SE1551146A1

SE1551146A1 - Axial load sharing

Info

Publication number: SE1551146A1
Application number: SE1551146A
Authority: SE
Inventors: Jonas Kullin
Original assignee: Skf Ab
Priority date: 2015-09-08
Filing date: 2015-09-08
Publication date: 2016-02-26

Abstract

An assembly for distributing an axial load (116) between a plurality of thrust bearings (104) is disclosed. The assembly. (107) has a load divider (122) configured to extend transversely to the shaft (100), a first connector (124) configured to be coupled the housing washer (110) of a first thrust bearing (104), and a second connector (126) configured to be coupled to the housing washers (110) of the remaining thrust bearings (104) . The load divider (122) is configured to distribute a load (116) between the first connector (124) and the second connector (126) and to adjust to a change in the relative position of the first connector (124) and the second connector (126) along the shaft (100).Publication picture: Figure 2

Description

1 201500376 AXIAL LOAD SHARING Technical field of the Invention The present invention relates generally to the field ofdevices for supporting shafts or journals. The presentinvention relates specifically to the field of load balancing and load sharing.

Background of the Invention In many situations, the axial load on a shaft can behigh, but the available radial space limited. For example,this is typically the situation for the shaft driving thescrew in an extruder. With these restrictions, it is hard tofind a single bearing that can fit in the available space andcarry the load.

The traditional solution for this is to place or stack aplurality of thrust bearings in a sequence on a shaft. Aconnector is provided that distributes the axial load betweenthe plurality of thrust bearings. Each thrust bearing has ashaft washer that is centered on the shaft, a housing washer,and rolling elements between the shaft washer and the housingwasher that enables a rotation them between. The connector isthen coupled to the housing washer of each thrust bearing sothat the load is shared between the thrust bearings.

To ensure the load sharing in the traditional solutions,the tolerances of both the shaft and the thrust bearings mustbe tight.

Further, due to deflection and deformations of the components involved, the desired distribution of the loadbetween the thrust bearings is typically achieved only at narrow interval of load levels.

Summary of the Invention Thus, it is an object to obviate the aforementioned disadvantages of the known techniques, and to provide animproved distribution of the load between the thrustbearings. It is also an object to provide an improved assembly for distributing an axial load between a plurality 2 201500376 of thrust bearings stacked in a sequence. Additionally, it isan object to allow for a replacement of a few large thrustbearing with several smaller thrust bearings. Further objectsmay also be construed from the summary and description below.

According to a first aspect, the above objects areachieved by an assembly for distributing an axial loadbetween a plurality of thrust bearings. The plurality ofthrust bearings are placed in a sequence on a shaft, and eachthrust bearing comprises a shaft washer for being centered onthe shaft, a housing washer, and rolling elements between theshaft washer and the housing washer for allowing a rotationthem between.

The assembly is configured to be coupled to the housinga load divider washer of each thrust bearing, and comprises: configured to extend transversely to the shaft. The assemblyfurther comprises: a first connector configured to extendalong the shaft and to be coupled the housing washer of thefirst thrust bearing in the sequence of thrust bearings.Additionally, the assembly comprises: a second connectorconfigured to extend along the shaft and to be coupled to thehousing washers of the remaining bearings in the sequence ofthrust bearings.

The load divider is configured to distribute a loadbetween the first connector and the second connector and toadjust to a change in the relative position of the firstconnector and the second connector along the shaft formaintaining the distribution of the load between the firstconnector and the second connector.

A change in the relative position is here understood toencompass a deformation affecting the relative position. Forexample an elongation or shortening of a connector along theshaft effects the position of the end points of theconnector, thus also affecting the relative position to the other connector. Here, a load may encompass the expected loadunder expected operation conditions.

The load divider has the effect that lower precisioncomponents can be used for the shaft, the thrust bearings, and the assembly as such with the intended load distribution 3 201500376 maintained. Further, less rigid components can also be used,since the assembly adjusts to deflections and deformations.

