WO2019036733A1

WO2019036733A1 - Bearing mount

Info

Publication number: WO2019036733A1
Application number: PCT/ZA2018/050038
Authority: WO
Inventors: Warwick STEINHOBEL
Original assignee: Steinhobel Warwick
Priority date: 2017-08-14
Filing date: 2018-07-03
Publication date: 2019-02-21

Abstract

A bearing mount includes: a cylindrical race member; means for securing the race member against rotation to a shaft; first and second rings; and a cylindrical housing. The cylindrical race member defines: (i) a radially outwards facing surface along which bearing elements revolve; and (ii) a radial inwards facing surface that contacts the shaft. The housing is sized to receive the race member and securing means radially therein while defining an annular gap between: the housing; and the race member and securing means. The first and second rings: are secured to the housing; extend radially inwards of the housing; and are axially spaced from each other greater than the maximum axial dimension of the race member, to extend radially inwards from the housing beyond each axial end of the race member. The first and second rings are made of a material having a hardness less than the hardness of the housing, wherein: A < (B/2) where: A is the minimal radial spacing between: (i) the radial inwards facing surface of the housing on the one hand; and (ii) the radially outwards facing surface of the securing means or race member on the other hand; and B is the difference between: (i) the minimum diameter of the radial inwards facing surface of the housing; and (ii) the minimum diameter of the radial inwards facing surface of the race member.

Description

BEARING MOUNT

BACKGROUND

The present invention relates to a bearing mount. More particularly, the present invention relates to a bearing mount with sacrificial rings fixed against rotation to a bearing housing, 3Ί which sacrificial rings reduce damage to a rotating shaft consequent to bearing failure.

Various bearing assemblies are known. For example:

US 2011/0204734 ^'Motor grounding seal., US5,655,845 ^'Bearing housing seal., ¾ US5,221,095 ^'Static and dynamic shaft seal assembly., EP1396610 ^'Roller bearing with oil ring lubrication_, and WO01/27502 ^'Improved rotary shaft bearing isolator seal_, describe a bearing housing with a sacrificial element rotatably mounted to the housing. In these arrangements, the annular gap between the bearing housing and a rotating shaft is typically closed by a labyrinth seal.

US4,063,786 ^'Self-lubricating auxiliary bearing with a main bearing failure indicator_, describes a runner mounted on a shaft and rotatable relative to a bearing housing. Upon bearing failure, the runner moves radially towards the housing and triggers a bearing failure indicator. A drawback of this arrangement is that the runner is rotatable: ¾ with the shaft; and relative to the housing.

US6,250,813 ^'Bearing assembly with housing cap and seal_, describes a pair of seals extending radially inwards from the housing, towards a shaft. The seals are not intended to rotate with the shaft. A drawback of this arrangement is that the radial spacing t¾ between the housing and the shaft is too small to prevent direct contact between the housing and the shaft consequent to bearing failure.

Furthermore, it is known for brush seals comprising brushes and an associated rub plate to seal annular gaps between a stator and a rotating shaft. Such arrangements are t¾ described in US 2003/0085525 ^'Deformable brush seal support US 2004/0126227 ^'Sea^ EP0453315 ^'Brush seals_, and EP1353097 ^'Brush seal.. However, these seals with rub plates are not described as forming part of a bearing assembly. It is a n object of the present invention to provide a bea ring mount including: a housing; and sacrificial rings (with sea ls) secured against rotation to the housing, whereby bearing failure (a bsent failure of the bearing mount itself) results in wea r of the sacrificia l rings by ¾ a rotating shaft, without permitting direct contact between the rotating shaft and the housing.

