Bearing Compression Strap

A tensioning arrangement for a bearing ring is disclosed, which introduces compressive force towards a rotational centre of the bearing ring, to prevent bearing ring distorting as a shaft supported by the bearing turns. The tensioner arrangement comprises a strap and a tensioner. The strap has a connector at each end, and tensioner has a means for connecting to the connectors. The tensioner also has a means for applying tension to the strap. In use, the strap is arranged around the bearing ring and a circumferential length of the strap in contact with the bearing ring is reduced, thereby applying compressive force to the bearing ring.

BACKGROUND OF THE INVENTION

The present invention relates to a bearing ring, and more particularly to a tensioning arrangement for a bearing ring. The arrangement provides a circumferentially distributed force towards the rotational centre of the bearing ring.

FIG. 1shows a schematic of a typical bearing arrangement10having an outer bearing ring12, a bearing race14, and an inner bearing ring16. Inner bearing ring is typically journaled to a shaft (not shown).

A problem with large bearings, is that the bearing ring12can distort as the shaft is loaded.

BRIEF SUMMARY OF THE INVENTION

The present invention solves this problem by applying a circumferentially distributed force18towards a rotational centre of the bearing ring.

According to one aspect, the present invention provides a tensioning arrangement for a bearing ring comprising a strap and a tensioner. The strap comprises a connector at each end, and tensioner comprises means for connecting to the connectors. The tensioner also comprises means for applying tension to the strap. In use, the strap is arranged around the bearing ring and a circumferential length of the strap in contact with the bearing ring is reduced, thereby applying compressive force to the bearing ring.

DETAILED DESCRIPTION OF THE INVENTION

Referring now toFIG. 1B, which shows a conceptual schematic of a tensioning arrangement100, first end A and second end B of a strap108are connected to a tensioner105. The tensioner comprises means15for applying tension to the strap. One end B of the strap is connected to the tensioning means, and the tensioning means pulls end B into the tensioner105which shortens the strap. When the tensioning arrangement is arranged around a bearing ring (not shown), continued actuation of the tensioner tightens and stretches the strap and increases the tension in the strap108and hence introduces compressive force towards a rotational centre of the bearing ring. The tension introduced into the strap is dependent on the size of the bearing and its application: values are typically greater than 25 kN for smaller bearings, typically greater than 50 kN for medium size bearings and over 75 kN for large bearings.

Referring now toFIG. 2, which shows a tensioning arrangement for a bearing ring, a strap108is connected to a tensioner105. The strap has a connector at or near each end, and in the example shown, the strap is a wire rope and the connectors comprise swaged studs or buttons106a,110aon the ends (A and B, respectively) of ropes108. The stud110aon one end (B) of the wire rope comprises a thread. The other stud106ais plain with a larger diameter than the rope. These connect to the tensioner105. Tensioner105comprises a mount plate104. The tensioning arrangement is shown fitted to a bearing ring102.

Referring now toFIGS. 2 to 8, which show further views of the tensioning arrangement ofFIG. 1, the end (A) of the strap component108comprising the plain stud106ais anchored in slot106bin mount plate104. As can be seen inFIG. 4, the other end (B) of strap108passes through the outer part of the connector110a. Tensioner105comprises a mount plate104which comprises a channel or hole110b(shown as a dotted line) and the end (B) of the strap108comprising the threaded stud110apasses through the channel110band is secured against the mount plate104by engaging with nut112. The tensioner105, comprising the threaded stud110a, the mount plate104and the nut112, operates to pull strap108through mount plate104as the nut is tightened. A separate tool typically tightens the nut thereby increasing the tension in the strap. As the strap is anchored at the other end (A) by connector106ain slot106b, this means that the length of the strap108arranged around the bearing ring102is reduced. Thus the tension in the rope108is increased and hence a compressive force towards the rotational centre of the bearing ring is increased. The compressive force is sufficient to prevent the bearing ring from distorting as the shaft is loaded The mount plate104is designed to enable the use of bolt tensioning equipment to ease the tightening process. Mount plate104can be in contact with bearing ring102in use.

Strap100is fitted to bearing ring102, or a component housing a bearing ring. Bearing ring102, or a component housing a bearing ring, is an existing component and is not part of the present invention. A tensioning force is applied to the strap which prevents the space provided by the bearing ring from being distorted in use.

In the example of the invention shown inFIGS. 2 to 8, the strap component108comprises one or more elements, such as the ropes shown, and these surround the circumference of the bearing ring102in use. Furthermore, the connector106ais shown as connecting to mount plate104via slot106b. The skilled person will appreciate that the same overall effect would be achieved by directly and permanently connecting the mount plate to the one end of the strap108.

Referring now toFIGS. 9 and 10, which show a further example of tensioner arrangement in isometric and side view, respectively, a strap component108is connected to a tensioner105. The strap component has a connector at each end, and in the example shown, the strap component comprises a swaged stud110aon one end (B) of ropes108as described above. In this example, the connector at the other end (A) of strap component108is provided by loop122formed in the strap component in which the end of the strap component is looped and anchored to the strap component by an anchor120. The loop122is mounted around mount plate104and is held in place by channels (see below). Mount plate104can be, in use, in contact with bearing ring102. Also shown on this view is the envelope130a tensioning device would occupy during attachment of the strap assembly to the bearing. The strap is tensioned by tightening nut112as described above.

Referring now toFIGS. 11A-D, which shows further views of mount plate104, channels132,134and136are formed in tensioner105which serve to retain the strap component in place and also prevent damage to the strap by sharp edges in the tensioner when the strap component is tensioned. Channel110bpasses through tensioner105, as shown in particular inFIG. 11D.

The strap100can be fitted before or after the bearing is attached to other machine components.

In the embodiment described, the tensioning arrangement is held in place against the bearing ring when tensioned; mounting means are not essential.

In a further embodiment the tensioning arrangement includes retainers to locate the rope on the circumference of the bearing ring. These serve to hold the mount plate if the strap components were to break, and further prevent the cables from falling away from the bearing ring.

Although strap component108as shown in the examples comprises a rope, other suitable strap components108can, for example, comprise a chain or a band.

Similarly, the means for applying tension can be, for example, comprised of ratchets or gearing.

Ratchet tensioners are well known, and a typical ratchet tensioner1200is shown inFIG. 12. It comprises a spool1210, a ratchet and associated gears1230and a handle1220, and is a mechanical device which is typically used to tighten straps108.

Other strap/tensioner arrangements include hose clamps, T-bolt clamps, and straps having preformed holes and a buckle.

In a further example, a wind turbine bearing comprising the tensioning arrangement is disclosed. In particular the tensioner arrangement is engaged around the outer circumference of a blade pitch bearing located between the blades and the rotor hub, and held in place by a steel bracket104. This introduces a compressive force onto the bearing which reduces tensile stresses within the bearing rings and improves pitch bearing life.