AU665654B2 - Seals for hub housing of vehicle trailers - Google Patents

Description

P/00/Oi 21/5/91 AUSTALIARegulation 3.2 AUSTRALsA Fotens Act 19904 66565

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: SEAL~S F'OR HUB HOUSING OF VEHICLJE TRAIL~ERS.......

The following statement is a full description of this invention, including the best method of performing it known to me:--

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I. 1 1 ^s 2 The present invention relates to seals for hub housings of vehicle trailers, caravans and the like.

Normally, stub axles supporting hub assemblies are made in a range of diameter sizes varying from about 36mm to about 38.5mm. In order to seal the inner opening of the hub assembly about the stub axle, seals have been made so that the inner circumferential surface of the seal is flexible enough to receive and engage the various stub axle diameter sizes, when pressed into position.

A contemporary method of sealing a hub housing about the stub axle has been to employ a rubber seal and stainless steel wear ring arrangement.

The seal is tightly fitted about the stub axle, and the wear ring is fitted onto the lip or flange of the hub inner opening. The hub is then fitted onto the stub axle so that when secured, the seal and wear ring bear against each Sother.

The method requires a high interference fit between the seal and stub ,I axle. It has been found by the present inventer that, as the seal is pressed into position on the stub axle and the inner circumferential surface of the seal is enlarged to receive the stub axle there is a general movement of S2' 0 rubber radially outwards which results in an increase in the outside diameter of the seal .As the one stainless steel wear ring available is a fixed diameter and there are at least three different stub axle diameter sizes, the same seal when fitted, has a different outside diameter for each stub axle size. This increase in diameter tends to flatten the point seals against the wear ring, particularly when the larger diameter sized stub axles are used. This tends to deprive the seal of sufficient lubricant and with prolonged rotation of the hub assembly about the stub axle and with the heat generated particularly on the wear ring there is a increasing tendency, over time, for the seal to V i sieze against and spin with the hub assembly. This can result in leakage of grease or other lubricantfrom the interior of the hub through the gap which is formed between stub axle and rotating seal, which may lead to contamination of the brakes, springs and axle and cause grease spots on the ground.

According to the invention, there is provided a hub sealing device comprising: an annular rubber seal, the seal having an inner resilient portion adapted to receive and resiliently engage ay, o r c se.lect~ rcoune o9 cdke.ret cMve.kr sV-Lb De.s an outer resilient sealing portion adapted to co-operate with a hub which rotates relative to the axle and the seal; and an isolating means in the form of a generally non-deformable collar member generally interposed between the inner and outer portions and adapted to substantially isolate any resilient deformation of the inner portion from affecting a pre-set outside dimension of the outer sealing portion".

S2 The seal will thus have a high interference fit on all common sized SIr stub axles.The diameter of the outer circumferential surface including point seals will not enlarge, thus allowing designed point seal profile to be made with the standard stainless steel wear ring.

Particular embodiments of the present invention will now be described with reference to the accompanying drawingsin which:- Fig. 1. is a sectional veiw of a cut-away portion of a preferred seal according to the invention and a cross section of a wear ring into which a preferred seal is fitted, t' v^ (J i 4 Fig is a longitudinal- sectional veiw of a hub housing with wear ring and preferred seal of Fig in place into which is being inserted a stub axle, Fig. 3. is a sectional veiw of a cut away portion of a preferred seal according to the invention and a wear ring into which a preferred seal is fitted, this seal having a alternative collar configuration.

Fig .4 is a sectional veiw of a cut-away portion of a preferred seal according to the invention and a wear ring into which a preferred seal is fitted, this seal having a further alternative collar configuration The following is a description of a preferred embodiment which uses ,1 5 the non-deforming collar member of Fig.I and is described in conjunction with Figs,1 and 2.

The portion of the seal 15 shown in Fig. 1 is part of an annular seal that has an outer circumferential surface 1.6 and an inner circumferential surface 1.The seal 15 is shown abutting the inner surface of an annular wear ring 4 that is mounted on the flange 6 of the inner opening of a hub housing (shown in Fig.2).