S UMMARY OF T H E INVE NTION

3Ί According to a preferred embodiment of the invention, there is provided a bearing mount including: a cylindrical race member defining: (i) a radially outwards facing surface along which, in use, bearing elements revolve; and (ii) a radial inwa rds facing surface that, ¾ in use, contacts a s haft extending axially through the race member; mea ns for, in use, securing the race member against rotation to a shaft extending axially through the race member; tfrl a cylindrica l housing sized a nd shaped, in use, to receive the race member and securing means radially therein while defining an annular gap between: the housing on the one hand; a nd the race member and securing means on the other hand; first and second rings: (i) secured to the housing; (ii) extending radia lly inwards of t¾ the housing; and (iii) axially spaced from each other greater than the maximum axial dimension of the race member, in use, to extend radially inwards from the housing beyond each axial end of the race member; the housing being made of a first material and the first and second rings being t¾ made of a second material having a Moh s hardness less tha n the Moh s hardness of the first material; wherein:

[A] < ([B]/2) where: [A] is the minimal radial spacing, in use, between: (i) the radial inwards facing surface of the housing on the one hand; and (ii) the radially outwards facing surface of the securing means or race member on the other hand; and

[B] is the difference between: (i) the minimum diameter of the radial inwards facing surface of the housing; and (ii) the minimum diameter of the radial inwards facing surface of the race member.

3Ί Typically, the bearing mount further includes: a first sealing element extending radia lly inwards from, and continuously a long the first ring to form a closed loop; and

¾ a second sealing element extending radially inwards from, and continuously along the second ring to form a closed loop.

G enerally, each of the first and second rings together with their corresponding first and second sea ling elements extend radially inwa rds of the housing by at least [A].

P referably, each of the first a nd second rings with corresponding first and second sealing elements extend radia lly inwards from the housing a distance between 90% x ([B]/2) a nd 1 10% x ([B]/2). t¾ Typically, the first and second sealing elements are made of a material that is different to the material of which the first and second rings are made.

G enerally, the material of which the first and second sea ling elements are made is more flexible a nd resilient tha n the material of which the first and second rings a re made.

P referably, the first a nd second sealing elements a re made of felt or Neoprene. Typically, each of the first and second rings is made of a polymeric material.

G enerally, each of the first and second rings is made of Nylon.

P referably, the housing is made of cast iron. Typically: (i) the first and second rings are secured to the housing via tongue and groove formations defined by the rings a nd housing; (ii) the first and second rings are adhered to the housing; a nd (iii) a locking member inhibits relative rotation of the first and second ¾ rings on the one hand and the housing on the other hand.

G enerally: (i) the first sealing element is secured to the first ring via tongue a nd groove formations defined by the first sealing element and the first ring; (ii) the second sealing element is secured to the second ring via tongue and groove formations defined by the 3Ί second sealing element and the second ring; and (iii) the first a nd second sealing elements are adhered to the first a nd second rings, res pectively.

P referably, the securing means is a clamping ring.

¾ Typically, the cylindrical race member, the housing and the first and second rings are a split cylindrica l race member, a split housing, and split first and second rings, respectively, for use with a split roller bearing.

G enerally, the first and second rings are secured to axial ends of the housing.

P referably: (i) the housing defines a radially inwa rds extending lip at each axial end of the housing; a nd (ii) a ring is secured to a radial inwa rds facing surface of each housing lip.

When assembled: the bearing mount further includes: a bea ring disposed between the t¾ race member and the housing; and a s haft to which the race member is secured by the securing mea ns.

BRIE F DE S C RIPTION OF T H E D RAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

F igu re 1 is an exploded perspective view of a bearing mount according to a t¾ preferred embodiment of the invention; F igu re 2 is an exploded perspective view of the bearing mount in F igure 1 including a bearing and a shaft;

F igu re 3 is a side diametric cross-sectional view of the bearing mount in F igure 1 including a bearing and a s haft in an assembled condition; and

F igu re 4 is a side diametric cross-sectional view of the bearing mount in F igure 1 including a bearing and a shaft in an assembled condition, following bea ring failure.

DE S C RIPTION OF T HE INVE NTION

With reference to F igures 1 to 4 of the drawings, a bearing mount 10 includes a race ¾ member 12, a housing 14, means 18 for securing the race member 12 to a rotating shaft 19 a nd rings 20.

In use, the bearing mount 10 together with a bea ring 22 (comprising a bea ring cage 24 and bea ring elements 26 in the form of rollers) is intended to be assembled over a shaft tfrl 19, so as to receive the shaft 19 axially there through, and rotatably secure the shaft 19 therein.

