GB2073334A - Lubrication apparatus and method - Google Patents

Abstract

Bearings 5 on a high speed shaft 10 are automatically lubricated by lubrication fluid F from a reservoir 15 beneath the shaft. Automatic lubrication is achieved by gravitionally suspending a large diameter ring 20 from the shaft so that the ring carries fluid to the nip between the inner surface of the ring and the shaft, and by providing fluid accelerating discs 25 adjacent the nip for centrifugally accelerating a portion of the fluid and for tangentially discharging it into a secondary reservoir 31 by which it may be transferred by gravitational feeds 34 to the bearings 5. <IMAGE>

Description

SPECIFICATION Lubrication apparatus and method The invention relates to the method and apparatus for effecting the automatic lubrication of bearings supporting a high speed rotating shaft from a source of lubricating fluid contained in a reservoir.

Lubricating systems employing lubrication reservoirs are well known in the prior art. In the past, two means have commonly been employed to effect the transfer of the lubricating fluid from the reservoir to the bearings mounting the shaft. One such means takes the form of an enlarged ring which rests on the shaft and is rotated at a substantially reduced speed solely by frictional engagement with the shaft. The lower portion of the ring extends into the lubricating reservoir and the lubricant adhering to the ring is transferred to the shaft surface as the ring rotates. This system is effective for relatively low speed shafts wherein the viscosity of the lubricating fluid will cause it to adhere to the shaft and move axially along the shaft by surface attraction to enter the shaft bearings.However, in the case of high speed shafts, for example operating at speeds on the order of 7,000 to 10,000 rpm, the centrifugal force is so great that the lubricant is thrown off the shaft before it ever reaches the bearings.

A second lubricating system employed with lubricant reservoirs involves the utilization of one or more discs which are secured for corotation to the shaft and wherein the periphery of the disc enter the lubricating fluid contained in the reservoir. Again, this type of system is practically inoperative when high rotational speeds of the shaft are involved, due to the discharge of the lubricating fluid from the periphery of the disc by centrifugal force. Moreover, this system requires that the level of the lubricating fluid in the reservoir be maintained substantially constant because the amount of fluid picked up by the rotating disc and the energy loss due to frictional drag on the high speed rotating disc, is a direct function of the depth of insertion of the rotating disc in the lubricating fluid.

Neither of the previously utilized systems for effecting the transfer of lubricating fluid from a reservoir to the bearings of a shaft are desirable when the automatic lubrication of high speed shaft bearings from a reservoir is required.

Apparatus according to the invention for lubricating a shaft bearing with fluid from a reservoir beneath the shaft comprises the reservoir, a ring that has a diameter greater than the shaft and that can be gravitationally suspended from the shaft with the lower portion of the ring passing through the reservoir so that, upon rotation of the shaft, the inner surface of the ring can carry fluid from the reservoir up to the nip between the inner surface and the shaft, and means for centrifugally accelerating at least a portion of the fluid carried to the nip and thereby tangentially discharging that fluid.

In use the apparatus therefore comprises the shaft having at least one bearing, the reservoir positioned beneath the shaft, the ring gravitationally suspended from the shaft with the lower portion of the ring passing through the reservoir, and the centrifugally accelerating means mounted on the shaft for co-rotation with the shaft.

The means for centrifugally accelerating fluid are generally a fluid accelerator comprising at least one substantially radial surface and that can be mounted on the shaft for corotation with the shaft with the or each substantially radial surface in a position to receive fluid from one side of the nip and to centrifugally accelerate that fluid. Generally there are two substantially radial surfaces, each positioned to receive fluid from an opposite side of the nip, i.e. one adjacent each side of the transfer ring. The or each radial surface generally takes the form of a disc. This disc may be a spherical segment disc having its concave face adjacent the transfer ring.

Use of the described apparatus results in tangential discharge of the fluid and so the apparatus will normally also include a secondary reservoir having an opening positioned to receive the tangentially discharged fluid, and the apparatus normally also includes means for transferring fluid from the secondary reservoir to the bearing or bearings on the shaft.

Preferably the second reservoir is positioned above the shaft, i.e. with the base of the reservoir above the bearings, in which event the means for transferring fluid from the second reservoir to the bearing or bearings may be gravitational feed.

