AU613271B2

AU613271B2 - Improved labyrinth seal assembly

Info

Publication number: AU613271B2
Application number: AU56167/90A
Authority: AU
Inventors: Jorg Balzer
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-10-18
Filing date: 1990-06-01
Publication date: 1991-07-25
Anticipated expiration: 2010-06-01
Also published as: AU5616790A

Description

61327 COMMONWEALTH OF AUSTRALIA The Patents Act 1952-1969 Name of Applicant(s): ROLF FRANZ HORST SIEDENTOPF Address of Applicant(s): 6 Shoalhaven Avenue SPRINGWOOD QLD 4127 Address for Service: CULLEN CO., Patent Trade Mark Attorneys, 240 Queen Street, Brisbane, Qld. 4000, Australia.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: IMPROVED LABYRINTH SEAL ASSEMBLY The following statement is a full description of the invention including the best method of performing it known to us I i ~u 2 THIS INVENTION is directed to an improved labyrinth seal and in particular to an improved labyrinth seal for roller bearings.

Labyrinth seals are generally superior to other types of seals in excluding contaminants such as dust and moisture from bearing assemblies.

The seals are particularly suited to protect bearings during high speed operations. Under such conditions the bearings liberate a considerable amount of heat and this results in a pressure rise within the bearing housing.

Labyrinth Pcals are capable of dissipating the pressure rise without appreciable loss of sealing properties.

A particu-ar use for labyrinth seals is to seal roller bearings on conveyor belt rollers. In the mining industry, excavated ore is usually transported from the excavation site to a storage or treatment site along a conveyor belt which can be many kilometres long. The conveyor belt is supported by many hundreds or thousands of rollers and these rollers are subjected to high rates of rotation.

It is important that the bearings in these rollers are protected from contamination by ore dust, water etc, to minimise seizure of the bearings.

Australian patent application 33800/78 discloses a seal assembly comprising a number of annular seals fitted to a shaft or housing. The seals are generally shaped in 3 configuration and when assembled, define a substantially sinuous pathway between the bearing housing and the exterior of the roller barrel. The pathway defined by the seals still allows appreciably contamination of the bearing housing by dust and moisture.

Australian patent application 21089/88 discloses a labyrinth seal assembly comprising a number of annular seals fitting to a shaft and housing. The seals when fitted again define a substantially sinuous pathway between the bearing housing and the exterior of the roller barrel. Dust and moisture is still able to enter into the seal assembly at undesirable levels.

Australian patent application 16142/83 attempts to overcome the disadvantages of using a number of annular "L" shaped seals as disclosed in applicants 33800/78. The application describes the use of a brush located between two adjacent seals. The brush improves the sealing properties of the assembly while still accommodating changes in pressure.

The brush is prone to wear and tear and clogging by contaminants.

Australian patent application 29570/84 discloses a rotary shaft seal including a replaceable wear sleeve cartrage. The seal is complex and expensive to manufacture and is prone to wear.

It is an object of the invention to provide an improved labyrinth seal assembly defining an internal pathway which improves. sealing characteristics and which still accommodate variations in pressure.

In one form the invention resides in a labyrinth seal assembly for sealing a bearing between two relatively rotatable co-axial members, said seal assembly comprising a first annular portion mounted relative to one of the co-axial members and extending at right angles therefrom, at least one second portion mounted to and extending at right angles from said first annular portion, a third annular portion mounted relative to the other of the co-axial members and extending at right angles therefrom, at least one fourth portion mounted to and extending at right angles from said third annular portion, at least one of said second and fourth portions being in a spaced partially overlapping -configuration, and a fifth annular portion mounted relative to one of the co-axial members and extending to adjacent the other of the co-axial members, said first to said fourth portions being located axially between said fifth annular portion and the bearing, and defining a fluid pathway between said bearing and the exterior of the seal assembly.

The labyrinth seal assembly may be used to seal a bearing mounted between a shaft and a roller body. The shaft and roller body may form part of a conveyor roller.

L The roller body may include a recessed portion having an inner wall extending around the shaft and into which the bearing and the improved labyrinth seal of the invention can be fitted.

The first annular portion may be mounted to the shaft or roller body but preferably is mounted to the shaft.

The first annular portion may be integral with a first bush which is fitted around the shaft. Alternatively, the first annular portion can be formed separately from the bush and i0 subsequently fitted thereto.

The first bush may function to locate or fix the bearing onto the shaft. Alternatively, the bearing may be fitted by means of a circlip or other known fitting techniques.

