form preassembled units that can be mounted on operating parts in one single operation, preferably on a press, thus halving both the time and cost currently required for assembling similar seal assemblies. Secondly, the chamber between the shields on the seal assembly is completely airtight which prevents pollution of the lubricating grease inside and, above all, damage to the sealing lip/s.

To those skilled in the art is will be clear that changes can be made to the seal assembly described by way on a non-limiting example without, however, departing from the scope of the present invention.

Claims

1. Seal assembly, designed to fit between two parts with a relative surface speed inbetween, so as to provide for an essentially airtight seal between them; the said assembly consisting of two round, rigid shields, arranged facing each other and provided with means for assembling each of the said shields at an angle to and integral with one of the said parts; the first of the said shields being provided with at least one flexible round sealing lip extending towards the second of the said shields and the latter consisting of at least one round sliding face for the said sealing lip which engages with the said face so as to exert a pre-established pressure on it; characterised by the fact that means are provided for watertight connecting the said first and second. shields together, while at the same time allowing them to rotate, and that the said means bind the said first shield firmly on to the said second shield.

2. Seal assembly according to Claim 1, characterised by the fact that the said means for connecting together the said shields consist of a tapered shoulder face one one of the said shields and a second flexible round lip integral with the second of the said shields; the said second lip exerting a preset pressure on the said tapered face and engaging with it so as to prevent the said round shields from separating axially and to keep them coaxial with each other.

3. Seal assembly according to Claim 2, characterised by the fact that the said forst shield is provided with the said second lip extending essentially radially towards the axis of the said first shield; the said second shield having a round tapered edge extending towards the said first shield; the said tapered shoulder face being on the said tapered edge facing the opposite way to the said first shield.

4. Seal assembly according to any of the previous Claims, characterised by the fact that the said sliding face is arranged facing the said first shield, the said sealing lip being provided with at least one through hole.

5. Seal assembly according to any of the previous Claims, characterised by the fact that the said means for assembling the said shields on to the said parts consist of a first and second concentric coupling forming one respectively with the said first and second shield so as to fit into respective seats on the said parts.

6. Seal assembly according to Claim 5, characterised by the fact that the said first shield is provided with two sealing lips, one radial directed towards the axis of the said first shield and engaging with an external face on the said second coupling, and one axial, essentially parallel to the axis of the said first shield, directed towards the second shield and engaging with a flat front face on the latter facing the said first shield; the said second lip extending from an internal face on the said first coupling.

7. Seal assembly according to any of the previous Claims from 2 to 6, characterised by the fact that the said second lim and the said sealing lip form one with a round rubber part vulcanized straight on to a face of the said first shield facing the said second shield.

8. Seal assembly according to any of the previous Claims from 5 to 7, characterised by the fact that the said round tapered edge has a radially external end essentially perpendicular to the axis of the said second shield with a sharp edge for centrifuging any pollutant substances towards the said first coupling.

9. Seal assembly according to any of the previous Claims from 6 to 8, characterised by the fact that the said shields and the said couplings combine to form a round chamber sealed essentially water-tight by the said second lip and the said radial lip, the said axial lip being housed inside the said chamber which is designed to be filled partially with grease.

1 0. Seal assembly as described and shown on the attached drawings.