The invention includes not only apparatus suitable for fitting on a shaft and also the shaft fitted with the apparatus, but also a method of lubricating bearings of a rotating shaft by fluid from an underlying reservoir by transferring fluid to the top portion of the shaft by a ring having its upper portions resting on the shaft and its lower portions entering the fluid in the reservoir and centrifugally accelerating a portion of the transferred fluid so as to tangentially discharge some at least of the transferred fluid from the shaft, generally in a direction above the shaft periphery, and generally collecting the discharged fluid in a secondary reservoir above the shaft and transferring the collected fluid to the shaft bearing or bearings.

Thus the invention provides a method and apparatus for effecting the automatic transfer of a predetermined quantity of lubricating fluid from a lubricating reservoir to one or more bearings supporting a high speed rotating shaft. The actual pick-up of lubricating fluid from the reservoir is accomplished by a large pick-up ring which merely rests on the rotating shaft and is frictionally driven by the shaft at a greatly reduced speed, thereby continuously bringing a film of oil on the ring's surfaces up to the top portion of the shaft. On each side of the pick-up ring there may be disposed a transfer disc which is corotatable with the shaft.The lubricating fluid which is squeezed out of engagement with the inner ring surface by the nip action of the upper portion of the shaft impinges upon the surface of such disc and is rapidly accelerated and discharged tangentially from the rotating disc into the mouth of a secondary reservoir which is disposed at a level above the lower level of the bearings supporting the rotating shaft. The accumulated lubricating fluid in the secondary reservoir may be permitted to flow by gravity into one or more of the bearings supporting the high speed rotating shaft, thereby automatically accomplishing the lubrication of the shaft bearings irrespective of the rbtational speed of the shaft or the height of the lubricating fluid maintained in the primary reservoir.

The invention is now described with reference to the accompanying drawings in which: Figure 1 is a perspective schematic view of a complete lubricating system embodying this invention for a high speed shaft mounted in an overlying relationship to a lubricating fluid reservoir.

Figure 2 is a partial vertical sectional view of the fluid transfer mechanism employed in the system of Fig. 1.

Figure 3 is a view similar to Fig. 2, but illustrating a modified configuration of the fluid transfer discs.

The apparatus schematically shown in Fig.

1 may be applied to the lubrication of conventional anti-friction bearings 5 which support a rotating shaft 10. The invention is of particular value for automatic lubrication of shafts rotating at speeds in excess of 5000 rpm.

The shaft 10 is disposed in overlying rela tionship to a lubricating fluid reservoir indicated schematically by the open top box 1 5.

A pool of lubricating fluid F is provided in the box 1 5. A transfer ring 20 is provided which -is of substantially greater diameter than the shaft 10 and is gravitationally supported on the shaft 10 so that the lower portions of the ring 20 enter the lubricating fluid F. The ring 20 will be frictionally rotated by the shaft 10 at a substantially lower speed than the rotational speed of the shaft 10 and will effect the upward transfer of a flim of lubricating fluid adhering to the surfaces of the transfer ring 20, particularly the inner cylindrical surface 20a.

On each side of the transfer ring 20 a fluid accelerating member 25 is secured in conventional fashion to the shaft 10 for co-rotation.

The accelerating members 25 may take any desired shape, but preferably the surfaces 25a thereof immediately adjacent to the transfer ring 20 are of generally radial configuration.

In this manner, the portions of fluid F carried upwardly by the transfer ring 20 and then displaced laterally by the nip formed between the inner surface 20a of transfer ring 20 and the shaft surface 10 will be squeezed axially into contact with the radial surfaces 25a of the fluid transfer members 25 and rapidly accelerated by such members since there travelling at shaft speed which is normally rotating at a speed of at least ten times the rotational speed of the transfer ring 20.

The portion of the fluid F thus transferred t6 the accelerating members 25 is rapidly centrifugally accelerated and discharged tangentially from the periphery of the accelerating members 25. A secondary reservoir 30 is provided, being mounted in any convenient fashion above the primary reservoir 1 5 and preferably having a bottom portion 31 which is at a higher level than the lowest bearirig surfaces of the bearings 5. Secondary reservoir 30 is provided with an open mouth hood portion 32 facing in the direction of discharge of fluid from the accelerating members 25.