The first annular portion preferably extends outwardly at right angles relative to the longitudinal axis of the shaft. The first annular portion may extend to a position adjacent to but spaced from the inner wall of the housing.

The one or more second portions may extend outwardly from the first annular portion at substantially right angles. If more than one second portion is present it is preferred that they all extend in the same direction and are of the same length although it is possible for some to extend in the opposite direction.

It is preferred that the labyrinth seal assembly is 1. -1

A

provided with a pair of spaced second portions extending perpendicularly with respect to the first annular portion and in the same direction to form a seal having a "F" configuration.

The third annular portion is mounted to or adjacent the shaft or roller body which does not support the first annular portion. Thus, the third annular portion may be mounted to the inner wall of the recessed portion. The third annular portion may be integrally formed with a second bush which is mounted to the inner wall of the recessed portion.

Alternatively, the third annular portion may be separate from and mountable to the second Dush.

The second bush may abut against the bearing housing to locate or fix the bearing against axial movement along the shaft.

The third annular portion is provided with one or more fourth portions which preferably extend outwardly from the third portion at approximately right angles. A plurality of fourth portions may be provided although it is preferred that a pair of spaced fourth portions are provided which extend in the same direction to that referred to above and are of the same length. The third and fourth portions may in combination form a seal having an configuration.

The first, second, third and fourth portions are oriented relative to each other so that at least some of the second and fourth portions are in a spaced and partially 7 overlapping orientation. Thus, one or more and preferably all the second portions may be directed towards but spaced from the third annular portion while one or more and preferably all of the fourth portions are directed towards but spaced from the first annular portion. This orientation results in the formation of a torturous pathway between the bearing and the exterior of the housing.

The fifth annular portion may be mounted to the first or second bush and may extend therefrom to a position adjacent to but spaced from the face of the opposed bush.

Preferably, the fifth annular portion is integrally for, d with the second bush. The fifth annular portion can be of any desired shape and preferably comprises a stepped configuration.

The labyrinth seal assembly of the invention may further include an end cap or flinger. The end cap or flinger may be mounted to either the shaft or housing and may include a lip which is in sliding contact or closely spaced from a portion of the fifth portion thereby protecting the labyrinth seal from ingress of foreign material such as dirt or moisture. Preferably, the end cap or flinger is mounted to the shaft.

The invention will be better understood by reference to the following description of one preferred embodiment thereof in which: Figure 1 is a side section elevation view of a 8 conveyor roller having an improved labyrinth seal according to the invention.

Figure 1 discloses a conveyor roller comprising a shaft 10 and a roller body 11. The shaft is typically mounted against rotation to a support while the roller body is freely rotatable about the shaft. The roller body has an end face 12 having a recess 13 extending around the shaft and co-axial therewith.

A ball bearing assembly 14 is located at the rear portion of recess 13. The assembly 14 typically comprises an upper and lower race 15, 16 which supports a plurality of ball bearings 17. The upper race 15 is fitted to the inner face 15a of roller body 11 while lower race 16 is fitted to shaft 10. An inner seal 27 is located between the ball bearing assembly and rear portion of recess 13.

A first bush 18 is fitted onto shaft 10. One edge of bush 18 abuts against race 16 to lock the race into position. Bush 18 has an integrally formed first annular portion 19 comprising a perpendicularly extending flange.

The flange extends substantially across the spacing between shaft 10 and inner face 15a of body 11.

The first annular portion 19 is provided with a pair of spaced second portions 20a, 20b which extend perpendicularly from the first annular portion 19. Both portions 20a, 20b are the same length and extend in the same direction with the free ends directed towards the ball 9 bearing assembly 14.

A second bush 21 is fitted to the inner face 15a of body 11. One edge of bush 21 abut against race 15 to lock the ball bearing assembly into place. Bush 21 at this portion is provided with a recess 22 into which is fitted a third annular portion 23. The base portion of the third annular portion also abuts against race The third annular portion 23 comprises a flange which extends perpendicularly from bush 21. Portion 23 extends to a position spaced from the first bush 18.

A pair of spaced fourth portions 24a,24b extend perpendicularly from the third annular portion 23. Both fourth portions extend in the same direction with the free ends extending towards the first annular portion 19.

Portions 20a,20b and 24a,24b are in a spaced overlapping relationship relative to each other.

The third annular portion 23 is located between the first annular portion 19 and the ball bearing assembly 14.

A fifth annular portion 25 is integrally formed with second bush 21 and extends to a position spaced from first bush 18. The fifth annular portion 25 comprises a flange having a stepped configuration.