The plurality of thrust bearings may be configured to befixed longitudinally with respect to the shaft. Additionallyor alternatively, the plurality of thrust bearings maycomprise three or more thrust bearings.

The first connector may be configured to engage the loaddivider at a first radius with respect to the shaft, and thesecond connector may be configured to engage the load dividerat a second radius with respect to the shaft. The assemblymay further comprise: a third connector configured to engagethe load divider at a third radius with respect to the shaft.The third connector may be configured to transfer a load tothe load divider. Further, the first radius may be smallerthan the third radius and the second radius may be greaterthan the third radius. This has the effect that a load fromthe third connector is distributed to the first and secondconnectors and that a moment generated by the first connectorto some extent can be counteracted by a moment generated bythe second connector, thus reducing deflections and deformations in the assembly. For example, if both the firstradius and the second radius were greater than the thirdradius, no counteracting moments would be generated and thecomponents of the assembly could deform.

The load divider may be configured to balance a load atthe first radius and a load at the second radius with respectto the third radius. Again, a load is here understood toencompass the expected load under expected operationconditions. The balancing means that the expected load fromthe first connector results in a moment of the same magnitudebut counteracting the moment resulting from the expected loadfrom the second connector. This has the effect that internalmoments in the assembly are reduced, thus contributing toreduce deformations and deflections.

The first thrust bearing in the sequence of thrustbearings may be configured to carry a first load and theremaining thrust bearings in the sequence of thrust bearings may be configured to jointly carry a second load. Further, 4 201500376 the ratio between the difference between the first radius andthe third radius and the difference between the second radiusand the third radius may be approximately equal to the ratiobetween the second load and the first load. Here, the firstload and the second load may be the expected operation loads.This has the effect that the loads from the first and secondconnectors are balanced with respect to the third connector.The load divider may be configured to pivot with respect to the third radius. Alternatively or additionally, the loaddivider may be resiliently deformable for conforming to theposition of the first connector and the position of thesecond connector under operation of the assembly. This hasthe effect that the contact can be maintained between theload divider and the connectors, even though the connectors shift relative to one another. Here, operation of isunderstood to encompass the intended operation of theassembly. These features have a function that is analogous tothe function of a bogie, but in a circular symmetric geometryinstead of a linear geometry.

The load divider may comprise a first side and anopposite second side. The first connector may be configuredto engage the load divider on its first side, the secondconnector may be configured to engage the load divider on itsfirst side, and the third connector may be configured toengage the load divider on its second side. This allows for acompact assembly with a reduced radial extension.

The load divider may be flat, have an annular shape andbe configured to be concentric with respect to the shaft. Theload divider may have an outer edge with a radius that isgreater than the second radius, and an inner edge with aradius that is smaller than the first radius.

Additionally or alternatively, the load divider may beconfigured to twist with respect to the third radius forconforming to the first connector and the second connector.This may be at installment and/or under operation of theassembly.

Alternatively or additionally, the first connector may be configured to engage the load divider at three or more first 5 201500376 engagement points and the second connector may be configuredto engage the load divider at three or more second engagementpoints. The load divider may comprise three or more leversand a first engagement point and a second engagement point islocated on each lever. The levers are further configured foradjusting to a change in the relative position of the firstconnector and the second connector along the shaft. The firstengagement points and the second engagement points may belocated at the same radius with respect to the shaft. Eachlever may comprise a beam oriented in a tangential directionwith respect to the shaft. Each lever may further comprise afulcrum or hinge and the first and second engagement pointsare located on different sides of the lever with respect tothe fulcrum or hinge.

The first connector may have a tubular shape and thesecond connector may have a tubular shape. The thirdconnector may have a circular end portion configured toengage the load divider. These features allows for a simpleand robust construction of the assembly.

