WO1991005961A2

WO1991005961A2 - Thrust bearing assembly

Info

Publication number: WO1991005961A2
Application number: PCT/GB1990/001635
Authority: WO
Inventors: Richard Gozdawa
Original assignee: Advanced Bearing Technology Plc
Priority date: 1989-10-13
Filing date: 1990-10-15
Publication date: 1991-05-02
Also published as: WO1991005961A3; GB8923164D0

Abstract

The assembly (1), for a rotatable shaft intended to be used under axial thrust loading, comprises: (a) a bearing carrier ring (7) around a rotatable shaft (11); (b) housing members (2), each having an internal cavity (3) within which is mounted a bearing (4); (c) securing means (10) for releasably securing each housing member (2) to the bearing carrier ring (7).

Description

Thrust Bearing Assembly

The present invention relates to a thrust bearing assembly for a shaft intended to be used under axial thrust loading.

It is common practice to have a segmented ring of a silicon carbide or the like supporting an axial load in rotating machinery (typically a pump or the like) . These segments take many different forms, and are retained in many different ways.

It is important to prevent rotation of the segments, which would tend to occur if the segments were allowed to "float" freely, under the influence of the rotation of a thrust collar mounted on the shaft.

U.S. Patents 4738550 and 4456391 disclose tilting pad thrust bearings having segments mounted on tilting and rotation-inhibiting mechanisms located within an annular housing. Traditionally, the annular housing is of a "heavy" construction, which is disadvantageous where a bearing having only a small number of thrust segments is required. Additionally such thrust bearings are conventionally designed for "one off" applications, from non-standard components, which adds to the expense of manufacture in terms of tooling up and design costs. According to the present invention there is provided a thrust bearing assembly for a rotatable shaft, which assembly comprises:

(a) a bearing carrier ring, locatable around a rotatable shaft;

(b) a plurality of housing members, each having side walls defining a cavity, each cavity having mounted therein and movable relative thereto a respective bearing element, each said bearing element having a bearing surface provided thereon such that said bearing surface projects from said housing and makes bearing contact either with said shaft or with a component attached to said shaft; and

(c) securing means provided for individually releasably securing each housing member to said bearing^* carrier ring.

It is preferred that each bearing element and respective housing is provided with biasing means for urging the bearing element into bearing contact with the rotatable shaft or component attached thereto. The biasing means preferably comprises at least one disc spring disposed in the housing cavity, preferably between the carrier ring and the respective bearing element.

It is further preferred that each cavity and respective bearing element are shaped and dimensioned so as to substantially inhibit rotation of the bearing element within the housing about an axis substantially normal to the bearing surface.

It is preferred that each bearing surface is substantially planar. Preferably each bearing surface makes bearing contact with the surface of an annular component secured to the rotatable shaft, which surface is advantageously plana .

Preferably the plane of bearing contact is substantially perpendicular to the axis of rotation of the shaft. It is preferred that the individual securing means comprises one or more threaded bolts provided for each housing member passing through and engaging with corresponding threaded holes provided in the housing member and the bearing carrier ring.

It is further preferred that a plurality of threaded holes are provided on the bearing carrier ring at suitable dispositions enabling a variety of different numbers and configurations of bearing elements and housing members to be accomodated.

Preferably, two bearing assemblies are used together in an opposed configuration, to accomodate axial thrust in longitudinally opposed directions of the shaft.

I

In use, bearing lubrication means is provided utilising a suitable lubricant such as water, oil or the like, which lubrication is preferably hydrodynamic.

The invention will be further described, by way of example only, in a particular embodiment, with reference to the accompanying drawings in which:

Figure 1 is a sectional view of a bearing housing and bearing element according to the invention;

Figure 2 is a schematic representation of the housing and bearing element of Figure 1.

Figure 3 is a plan view of a bearing assembly according to the invention.

Figure 4 is a scrap section, along Z-Z, through the bearing assembly of Figure 3 when the assembly is fitted to a shaft.