Although the bearing mount 10 has been shown as a bearing mount for a split bea ring, it will be appreciated that the bearing mount may a lso be used for a plummers block t¾ bearing, in which event, the bearing 22 will include spherical roller bearing elements 26 (or other configurations of bearing elements).

The race member 12 is cylindrical, and sized and sha ped to locate about the radia l surface of a shaft 19. The race member 12 defines: (i) a radially outwards facing surface t¾ along which, in use, bearing elements 26 revolve; and (ii) a radia l inwards facing surface that, in use, contacts the shaft 19. The minimum diameter of the radia l inwards facing surface of the race member 12 is intended to correspond to the diameter of the shaft 19. The race member 12 is divided diametrica lly into two pa rts. It will be appreciated that the race member 12 could be made of multiple pa rts, e.g. the radially outwards facing surface t¾ could be defined by a first part, the radia lly inwards facing surface could be defined by a second part, and these first and second pa rts could further be diametrically divided. This alternative arrangement is not shown. The securing means 18 is in the form of a clamping ring. In use, the clamping ring 18 secures the race member 12 against rotation to a shaft 19 by way of a friction fit. Typically, the securing means 18 extends radially beyond the radia l outwards facing ¾ surface of the race member 12. The clamping rings 18 are shown divided diametria lly into two parts.

The housing 14 is cylindrical, sized and sha ped to receive the race member 12 and securing means 18 radially therein while defining a n annular ga p between: the housing 14 3Ί on the one hand; and the race member 12 and securing mea ns 18 on the other hand.

The F igures show the housing 14 defining radially inwards extending lips 28 at its axial ends to define an annula r groove for, in use, receiving a bearing 22 (at least partially) therein. T he housing 14 is divided diametrica lly into two parts.

¾ Typically, the housing 14 is made of cast iron. P referably, the Moh s hardness of the housing is greater than 4.

The rings 20 (referred to as first and second rings) are circula r a nd made of a polymeric material, prefera bly Nylon, which material is able to withstand at least 130 degrees tfrl Celsius without deterioration. P referably, the Moh s hardness of the rings 20 is between 2 and 3.5. Importantly, the material of which the rings 20 are made has a Moh s hardness lower than the Moh s hardness of the materia l of which the housing 14 is made. The rings 20 are shown divided diametrially into two pa rts. It is s pecifically pointed out that the rings 20 a re not made of brass or any other metal.

The bearing mount 10 further includes a pair of sealing elements 30 (sometimes referred to in this specifiation as first and second sealing elements). E ach of the sealing elements 30 forms a closed loop. More specifically, each of the sealing elements 30 forms a closed circular ring. T he sealing elements 30 are made of a material that is more flexible and t¾ resilient tha n the rings 20, e.g. felt or extruded Neoprene. P referably, the Moh s hardness of the sea ling elements is less than 2. The outer diameter of the sealing elements 30 corresponds to the inner diameter of the rings 20, a nd the inner diameter of the sea ling elements 30 corresponds to the outer diameter of the shaft 19 that is, in use, received within the race member 12. The sealing elements 30 are shown divided diametria lly into t¾ two parts. The rings 20 are secured to the housing via corresponding tongue and groove formations defined by: the radial inwa rds facing surface of the housing 14 lips 28; and the radia lly outwards facing surface of the rings 20. Adhesive is a lso applied to secure such tongue and groove formations in place. F urther to inhibit relative rotation of the housing 14 and ¾ rings 20, locking members 32 in the form of a locking bolt extends through bores defined by the housing 14 lips 28 and into aligned threaded bores defined by the rings 20. The rings 20 extend radially inwa rds of the housing 14 lips 28. Although the Figures show the locking members 32 in the form of a locking bolt cooperating with a threaded bore defined by the rings 20, it will be appreciated that other mechanisms may be used to inhibit 3Ί relative rotation of the housing 14 a nd rings 20. For instance, a raised pip on the rings 20 could engage with a cavity or a perture defined by the housing 14 to inhibit relative rotation of the housing 14 a nd rings 20.