According to a second aspect, the above objects areachieved by a shaft support for supporting a shaft. The shaftsupport comprises: a plurality of thrust bearings configuredto be placed in a sequence on the shaft. Each thrust bearingcomprises a shaft washer for being centered to the shaft, ahousing washer, and rolling elements between the shaft washerand the housing washer for allowing a rotation them between.The shaft support further comprises: an assembly fordistributing an axial load between the plurality of thrustbearings. The assembly is configured to be coupled to thea load The housing washer of each thrust bearing and comprises:divider configured to extend transversely to the shaft.assembly further comprises: a first connector coupled the housing washer of the first thrust bearing in the sequence ofthrust bearings and configured to extend along the shaft.

Additionally, the assembly comprises: a second connectorcoupled to the housing washers of the remaining bearings inthe sequence of thrust bearings and is configured to extend along the shaft. 6 201500376 The load divider is configured to distribute a loadbetween the first connector and the second connector and toadjust to a change in the relative position of the firstconnector and the second connector along the shaft formaintaining the distribution of the load between the firstconnector and the second connector.

The assembly of the shaft support according to the secondaspect may comprise any of the features described in relationto the assembly of the first aspect.

Further advantages with and features of the inventionwill be apparent from the appended claims as well as from the following detailed description of preferred embodiments.

Brief description of the drawings A more complete understanding of the abovementioned andother features and advantages of the present invention willbe apparent from the following detailed description in conjunction with the appended drawings, wherein: Fig. 1 is a schematic cross sectional side view of shaftfitted with a known shaft support, andFig. 2 is a schematic cross sectional side view of shaft fitted with a shaft support according to an embodiment of the present invention.

Detailed description of preferred embodiments of the inven- tion 1 is a schematic cross sectional side view of shaft 100The depicted Fig.fitted with a known shaft support 102.components and features are circular symmetric with respectto the shaft 100. The shaft support 102 has three thrustbearings 104 and a connector 106.

Each thrust bearing 104 has a shaft washer 108 flushwith and centered on the shaft 100, a housing washer 110, androlling elements 112 between the shaft washer 108 and thehousing washer 110 so that they can rotate with respect to one another. 7 201500376 The connector 106 is coupled to the housing washer 110of each thrust bearing 104 and distributes an axial load 116(illustrated as an arrow) between the thrust bearings 104.The shaft has an abutment 114 preventing the shaft washers108 from moving along the shaft 100 when subjected to theload 116 from the connector 106. Spacers 118 are positionedand between the outermost The axial load 116 is between the shaft washers 108,shaft washer 108 and the abutment 114.transferred via the thrust bearings 104 and the spacers 118to the shaft 100 via the abutment 114. The shaft is held inequilibrium by a counteracting load 120 (illustrated as anarrow).

The thrust bearing 104 are of the same type. Tighttolerances of all components of the shaft support 102 arerequired for the three thrust bearings to carry the sameload. A small axial play in one of the thrust bearings 104means that less or no load is carried by this thrust bearing104, bearings 104. and the load is increased on the remaining thrustAn axial play may also be caused bydeformations and deflections, for example in the radialportions of the connector 106, or by wear of the thrustbearings 104.

Fig. 2 is a schematic cross sectional side view of ashaft 100 fitted with a shaft support 102 according to anembodiment of the present invention. Features having the sameform or function as in Fig. 1 have been given the same numberindexing. Only difference with respect to the shaft support102 described in relation to Fig. 1 are described here.Tnstead of a connector 106, the shaft support 102 has anassembly 107 that is coupled to the housing washer 110 ofeach thrust bearing 104. The assembly 107 has a flat loaddivider 122 with an annular shape and that is concentric withrespect to the shaft 100,shaft 100.

The assembly 107 further has a tubular first connector The first thus extending transversely to the 124 centered on and extending along the shaft 100.connector 124 is coupled or connected to the housing washer 110 of the first thrust bearing 104 in the sequence of thrust 8 201500376 bearings 104 on the shaft 100. Additionally, the assembly 107has a second connector 126 composed of a number of tubularsections 128 and a flat annular shaped portion 130. Thesecond connector 126 extend along the shaft 100 and iscoupled to the housing washers 110 of the remaining bearingsin the sequence of thrust bearings 104.