Referring to Figures 1 to 4, a bearing sub-assembly, generally designated 1, comprises a housing 2, having an internal cav; -y 3 within which is mounted a bearing 4. The bearing 4 has a planar bearing surface 5, which projects above the level of the housing 2, and in use makes a bearing contact surface with a thrust collar 6. A clearance gap exists between the sides of the bearing 4 and the walls of the cavity 3, which facilitates a lateral tilting movement of the bearing 4 within the housing. Rotation of the bearing 4 within the housing 2 is inhibited by the complementary shape of the cavity 3 and adjacent side walls 4a of the bearing 4. The bearing 4 is also movable relative to the housing so as to allow the distance of projection of the bearing surface 5 above the housing 2 to be varied.

The lateral tilting movement of the bearing 4, and variation of projection of the bearing surface 5, provide a self aligning-mechanism for the bearing 4 with the thrust collar 6, controlled by biasing disc springs 8 which are positioned in the cavity 3 in abutment with the base of the bearing 4 and an adjacent fixing plate 9. In operation, such a self-aligning capacity is needed in cases where, for example, the thrust collar 6 or carrier ring 7 are not positioned perfectly squarely relative to the shaft. The disc springs 8 not only serve to bias the bearing surface 5 into bearing contact with the thrust collar 6, but also to transmit the axial thrust forces from the shaft 11 through the housing 2 to the carrier ring 7. Two threaded fixing bolts 10 are located through the housing 2 on opposed sides of the bearing 4, for mating engagement with complementary bored and threaded holes provided in the carrier ring 7.

Referring specifically to Figures 3 and 4, the bearing assembly comprises three bearing sub-assemblies bolted around a cirumfrential bearing axis 12 to a carrier ring 7. The thrust collar comprises two components 6a and 6b, with the retaining collar 6a having an interference fit with the shaft 11, and the inner collar 6b, the retaining collar 6a, and the inner collar 6b therefore both rotate as one with the shaft 11. The inner collar 6b has an annular planar surface 13 which makes bearing contact with the bearing surface 5 of each bearing 4. The carrier ring 7 is fixed to an external structure 14, to which the axial thrust forces acting on the shaft are transferred as described above. The bearing assembly has been described in an embodiment having three bearing sub-assemblies, but a bearing configuration could be utilised using various numbers and arrangements of sub-assemblies mounted in a carrier ring provided with a suitable arrangement of threaded holes for receiving the fixing bolts. This enables a bearing designer to "build up" a bearing suited to particular requirements from "off the shelf" standard bearing components. The exact number of sub-assemblies is determined by the axial thrust being divided by the load-carrying capacity of each sub-assembly.

Claims

Clai s :

1. A thrust bearing assembly for a rotatable shaft, which assembly comprises:

(a) a bearing carrier ring, locatable around a rotatable shaft;

(b) a plurality of housing members, each having side walls defining a cavity, each cavity having mounted therein and movable relative thereto a respective bearing element, each said bearing element having a bearing surface provided thereon such that said bearing surface projects from said housing and makes bearing contact either with said shaft or with a component attached to said shaft; and '

(c) securing means provided for individually releasably securing each housing member to said bearing carrier ring.

2. A thrust bearing assembly according to claim 1, wherein each bearing element and respective housing is provided with biasing means for urging the bearing element into bearing contact with the rotatable shaft or component attached thereto.

3. A thrust bearing assembly according to claim 2, wherein the biasing means comprises at least one disc spring disposed in the housing cavity.

4. A thrust bearing assembly according to any preceding claim, wherein each cavity ana respective bearing element are shaped and dimensioned so as to substantially inhibit rotation of the bearing element within the housing about an axis substantially normal to the bearing surface. -7-

5. A thrust bearing assembly according to any preceding claim, which further comprises an annular component to be secured to the rotatable shaft, each bearing surface being arranged to make bearing contact with asurface of said annular component.

6. A thrust bearing assembly according to any preceding claim, wherein the plane of bearing contact is substantially perpendicular to the axis of rotation of the shaft.

7. A thrust bearing assembly according to any preceding claim, wherein the individual securing means comprises one or more threaded bolts provided for each housing member passing through and engaging with corresponding threaded holes provided in the housing member ano the bearing carrier ring.

8. A thrust bearing assembly according to claim 7, wherein a plurality of threaded holes are provided on the bearing carrier ring at suitable dispositions enabling a variety of different numbers and configurations of bearing elements and housing members to be accomodated.

9. A thrust bearing assembly according to any preceding claim, wherein the bearing is hydroαyna ically lubricated.

10. Machinery incorporating a thrust bearing assembly according to any preceding claim.