The path of the discharged fluid is indicated by the arrows in Fig. 1.

It is therefore apparent that a portion of the lubricating fluid lifted by the transfer ring 20 to the top portions of the shaft 10 will be brought into contact with the rotating surfaces 25a of the accelerating members 25 and then tangentially discharged by such members into the hood 32, and hence will collect in the bottom of the reservoir 30. Any conventional means may then be provided for transferring the collected lubricant fluid from the secondary reservoir 30 to the bearings 5, such as gravity feed conduits 34.

As shown in Fig. 2 the fluid accelerating members 25 may take the form of a simple planar disc which is keyed or press fitted to the shaft 1 0. Alternatively, as illustrated in Fig. 3, the accelerating member 26 may,take the form of a pair of spherical segment discs having their concave surfaces 26a respectively disposed adjacent the sides of the transfer ring 20. This concave configuration helps to confine the centrifugally discharged fluid to a path lying between the discs 26 and hence permits a more rapid accumulation of lubricant ing fluid in the secondary reservoir 30.

Thus the invention provides a reliable continuous lubrication of the bearings of a rotating shaft 10 from a lubricating fluid reservoir which is disposed beneath the shaft. So long as the shaft 10 is rotating, some of the lubricating fluid will be transferred by the transfer ring 20 to the upper surface of the shaft 10 and then centrifugally accelerated by the accelerating members 25 and tangentially flung into the open mouth 32 of the reservoir 30. So long as lubricating fluid is collected in the reservoir 30, it will be automatically fed into the bearings 5 by the gravity conduits 34.

Claims (14)

1. An apparatus for lubricating a shaft bearing with fluid from a reservoir beneath the shaft, the apparatus comprising the reservoir, a ring that has a diameter greater than the shaft and that can be gravitationally suspended from the shaft with the lower portion of the ring passing through the reservoir so that, upon rotation of the shaft, the inner surface of the ring can carry fluid from the reservoir up to the nip between the inner surface and the shaft, and means for centrifugally accelerating at least a portion of the fluid carried to the nip and thereby tangentially discharging that fluid.

2. Apparatus according to claim 1 in which the means for centrifugally accelerating fluid comprise a fluid accelerator that comprises at least one substantially radial surface and that can be mounted on the shaft for corotation with the shaft with the or each substantially radial surface in a position to receive fluid from one side of the nip and to centrifugally accelerate the fluid.

3. Apparatus according to claim 2 in which the fluid accelerator comprises two substantially radial surfaces, each positioned to receive fluid from an opposite side of the nip.

4. Apparatus according to claim 2 or claim 3 in which the or each radial surface is a disc.

5. Apparatus according to any of claims 2 to 4 in which the or each radial surface is a spherical segmental disc having its concave face adjacent the ring.

6. Apparatus according to any preceding claim also including a secondary reservoir having an opening positioned to receive the tangentially discharged fluid.

7. Apparatus according to any of claims 1 to 5 comprising the shaft, at least one bearing on the shaft, the reservoir positioned beneath the shaft, the ring gravitationally suspended from the shaft with the lower portion of the ring passing through the reservoir, and the means for centrifugally accelerating fluid carried to the nip mounted on the shaft for corotation with the shaft.

8. Apparatus according to claim 7 including a secondary reservoir having an opening positioned to receive tangentially discharged fluid and means for transferring fluid from the second reservoir to the at least one bearing.

9. Apparatus according to claim 8 in which the second reservoir is positioned above the shaft.

1 0. Apparatus according to claim 9 in which the means for transferring fluid from the second reservoir to the at least one bearing comprises gravitational feed.

11. Apparatus according to claim 1 substantially as herein described with reference to any of the accompanying drawings.

1 2. A method of lubricating bearings of a rotating shaft by fluid from an underlying reservoir comprising transferring fluid to the top portion of the shaft by a ring having its upper portions resting on the shaft and its lower portions entering the fluid in the reservoir and centrifugally accelerating a portion of the transferred fluid and tangentially discharging some of the fluid away from the shaft.

13. A method according to claim 12 in which the tangentially discharged fluid is collected in a secondary reservoir and is transferred from this reservoir to the shaft bearings.

14. A method according to claim 1 3 in which the secondary reservoir is above the shaft bearings and transfer is by gravitational flow.