The first connector 124 engages the load divider 122 at afirst radius with respect to the shaft 100, and the secondconnector 126 engage the load divider 122 at a second radiuswith respect to the shaft 100. The assembly 107 also has athird connector 136 with a circular end portion 142 thatengages the load divider at a third radius with respect tothe shaft 100.

The first radius is smaller than the third radius, andthe second radius is greater than the third radius. Further,the load divider 122 has outer edge 132 and an inner edge 134, the second radius, and the outer edge 132 has a radius that is greater thanand the inner edge 134 has a radius thatThe load divider has a 140. The firstengage the load is smaller than the first radius.first side 138 and an opposite second sideconnector 124 and the second connector 126divider 122 on its first side 138, and the third connector136 engages the load divider 122 on its second side 140.

All thrust bearings 104 are manufactured to carry thesame load. Thus, the first thrust bearing 104 in the sequenceof thrust bearings carries a first load and the remaining twothrust bearings in the sequence jointly carry a second loadthat is twice the first load. The difference between thefirst radius and the third radius is twice the differencebetween the second radius and the third radius. Thus, theratio between the difference between the first radius and thethird radius and the difference between the second radius andthe third radius is equal to the ratio between the secondload and the first load.

The load divider 122 is configured to pivot with respectto the third radius. Furthermore, its planar shape allows itto flex and twist with respect to the third radius so that it can conform to the position of the first connector 124 and 9 201500376 the position of the second connector 126 if small shifts inthe relative position occur under operation of the assembly.the annular load divider 122 has a thus In one embodiment,wavelike shape when viewed along the shaft 100,enhancing its ability to resiliently deform.With the above described configurations and features, theload divider 122 is configured to balance a load at the firstradius and a load at the second radius with respect to thethird radius. Further, the load divider 122 is configured todistribute a load between the first connector 124 and thesecond connector 126 and to adjust to a change in therelative position of the first connector 124 and the secondconnector 126 along the shaft 100 for maintaining thedistribution of the load between the first connector 124 andthe second connector 126.

The tubular sections 128 and the annular shaped portion 130 are arranged so that the annular shaped portion 130 hasthe same principal function as the load divider 122 describedabove.

Feasible modifications of the Invention The invention is not limited only to the embodimentdescribed above and shown in the drawings, which primarilyhave an illustrative and exemplifying purpose. This patentapplication is intended to cover all adjustments and variantsof the preferred embodiments described herein.

It should be pointed out that all the elements orcomponents described above may be manufactured of metal, butother materials that are suitable for the intended purposemay also be used, such as ceramics. A thrust bearing is hereunderstood to encompass a bearing that that is configured to support a predominately axial load.

Item list 100102 shaftshaft support104 thrust bearing 106 connector 107108110112114116118120122124126128130132134136138140142 assembly shaft washerhousing washerrolling elementsabutment load spacercounteracting loadload divider first connectorsecond connectortubular sectionsannular shaped portionouter edge inner edge third connectorfirst side second side circular end portion 201500376

Claims

11 201500376

1. Claims1. An assembly (107) for distributing an axial load (116)between a plurality of thrust bearings (104), wherein the (104)and each thrust bearing (104) plurality of thrust bearings(100),(108)housing washer (110),(108) a rotation them between, are placed in a sequenceon a shaft comprising a(100), a between the shaft washer for being centered to the shaft (112)(110) for allowingand wherein the assembly (107) is (110) and rolling elementsshaft washer and the housing washerconfigured to be coupled to the housing washer of eachthrust bearing (104), (107) configured to extend transversely to characterized by the assembly(122) comprising:- a load dividerthe shaft (100);- a first connectorshaft (100)first thrust bearing (104)(l04); - a second connector configured to extend along theshaft (100) (110) ofthe remaining bearings in the sequence of thrust bearings(l04);the load divider(116) connector (124) and to be coupled the housing washer configured to extend along the(110) of the in the sequence of thrust bearings (126) and to be coupled to the housing washers wherein (122)between the first connector(126)position of the first connectorconnector (126) along the shaftdistribution of the load (116)(124) is configured to distribute a load(124)and to adjust to a change in the relative(124)(100)between the first connector(126) and the second and the second for maintaining the and the second connector

