AU2014101071A4 - Self-cleaning labyrinth seal for disc hub bearing - Google Patents

Abstract

The disclosed labyrinth seal for a hub bearing uses an interception chamber (9) formed by the assembly of a rotating housing (3) and a non-rotating labyrinth outer piece (8) to collect particles entering the labyrinth and allow them to drain out an opening (12). The arrangement minimizes the quantity of particles reaching a contact seal (5), which prevents these particles from entering the hub bearing (2). 8Np '

Description

1. SELF-CLEANING LABYRINTH SEAL FOR DISC HUB BEARING Background [0001] Rotating discs used in agricultural applications, such as tilling discs, require strong bearings to withstand the severe loadings encountered in these conditions. The bearings must be well-protected with suitable sealing arrangements to prevent ingress of dust, soil or similar particles which would rapidly destroy the bearing. [0002] The sealing arrangements used are in turn exposed to the same arduous conditions. Unprotected contact seals will fail quickly due to dust getting between the sealing lips and the moving contact surface. Consequently, a form of labyrinth seal is often used to minimize the ingress of dust into the area where the contact seals are located. [0003] Labyrinth seals act by forcing particles or substances to travel a longer and more indirect path through the seal arrangement before they can enter the housing or cavity which is being sealed. However, in very severe conditions eventually particles will build up in the labyrinth area, and will gradually enter the housing or cavity where the contact seal is located. This will then wear at an accelerated rate. [0004] The invention disclosed herein is intended to improve the labyrinth arrangement by incorporating a method by which particles which enter the labyrinth can be collected and then allowed to exit the labyrinth without proceeding further through the labyrinth towards the contact seal. Summary [0005] The sealing arrangement is shown on the attached diagram, which shows a cross section through a rotating hub used for tilling discs. A machined axle (1) holds a heavy-duty bearing (2). The outer ring of this bearing is held in a machined housing (3), which covers one side of the bearing and axle, and incorporates a flange (4) which allows attachment of the disc. The bearing allows the housing to rotate on the axle (1).

2. [0006] On the other side of the bearing is a cavity which houses a contact seal (5). The inner section of this seal is located on the outer surface of a spacer (6), which is non-rotating like the axle (1). The outer section of the seal is pressed into the rotating housing (3). [0007] The spacer (6) is pushed against the bearing (2) by a seal plate (7) and a labyrinth outer piece (8). Both of these components are non-rotating like the spacer and the axle (1). The only path by which particles can enter the cavity in which the seal (5) is housed is through a very small clearance between the seal plate (7) and the housing (3). [0008] The clearances between the non-rotating labyrinth outer piece (8) and the rotating housing (3) are very small, and the outer surface of the housing is machined so that the components fit together to create the labyrinth effect. The path created by this clearance opens out abruptly into a cavity (9) which acts as an interception chamber. At this chamber the labyrinth outer piece (8) is machined at a taper to form a conical surface (10). As the housing rotates, the motion tends to force particles to away from the centre of rotation and they will tend to accumulate at the bottom of the interception chamber. [0009] At the top of the interception chamber (9) there is a close clearance (11) between the labyrinth outer piece (8) and the housing (3) which extends around half the circumference so that the ingress of particles is minimized. At the bottom of the interception chamber, the face of the housing has been cut back slightly to form a drain opening (12), allowing particles accumulating in the interception chamber to exit more easily. [0010] The effect of the arrangement described above is that particles entering the labyrinth through the clearance between the housing (3) and the labyrinth outer piece (8) are captured in the interception chamber (9), and the shape of the surfaces and openings is such that the easiest path for the particles is to exit the chamber through the drain (12) rather than to move further into the labyrinth.

Claims (3)

1. 3. Claims The claims defining the invention are: 1. A labyrinth sealing arrangement for a hub bearing which incorporates an interception chamber with a tapered surface to arrest and collect particles entering the labyrinth. 2. A labyrinth sealing arrangement as claimed in Claim 1, in which the face of the component forming the outer part of the interception chamber is cut back at the bottom to allow easier draining of collected particles. 3. A labyrinth sealing arrangement as claimed in Claim 1, in which a contact seal is installed after the labyrinth to prevent any particles which have moved through the labyrinth from entering the bearing.
2. 4. A labyrinth sealing arrangement as described in Claims 1, 2 and 3 in which the component forming the outer part of the interception chamber is made of a wear-resistant plastic.
3. 5. A labyrinth sealing arrangement as described in Claims 1, 2 and 3 in which the component forming the outer part of the interception chamber is made of a metal, such as steel.