GB2072043A - Centrifugal impact rock-crusher drive-shaft seal - Google Patents

Abstract

In a centrifugal impact rock crusher, having impellers to throw material against peripheral anvils, an oil seal 40 at the upper end of the pedestal 16, in which the drive shaft 12 is rotatably journaled, is located in a holder 32 having a grease passageway 48 which opens into a cavity above the oil seal whereby grease can be injected from a grease line 52 to provide a renewable grease barrier protecting the oil seal from abrasive rock particles. To assist in retaining the grease the cavity is fitted with an absorbent gasket 42 and is encircled by an upstanding annular sleeve 44 mating with an annular groove 46 in the hub 11 of a rotary table carried by the drive shaft 12. <IMAGE>

Description

SPECIFICATION Centrifugal impact rock crusher drive shaft seal The present invention relates to centrifugal impact rock crushers and is especially concerned with a seal arrangement for the drive shaft thereof.

Centrifugal impact rock crushers of the prior art typically have a vertical drive shaft arranged to drive a horizontal rotary impeller table on which are mounted several impeller shoes for throwing the material to be crushed off of the table against peripheral anvils where it is crushed upon impact.

Since the impeller components are themselves massive and in addition carry a large load of heavy rock, the drive shaft must generally be journaled in bearings which are continuously iubricated in order to provide a long-lived crusher. These bearings normally are mounted in a pedestal which surrounds the drive shaft and which provides a reservoir for oil lubricant that is circuiated through the bearings.

With this arrangement oil seals are provided at the top and bottom of the pedestal to seal the drive shaft against leakage of oil and to prevent foreign matter from contaminating the oil but the top oil seal in particular is quite susceptible to wear and damage.

The internal environment of crushers of this type includes large amounts of ground rock and rock dust which is very abrasive and yet is small enough so that it is difficult to screen mechanically from the operative portions of the crusher. Therefore, as the ground rock accumulates around and on top of the pedestal it tends to invade the upper oil seal thereby causing excessive wear and premature seal failure.

Because of this condition, the oil seal must be constantly monitored for wear and it must be frequently replaced to prevent the rock from damaging the bearings when the oil seal does fail. As a result considerable labor expense and down time are expended to prevent this occurance. In addition, due to the high abrasiveness of the rock and the quantity of it which builds up adjacent to the seal, often the seal fails unexpectedly, thereby causing bearing failure even though extensive preventive action is undertaken.

The present invention seeks to overcome the above-mentioned disadvantages and limitations of the prior art centrifugal rock crusher upper drive shaft oil seals and provides, at least in preferred embodiments, means for injecting grease into a cavity located above the oil seal from outside of the crusher without the necessity of terminating crusher operation. The grease then provides an easily renewable sealing barrier or buffer layer which prevents the crushed rock from reaching the oil seal.

In a typical embodiment of the invention, the seal provided in a rock crusher of the type referred to between the drive shaft and the pedestal, at or adjacent the upper end of the latter, comprises a seal holder which is press fit into the open top of the pedestal and through which the drive shaft extends.

The holder has a central cylindrical bore, having a larger diameter than the diameter of the drive shaft, for passage of the drive shaft, and an oil seal fits snugly into the space resulting between the holder and the drive shaft leaving a cavity above for receiving grease sealant. In order to absorb the grease and prevent its rapid dissipation, an annular felt gasket is placed on top of the oil seal. The grease is introduced into the seal through a plurality of orifices located on the inner wall of the holder after being passed through a grease passageway which extends through the upper portion of the pedestal and the seal holder. A grease line, which extends from the grease passageway to outside the crusher, has a fitting for attachment of a grease gun at its extremity.

In order to further prevent dissipation of the grease, the seal holder is also preferably provided with an upstanding annular sleeve which may be press fit into a notch located around the periphery of the central bore in the holder. This sleeve may be rotatably accommodated within a mating annular notch or slot which is located in the hub that mounts the impeller table at the top of the drive shaft. Such a seal can provide a long service life and eliminate the necessity of frequent termination of crusher operation for inspection and cleaning. Moreover, it need not require extensive redesign for installation in existing crushers, and it can be inexpensive to fabricate.

The invention will be further described with reference to the accompanying drawing which illustrates, byway of example, a preferred embodiment. In the drawings: Figure 1 is a fragmentary side elevational and sectional view, partially broken away to show hidden detail, showing the seal and structure at the upper end of the drive shaft of a centrifugal impact rock crusher according to this embodiment; Figure2 is a fragmentary detailed view, on an enlarged scale, showing a portion of the seal; and Figure 3 is a sectional view taken on the line 3-3 in Figure 1.

Referring to the drawing, the centrifugal impact rock crusher of which a portion is shown in Figure 1 is of the type having a rotating cylindrical table (not shown) mounted by a hub 11 fixed, such as by means of a key 14, to a table drive shaft 12. The drive shaft 12 is rotatably journaled within a tubular cylindrical pedestal 16 by upper and lower bearings 18 which are lubricated by a circulating oil system.

In the embodiment illustrated, the lower bearing 18 is submerged in oil 20 which is contained in the pedestal 16 and which is retained therein by a lower seal 22. Opening into the bottom of the pedestal and passing through seal 22 is an oil return channel 24 which is connected to the inlet of an oil pump (not shown) through an oil outlet line 26. The outlet of the oil pump is connected through an oil inflow line 28 to an oil inlet channel 30 which passes through the pedestal coincident with upper bearing 18. In the system illustrated, the oil 20 is not under pressure in the pedestal and is gravity urged through the line 26 to the oil pump.