It will be appreciated that a lthough the rings 20 have been described as being secured to ¾ the radial inwa rds facing surface of the housing 14 lips 28, the rings 20 may alternatively be secured to the axial surfaces of the housing 14 (which need not define lips) (e.g. by bolts or screws); provided that, in each embodiment, the rings 20 extend radially inwa rds of the housing 14. tfrl S imilarly, the sealing elements 30 are secured to the rings 20 via corresponding tongue and groove formations defined by: the radial inwards facing surface of the rings 20; and the radially outwards facing surface of the sealing elements 30. Adhesive is a pplied to secure such tongue and groove formations in place a nd against relative rotation of the sea ling elements 30 and rings 20.

The F igures show the pairs of housing 14 lips 28, rings 20 and sealing elements 30 spaced axially from each other greater than the maximum axial dimension of the race member 12. In use, the rings 20 extend radia lly inwards from the housing 14 lips 28 beyond each axial end of the race member 12.

Turning to Figures 2 and 3, the bearing mount 10 is assembled as follows:

I T he race member 12 is located over the radial surface of a shaft 19. It should be pointed out that the shaft 19 does not form part of the unassembled bearing mount

10.

t¾ ί A bearing 22 is located over the radially outwards facing surface of the race member

12. It should be pointed out that the bearing 22 does not form part of the unassembled bearing mount 10. I S ecuring mea ns 18 are added to secure the race member 12 against rotation to the s haft 19.

I T he housing 14 with rings 20 secured thereto and with sealing elements 30 secured to the rings 20, are then located radia lly over the race member 12, securing means ¾ 18 and bearing 22. S o secured, the rings 20 extend radially inwards past the axial ends of the race member 12, and the sealing elements 30 contact / brush the shaft 19. It will be appreciated that the sealing elements 30, rings 20 a nd housing 14 lips 28 effectively close the annular gap between the housing 14 a nd the shaft 19, thereby inhibiting ingress of contaminants into the housing 14 and in the vicinity of 3Ί the bearing 22.

Importantily, the housing 14, race member 12, securing means 16 and rings 20 are sized and shaped such that:

¾> [A] < ([B]/2) where:

[A] (shown in Figure 3) is the minimal radia l spacing, in use, between: (i) the radial tfrl inwards facing surface of the housing 14 on the one hand; a nd (ii) the radial outwards facing surface of the securing mea ns 16 or race member 12 on the other hand; a nd

[B] is the difference between: (i) the minimum diameter D 1 (shown in F igure 3) of the radial inwards facing surface of the housing 14; and (ii) the minimum diameter D2 (shown t¾ in F igure 3) of the radial inwards facing surface of the race member 12. As previously mentioned, the minimum diameter of the radial inwards facing surface of the race member 12 is intended to correspond to the diameter of the shaft 19.

P referably, each of the first and second rings 20 together with their corresponding first t¾ and second sealing elements 30 extend radially inwards of the housing 14 (shown as dimension C in F igure 3) by at least [A]. More preferably, in use, effectively to seal the annular ga p between the housing 14 and the shaft 19, each of the first a nd second rings 20 with corresponding first a nd second sea ling elements 30 extend radially inwards from the housing 14 (shown as dimension B-B in Figure 3) a dista nce between 90% x ([B]/2) t¾ and 1 10% x ([B]/2). F igure 4 shows radial movement of the shaft 19 following bearing 22 failure. Upon bearing failure, the bearing elements 26 escape from the bearing cage 24, permitting the shaft 19, race member 12 and securing means 16 to move radially towards the housing 14. However, since [B]/2 > [A], the race member 12 or securing means 16 will contact the ¾ inner radial surface of the housing 14 before the s haft 19 contacts the housing 14. S uch contact between: the race member 12 or securing mea ns 18 on the one hand; and the housing 14 on the other hand, effectively (absent failure of the bearing mount 10 itself) prevents further radial movement of the shaft 19 towards the housing 14 lips 28. Accordingly, bea ring 22 failure results in the shaft 19 making contact with the rings 20Ί only. And, since the rings 20 are made of a softer material tha n the shaft 19, relative rotation of the shaft 19 and rings 20 results in wea r of the rings 20 in preference to the shaft 19. S ince the rings 20 are sacrificial, the shaft 19 will (absent failure of the bearing mount 10 itself) experience little to no wear consequent to bearing 22 failure. R