The outer circumferential surface 16 includes two interacting point seals 3 and 4 that each abut against spaced location on the wear ring There is also a rounded or blunt point 10 that lightly abuts a radially of a boat trader, caravan or the like, and said vehicle runs over a pothole or comers hub movement due to bearing clearance allows the wear ring 5 to intermittently move away from point 10 allowing lubricant to leak past point

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1 and lubricate point seal 4. When a warm hub is submerged in water, as when launching a boat a negative pressure can exist inside the hub, the recess 12 allows some axicil movement of the whole outer point seal area, and the higher pressure outside the hub exerts an axial force against the point seals 3 and 4 whereby the point seal 10 abuts firmly against the flange of wear ring 5.This increases the overall sealing engagement and more positively prevents water from entering the inside of the hub. The area 11 between point seal 3 and point seal 4. (refer Fig. 1) acts as a lubricant reservoir, said area 11 being filled with lubricant prior to installing a seal 15 in the wear ring 5. The ridge 9 Fig. 1 protrudes past and close to the inner-most rim of the flange of the wear ring 5. The ridge 9 acts as a baffle ,damping pressure waves due to the pumping action of the bearings, whilst spinning in lubricant. The inner circumferential surface 1 of the seal is flexible and is adapted to receive and engage against stub axles of a diameter range between about 36 mm and about 38.5 mm.

The seal 15 includes a non- deformable annular collar member 7 which in S this embodiment is made of steel and is embedded within the seal The collar member 7 has a radial flange portion 17 and an axially extending cylindrical portion 13.

The cylindrical portion 13 extends from proximate one axial end face axially along the seal 15. The annular portion 13 is preferably at least 40% of the axial extent of the seal 15, and more preferably at least The inner circumferential surface of the cylindrical portion 13 prevents an increase or growth in the original as manufactured diameter of the outer circumferential surface 16, when the seal 15 is pressed onto stub axles of a diameter range between about 36mm to about 38.5mm ,thus allowing point seal 3 and point seal 4 to retain designed lip profile and contact tension with the inner surface of wear ring 5. The collar 7 also L I

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ri-Flri+ I 'i i _LLI11~~P~I Sensures a tight shaft seal fit due to the compression of rubber between the inner circumferential surface of the cylindrical portion 13 and the outer circumferential surface of the axle shoulder.

This is achieved by inserting seal 15 into wear ring 5 so that an axial end face of seal 15 "buts against the shoulder of the inner race of the hub inner bearing 25, Then sliding stub axle 26 into the hub cavity, (as shown in Fig. until the forward part of the stub axle shoulder 23 abuts against the other axial end face 24 of the seal 15 and bearing surface 21 engages inner bearing 22, then tightening the nut on the thread of the axle.

Thereby pressing hub 18 towards the axle shaft 19. The seal 15 is forced back by the shoulder of the inner race 25 of the hub inner bearing 22.

The forward part of the stub axle shoulder 23 exerts an opposite force against the edge of the end face 24 of the seal 15, thereby increasing the *Ott seal inner diameter 1 so as to accommodate or expand to the diameter of the I stub axle shoulder During the fitting procedure, force applied at wall 1 Fig. by the stub axle shoulder20 shown as arrows A will pass via the flexable rubber, to the cylindrical portion 13 of the collar 7 and is isolated from the outer surface 16. The annular recess 2 extends from the face 8 in the axial direction past the rim 14 of the cylindrical portion 13 of thecollar 7 and d cooperates to ensure that the expansion is contained in the area between said cylindrical portion 13 of the collar 7 and the shoulder 20 of stub axle 26 and is not deflected to seal point area. That is, force shown as arrows B Fig. 1. causes this portion of seal 15 to expand in the direction of the arrows B. The recess 2 allows room for this expansion, so that force is not transferred to the seal point area above ridge 9.

As a result, the outer circumferential surface 16 of the seal 15 will not grow or increase in diameter when fitted to any of the common sized 7 stub axles with diameters between about 36mm and about38.5mm. Thereby allowing the designed seal lip profile to bear again st and cooperate with the inner surface of the wear ring 5 in the designed manner.

Furthermore, the energy stored between the cylindrical portion 13 of the collar member 7 and the stub axle shoulder 20 ensures a tight seal fit that provides resistance to movement of the seal 15 about the stub axle 26 when the hub 18 is rotating.

The following is a description of the seal 15 shown in Fig.3, which has an alternative collar member to that of Fig.1.

The collar member 7 has a radial flange portion 17 at one end and an axially extended cylindrical portion 13 and is preferably made of steel, the inner circumferential surface of said cylindrical portion 13 opposes forces shown as A in Fig.3. when the seal 15 is engaged on an axle shoulder.

O. The following is a description of a further embodiment of the seal 1 5 which has an alternative collar member 7 shown in Fig.4. This seal Smay replace the seal 15 of Fig.l. and Fig.3.

:i"t CThe collar member 7 is a substantially cylindrical member with a radially outwardly projecting flange at one end and a radially inwardly projecting flange at the other end. The collar 7 extends over the full axial i 20 extent of the seal 15, and is preferably made of steel. The inner circumferential surface shown as 13) Fig.4. opposes forces (shown as A) C t It 4 4 Fig.4. when the seal 15 is engaged on an axle shoulder, Various modifications may be made in details of design and construction without departing from the scope or ambit of the invention.