In accordance with the present invention a seal, denoted generally by reference 10, is located in the pedestal 16 above the upper bearing 18 and serves both to prevent loss of oil out of the pedestal and to prevent foreign materials passing between the hub 11 and the shroud 31 which protects the pedestal from entering into the pedestal thereby contaminating the oil. The seal 10 comprises a cylindrical seal holder 32 which has an outside diameter arranged for a press fit into the upper end of pedestal 16.

Located in the outer wall of holder 32 is an outwardly facing O-ring groove 34 of rectangular cross-section which carries an O-ring 36, and the upper periphery of the holder extends radially outwardly to form an overhanging rim which positions the holder in the pedestal.

Passing centrally through the holder 32 is a cylindrical bore having a diameter which is greater than the diameter of the drive shaft 12 in order to accommodate a commercially available annular oil seal 40 snugly therebetween. Thereby, oil injected into the upper bearing 18 is retained in the pedestal and foreign material is prevented from entering the pedestal through its top. Located on top of the oil seal 40 is an absorbent felt annular gasket 42 which also fills the gap between the drive shaft 12 and the holder 32.

The upper inside corner of the holder 32 is notched and a tubular cylindrical sleeve 44 is press fit into the notch. Sieeve 44 has a length greater than the depth of this notch in the holder and, therefore, extends upwardly above the upper surface of the holder.

Accordingly, an annular groove 46 is provided in the underside of the hub 11 to receive the upwardly extending portion of the sleeve 44 and to permit relative rotation therebetween.

In orderto inject grease above the oil seal 40 and protect it from abrasive crushed rock, a grease passageway 48, which passes through the upper portion of the pedestal and through the seal holder 32, opens through a plurality of radially spaced orifices 50 (see Figures 2 and 3) in sleeve 44. In the embodiment illustrated, the orifices are positioned approximately intermediate oil seal 40 and gasket 42. A grease line 52 interconnects passageway 48 and injection means such as a conventional "zerk" type grease fitting (not shown).

In operation, grease is injected into grease line 52 so as to pass through passageway 48 in holder 32 and out of orifices 50 in sleeve 44. The grease then is absorbed into gasket 42 and flows around it to fill the gap between hub 11 and gaskets 42 and also the radially inwardly portion of groove 46. It will be noted that in addition to acting as a physical barrier for keeping foreign material away from seal 40, the sleeve 44 also serves to prevent the grease from being driven outwardly be centrifugal force when the drive shaft 12 is rotated.

The grease then acts as an additional seal to prevent the highly abrasive rock dust, which is being created in the crusher, from reaching oil seal 40 and causing it to prematurely wear out. As the grease becomes dissipated, more grease is added through line 52 to replace it and in the process wash any crushed rock or any other foreign matter away from oil seal 40. In addition to providing the necessary passageway for the grease, by extending grease line 52 outside of the shell of the crusher the grease can be introduced without the necessity of terminating crusher operations.

As a result, the life of the oil seal 40 is greatly increased and the likelihood of its being destroyed and admitting foreign material into the pedestal 20 where it will contaminate the oil and possibly destroy bearings 18 is greatly reduced.

It will of course be understood that many modifications in the precise structural details herein described may be made within the scope of the invention as defined in the appended claims and, in particular, there is no intention, in the use of descriptive terms and expressions, of excluding equivalents of the features shown and described or portions thereof.

Claims (8)

1. A centrifugal impact rock crusher having a drive shaft rotatably journaled within a pedestal provided with a seal at or adjacent its upper end for retaining lubricant and preventing ingress of foreign material between the pedestal and drive shaft wherein said seal comprises a seal holder which is fitted to the pedestal and which defines a central cylindrical bore extending axially therethrough for passage of the drive shaft, said bore having located therein oil seal means for sealing engagement with the drive shaft, and a grease passageway is provided which extends through said seal holder and opens into the bore above said oil seal means such that grease can be injected to provide additionally a grease sealing barrier over the oil seal means.

2. A centrifugal impact rock crusher as claimed in claim 1, wherein said grease passageway opens into said bore of the seal holder at a plurality of locations about the periphery thereof.

3. A centrifugal impack rock crusher as claimed in either of the preceding claims, wherein the grease passageway forms a continuation of a grease line which terminates at a grease injection point accessible externally of the crusher.

4. A centrifugal impact rock crusher as claimed in any of the preceding claims, wherein said seal also includes an annular grease absorbent gasket located within the bore of the seal holder adjacent and above said oil seal means such as to fill the space between the seal holder and drive shaft at that position.

5. A centrifugal impact rock crusher as claimed irl claim 4, wherein said grease passageway opens into said bore approximately intermediate said oil seal means and said absorbent gasket.

6. A centrifugal impact rock crusher as claimed in claim 4 or 5, wherein the seal holder includes an upwardly extending annular sleeve which encircles and extends above said absorbent gasket.

7. A centrifugal impact rock crusher as claimed in claim 6, wherein said upwardly extending annular sleeve of the seal holder projects into and is received within an annular slot on the underside of an overlying rotatable hub which mounts a table of the crusher on the upper extremity of the drive shaft.

8. A centrifugal impact rock crusher having a drive shaft rotatably journaled within a pedestal provided with a seal arranged substantially as herein described and illustrated with reference to the accompanying drawing.