Claims

C LAIMS

A bearing mount including: a cylindrical race member defining: (i) an radially outwards facing surface along which, in use, bearing elements revolve; and (ii) a radial inwards facing surface that, in use, contacts a shaft extending axially through the race member; mea ns for, in use, securing the race member against rotation to a shaft extending axially through the race member; a cylindrical housing sized a nd sha ped, in use, to receive the race member and securing means radially therein while defining a n a nnular gap between: the housing on the one ha nd; and the race member a nd securing means on the other hand; first and second rings: (i) secured to the housing; (ii) extending radially inwards of the housing; and (iii) axially spaced from each other greater than the maximum axial dimension of the race member, in use, to extend radia lly inwards from the housing beyond each axial end of the race member; the housing being made of a first material a nd the first and second rings being made of a second material having a Moh s hardness less tha n the Moh s hardness of the first material; wherein:

[A] < ([B]/2) where:

[A] is the minimal radial s pacing, in use, between: (i) the radial inwards facing surface of the housing on the one ha nd; and (ii) the radially outwards facing surface of the securing mea ns or race member on the other hand; and [B] is the difference between: (i) the minimum diameter of the radial inwards facing surface of the housing; and (ii) the minimum diameter of the radial inwards facing surface of the race member.

¾

2. A bearing mount according to claim 1 , further including: a first sealing element extending radially inwards from, and continuously along the first ring to form a closed loop; a nd

3Ί a second sea ling element extending radially inwa rds from, and continuously along the second ring to form a closed loop.

3. A bearing mount according to claim 2, wherein each of the first and second rings together with their corresponding first and second sealing elements extend radially

¾ inwards of the housing by at least [A].

4. A bearing mount according to claim 3, wherein each of the first and second rings with corres ponding first and second sealing elements extend radially inwa rds from the housing a distance between 90% x ([B]/2) and 1 10% x ([B]/2).

tin

5. A bearing mount according to claim 4, wherein the first and second sealing elements are made of a material that is different to the material of which the first and second rings a re made. t¾

6. A bea ring mount according to claim 5, wherein the material of which the first and second sealing elements are made is more flexible a nd resilient tha n the material of which the first and second rings are made.

7. A bearing mount according to claim 6, wherein the first and second sealing t¾ elements a re made of felt or Neoprene.

8. A bearing mount according to claim 7, wherein each of the first and second rings is made of a polymeric material. t¾

9. A bearing mount according to claim 8, wherein each of the first and second rings is made of Nylon.

10. A bearing mount according to claim 9, wherein the housing is made of cast iron.

1 1 . A bearing mount according to claim 10, wherein:

¾ the first a nd second rings a re secured to the housing via tongue and groove formations defined by the rings and housing; the first and second rings a re adhered to the housing; and

3Ί a locking member inhibits relative rotation of the first and second rings on the one hand a nd the housing on the other hand.

12. A bearing mount according to claim 1 1 , wherein:

¾ the first sealing element is secured to the first ring via tongue and groove formations defined by the first sealing element and the first ring; the second sealing element is secured to the second ring via tongue and groove formations defined by the second sea ling element and the second tin, ring; and the first and second sealing elements a re adhered to the first a nd second rings, respectively. t¾ 13. A bearing mount according to claim 12, wherein the securing mea ns is a cla mping ring.

14. A bearing mount according to claim 13, wherein the cylindrical race member, the housing and the first and second rings are a split cylindrical race member, a split t¾ housing, and split first and second rings, respectively, for use with a split roller bea ring.

15. A bea ring mount according to claim 14, wherein the first a nd second rings a re secured to axial ends of the housing. A bearing mount according to claim 13, wherein: the housing defines a radia lly inwards extending lip at each axial end of the housing; and a ring is secured to a radial inwards facing surface of each housing lip.

A bearing mount according to claim 16, further including: a bearing disposed between the race member and the housing; a nd a shaft to which the race member is secured by the securing means.