GB2171156A

GB2171156A - An elastic sealing ring and a bearing outer race ring

Info

Publication number: GB2171156A
Application number: GB08603305A
Authority: GB
Inventors: Stig Hallerback
Original assignee: SKF AB
Current assignee: SKF AB
Priority date: 1985-02-14
Filing date: 1986-02-11
Publication date: 1986-08-20
Also published as: SE8500689D0; JPH0222245B2; FR2577635B1; JPS61189319A; GB8603305D0; FR2577635A1; SE8500689L; DE3603420A1; SE450653B; GB2171156B; IT8619387A0; IT1204792B; DE3603420C2

Abstract

The most favourable operating temperature for a rolling bearing is obtained when the minimum of lubricant necessary to ensure reliable lubrication is used. Leakage is a major problem with small flow rates of lubricant. To reduce the rate of leakage of lubricant, an elastic sealing ring 18 for use with a bearing is of open channel section with the side portions 20 of the channel extending radially inwardly. A bearing outer race ring 15 has an annular groove 16 and at least one radial through bore 17. The elastic sealing 18 is disposed in the groove 16. <IMAGE>

Description

SPECIFICATION An elastic sealing ring and a bearing outer race ring This invention is concerned with an elastic sealing ring which is for use with a bearing outer race ring, and a combination of the two.

Bearings and especially rolling bearings must be lubricated to prevent inter-metallic contact between the rolling elements, raceways and cage and also to protect the bearing against corrosion and wear.

When properly lubricated a film of lubricant is established between the various components of a bearing so preventing inter-metallic contact.

The most favourable operating temperature for a rolling bearing is obtained when the minimum of lubricant necessary to ensure reliable lubrication is used. Too much lubricant constitutes a resistance to movement leading to an increase in temperature.

However, the quantity used also depends on the additional functions which are required of the lubricant, for example, sealing or cooling.

Some bearings are supplied lubricated-for-life, for example, small deep groove ball bearings filled with grease; other bearings which are lubricated with grease require re-lubrication. Oil lubrication of bearings can be achieved by means of an oil bath (which requires a lubricant change at certain intervals), by oil jets or by oil mist.

Attempts have been made to reduce the volume of oil used for lubrication whilst maintaining an oil film between the bearing component. In one example, a rolling bearing having an outer diameter of 200 mm was lubricated with oil at the rate of 3 mm3/min (3 micro litres (3 x 10-6 litres) per minute). Further reductions in the rate of of supply to, for example, the range of 1 mm3/min are being attempted.

A problem that arises with such small rates of supply is that of leakage. Consider for example a rolling bearing mounted in a two-part housing, the housing having a bore for supplying oil to a groove which is located in the outer surface of the bearing.

Leakage will not only occur between the surfaces of the housing and bearing but also between the surfaces of the two parts of the housing, particularly as the groove extends past the join of the two parts ofthe housing.

The invention provides an elastic sealing ring of open channel section with side portions of the channel extending radially inwardly.

Preferably, the ring has means allowing lubricant to pass radially inwardly into the open channel; the means includes a plurality of openings in the base of the open channel; and there are an odd number of openings which are evenly spaced from one another circumferentially.

The invention also provides, in combination, a bearing outer race ring having an annular groove, which is located in its outer circumferential surface, and at least one bore extending radially through the race ring and opening into the groove for the passage of lubricant, and an elastic sealing according to the invention which is disposed in the annular groove.

Preferably, the inner diameter of the sealing ring, in its relaxed state, is less than the diameter of the base of the annular groove.

The sealing ring may be of plastics or rubber.

Further, the invention provides an assembly comprising a housing having a bore and a combination according to the invention which is disposed in the bore, the housing having means for supply lubricant to the bore.

Also, the invention provides a method of preventing leakage of lubricant in an assembly comprising a housing having a bore and a bearing outer race ring which is disposed in the bore, the bearing outer race ring having an annular groove, which is located in its outer circumferential surface, and at least one bore extending radially through the race ring and opening into the groove for the passage of lubricant, the method comprising providing an elastic sealing ring of open channel section with the side portions of the channel extending radially inwardly, and disposing the sealing ring in the annular groove.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, of which: Figure 1 is a part of a perspective view of a spherical roller bearing outer race ring which is mounted in a plummer block housing, the housing being shown only in outline; Figure 2 is part of a longitudinal vertical section with a sealing ring according to the invention which is disposed in the groove in the outer race ring; and Figure 3 is part of a cross section also showing the sealing ring which is in position in the groove.

Figure 1 shows a horizontially split plummer block housing 10 comprising upper and lower halves (cap and base) 11 and 12 respectively which are secured together by two cap bolts 13only one of which is shown. The upper half 11 of the plummer block housing 10 has at the top a drilled radially and vertically extending through bore 14 with a screw fitting for connection to a supply of lubricant.