The fifth annular portion 25 is located on bush 21 such that the Ist 4th portions are located axially between the fifth annular portion 25 and the bearing assembly 14.

An end cap of flinger 26 is fitted around shaft m The end cap has an L shaped flange with the free end of which is in sliding contact or closely spaced from the base portion of the fifth annular portion One method of assembly of a roller conveyor having the improved labyrinth seal assembly of the invention is as follows. Ball bearing assembly 14 is initially pressed fitted onto shaft 10 at the rear of the recess 13.

Thereafter, third annular portion 23 is loosely located against upper race 15 and first bush 18 is press-fitted onto shaft 10 with one end face abutting against lower race 16.

Second bush 21 is then press-fitted onto the inner face of roller body 11 with one end abutting against race 15 and also locking third annular portion 23 into position. An end cap or flinger 26 can then be fitted to shaft The labyrinth seal provides an improved pathway between the bearing and exterior of the housing which reduces ingress of solid or liquid contaminants while still accommodating variations in pressure due to heating of the bearings.

The seal aids in the prevention of "wobble" and a subsequent pumping of contaminated grease to the bearing.

Therefore bearing life is extended. The improved labyrinth seal of the invention has a very low roll resistance factor with values of 3.5 Newtons (at start) and 2.6 Newtons (in motion) being observed. Penetration of moisture into the roller either during use or when being hosed down with high ii 11 pressure hoses for cleaning purposes is greatly reduced.

Test results with rollers having the improved labyrinth seal assembly of the invention show that when the rollers were used at full speed (maximum 550rpm) underwater for 96 hours and then left submerged in water for a further 240 hours less than 10 percent showed a very slight emulsion of water in grease.

The bearing and seal is almost 100% maintenance free with no requirement for lubrication ports.

The conveyor roller is quiet in operation with valves of 58dB being observed at a 1.0 metre distance from a conveyor belt advancing at 1.3 m/second.

It should be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit and scope of the invention.

I

Claims

2. The labyrinth seal as claimed in claim i, wherein said first annular portion is mounted to a first bush said bush being mountable relative to one of the co-axial members.
3. The labyrinth seal claimed in claim 2, where said first annular portion comprises a flange extending perpendicularly from said first bush. 13
4. The labyrilLth seal as claimed in claims 2 or 3, wherein said bush is mounted a shaft said shaft comprising one of the co-axial members. The labyrinth seal as claimed in any one of the preceding claims comprising a pair of said second portions.
6. The labyrinth seal as claimed in claim 5, wherein said pair of second portions are of the same length and are in a spaced parallel relationship relative to each other.
7. The labyrinth seal as claimed in any one of the preceding claims, wherein said third annular portion is mountable to a second bush, said bush being mountable relative to one of the co-axial members.
8. The labyrinth seal as claimed in claim 7, wherein said second bush is mounted in a recess in a roller body said body comprising one of the co-axial members.
9. The labyrinth seal as claimed in claims 7 or 8, wherein said third annular portion comprises a flange extending perpendicularly from said second bush. The labyrinth seal as claimed in any one of the preceding claims comprising a pair of fourth portions.
11. The labyrinth seal as claimed in claim 10, wherein said pair of fourth portions are of the same length and are in a spaced parallel relationship relative to each other.
12. The labyrinth seal as claimed in claims 6 and 11, wherein one of said pair of second portions and one of said pair of fourth portions are in a spaced partially overlapping configuration. 14
13. The labyrinth seal as claimed in any one of the preceding claims wherein said fifth annular portion comprises a flange having a stepped configuration.
14. The labyrinth seal as claimed in any one of claims 7 to 13, wherein said fifth annular portion is mounted to said second bush. The labyrinth seal as claimed in any one of the preceding claims comprising an end cap.
16. A roller assembly comprising a shaft, a roller body, a bearing assembly disposed between said shaft and roller body said bearing assembly being protected by a labyrinth seal as claimed in any one of the preceding claims.
17. The roller assembly as claimed in claim 16, wherein said body includes a recessed end face co-axial with said shaft, said recessed end face having an inner wall and an end wall said labyrinth seal being disposed between said shaft and said inner wall, said bearing assembly being disposed between ;d seal and said end wall.
18. A labyrinth seal assembly substantially as hereinbefore described with reference to the accompanying drawings. DATED this Thirtieth day of April, 1991. ROLF FRANZ HORST SIEDENTOPF by his Patent Attorneys CULLEN CO. t4VS r.C r L_ ^2-Uil. CI -I I