2. The assembly (107)(124)at a first radius with respect to the shaft(126)at a second radius with respect to the(107) according to claim 1, wherein thefirst connector (122)the second connector(122) and the assembly is configured to engage the loaddivider(100), load dividershaft (100), is configured to engage the further comprises: 12 201500376 (136)at a third radius with respect to the shaft - a third connector(122) wherein configured to engage the loaddivider(100);the first radius is smaller than the third radius and thesecond radius is greater than the third radius. (107) wherein the is configured to balance a load at the

3. The assembly(122) first radius and a load at the second radius with respect to according to claim 2, load dividerthe third radius.

4. The assembly (107) whereinthe first thrust bearing (104)(104)remaining thrust bearings (104) and wherein the ratio between the difference between the according to claim 2 or 3,in the sequence of thrust is configured to carry a first load and the(104) are configured to jointly carry a second load, bearingsin the sequence of thrust bearings first radius and the third radius and the difference betweenthe second radius and the third radius is approximately equal to the ratio between the second load and the first load. (107) wherein the load divider according to any of the claims 1-4, (122)conforming to the position of the first connector(126)

5. The assemblyis resiliently deformable for(124) under operation of andthe position of the second connectorthe assembly (107).(107) wherein the load divider according to any of the claims 1-5,(122) (138)(140), (124)is configured to engage the load divider on its first(138), the second connector (126)engage the load divider (122) on its first side(136) on its second side

6. The assemblycomprises a first side the first connector(122)is configured to(138), is configured to engage the load(140). and an opposite second side sideandthe third connectordivider (122)(107) wherein the load divider according to any of the claims 1-6(122) is flat,

7. The assembly has an annular shape 13 201500376 and is configured to be concentric with respect to the shaft(100). (107) wherein theis configured to twist with respect to the(124)

8. The assembly according to claim 7,(122) third radius for conforming to the first connector load divider and the second connector (126) under operation of the assembly(107).

9. The assembly (107) according to any of the claims 2-8,wherein the first connector (124) has a tubular shape and the second connector (126) has a tubular shape. (102) wherein the shaft support for supporting a shaft (100),(102) - a plurality of thrust bearings

10. A shaft supportcomprises:(104)(100),comprising a shaft washer(100), between the shaft washer configured to bewherein each thrust(108) a housing washer placed in a sequence on the shaftfor being(110),(108) for allowing a rotation them between, bearing (104)centered to the shaftrolling elements (112)(110)(107)between the plurality of thrust bearingsassembly (107)(110) assembly and and thehousing washerfor distributing an axial load (116)(104), is configured to be coupled to the housing - an assembly wherein the of each thrust bearing (104),(107)(122) washer characterized by the comprising:- a load dividershaft (100);- a first connector (124)the first thrust bearing (104) (104) configured to extend transversely to (110) of in the sequence of thrust coupled the housing washerbearings and configured to extend along the shaft(l00); - a second connector(110)bearings(l00);the load divider(116) (126)of the remaining bearings in the sequence of thrust(104) wherein coupled to the housing washers and configured to extend along the shaft (122) between the first connector is configured to distribute a load (124) and the second 14 201500376 connector (126) and to adjust to a change in the relativeposition of the first connector (124) and the secondconnector (126) along the shaft (100) for maintaining thedistribution of the load (116) between the first connector 5 (124) and the second connector (126).