Positioned in the bore of the housing 10 is a spherical roller bearing of which only the outer race ring 15 is shown for reasons of clarity. The outer race ring 15 has a sphered inner surface, an annular groove 16, which is located in its outercircumferen- tial surface, and three lubrication bores 17 extending radially through the race ring and opening into the groove. The bore 14 in the housing 10 is aligned with the groove 16 in the outer race ring 15 so that lubricating oil can pass through the bore 14, into the groove 16 and through the bores 17 into the interior of the bearing.

With such an arrangement as shown in Figure 1, there are a number of leakage paths by which lubricant can be lost after it passes through the bore 14 and before it reaches the bearing: one path extends axially between the curved surfaces of the outer race ring 15 and the bore of the housing 10; another path extends generally radially outwardly between the horimntal mating surfaces of the two halves 11 and 12 and also through the bolt holes of the cap bolts 13; and a further path extends axially along a groove in the bore of the housing 10 where the two halves 11 and 12 meet. The size of this groove will depend on how well the housing is made, for example, how accurately the burrs have been filed off the two halves when they are removed from the moulds.

Figures 2 and 3 show an elastic sealing ring which is of rubber and is disposed in the annular groove 16 in the outer race ring 15. This sealing ring 18 is of open channel section with a slightly inwardly domed base 19 and radially inwardly extending side portions 20. The base 19 has eleven openings 21 evenly spaced from one another circumferentially to allow lubricating oil to pass radially inwardly into the open channel of the sealing ring 18 and the groove 16 of the outer race ring 15. The lubricant then can travel along the groove 16 and through the bores 17 in the outer race ring 15. The inner diameter of the sealing ring 18, in its relaxed state, is less than the diameter of the base of the annular groove 16 so that the sealing ring is firmly located in the groove.Further when the sealing ring 18 is located in the annular groove 16, it is elastically deformed so that it firmly engages the sides and base of the groove forming an effective seal therewith. Also, the outer diameter of the sealing 18, when located in the annular groove 16 but before the race ring 15 and the sealing ring 18 are mounted in the housing 10, is greater than the outer diameter of the race ring 15 and greater than the bore diameter of the housing. This means that the sealing ring 18 protrudes from the groove 16 and, when the race ring 15 and sealing ring 18 are mounted in the housing 10, it is elastically compressed by the bore surface of the housing so forming an effective seal therewith.

In order for the bearing to receive lubricant, one of the openings 21 in the sealing ring 18 must be aligned with or close to the bore 14 of the housing 10. The sealing ring 18will not remain in the same position during the lifetime of the bearing. Therefore, there must be a plurality of openings 21 and of a number great enough so that there will always be an opening aligned with or close enough to the bore 14 for the lubricant to pan through. The actual number and therefore the relative positions of the openings 21 must also be carefully chosen so that when lubricant is passing through an opening 21 which is positioned at the top of the housing, there is not an opening 21 adjacent to where the two halves 11 and 12 of the housing 10 meet. This can be achieved with an odd number of openings 21.

Preferably, the number N of openings can be expressed as N = 3 + 4K where K is an integer, so that N is a series starting 3, 7, 11 The openings 21 can be replaced by slits in the sealing 18 which, underthe pressure of incoming lubricant, open up and allow the lubricant to pass through.

In another modification, the sealing ring 18 can have openings with flaps on the inside acting as one way valves so allowing the lubricant in but not out.

This simplifies the number and position of the openings.

Claims

1. An elastic sealing ring of open channel section with the side portions of the channel extending radially inwardly.

2. A ring as claimed in Claim 1, wherein the ring has means allowing lubricant to pass radially inwardly into the open channel.

3. A ring as claimed in Claim 2, wherein the means includes a plurality of openings in the base of the open channel.

4. A ring as claimed in Claim 3, wherein there are an odd number of openings which are evenly spaced from one another circumferentially.

5. An elastic sealing ring substantially as herein described with reference to and as shown in the accompanying drawings.

6. In combination, a bearing outer race ring having an annular groove, which is located in its outer circumferential surface, and at least one bore extending radially through the race ring and opening into the groove for the passage of lubricant, and an elastic sealing ring as claimed in any preceding claim which is disposed in the annular groove.

7. A combination as claimed in Claim 6, wherein the inner diameter of the sealing ring, in its relaxed state, is less than the diameter of the base of the annular groove.

8. In combination, a bearing outer race ring and an elastic sealing ring substantially as herein described with reference to and as shown in the accompanying drawings.

9. An assembly comprising a housing having a bore and a combination as claimed in Claim 6,7 or 8 which is disposed in the bore, he housing having means for supplying lubricant to the bore.

10. An assembly comprising a housing, a bearing outer race ring and an elastic sealing ring substantially as herein described with reference to and as shown in the accompanying drawings.

11. A method of preventing leakage of lubricant in an assebly comprising a housing having a bore and bearing outer race ring which is disposed in the bore, the bearing outer race ring which is disposed in the bore, the bearing outer race ring having an annular groove, which is located in its outer circumferential surface, and at least one bore extending radially through the race ring and opening into the groove for the passage of lubricant, the method comprising providing an elastic sealing ring of open channel section with the side portions of the channel extending radially inwardly, and disposing the sealing ring in the annular groove.