Apparatus for lubricating a bearing assembly

A shaft is rotatably journalled in a bearing assembly. The shaft has a sleeve fixed thereon at a location axially adjacent to the bearing assembly, and a ring depends from the sleeve into a supply of liquid lubricant contained in an underlying sump. Rotation of the shaft and sleeve causes the ring to rotate about its own axis, and the rotating ring carries lubricant upwardly from the sump, with the thus carried liquid ultimately being returned to the sump by a combination of centrifugal and gravitational forces. A dam is interposed between the underside of the sleeve and the ring depending therefrom to direct a substantial and continuous flow of the returning lubricant to the bearing assembly.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to turbines and the like having shafts 
journalled for high speed rotation in bearings, and is concerned in 
particular with an improvement in the lubrication of such bearings. 
2. Description of the Prior Art 
In a conventional system for lubricating ball bearings, the lower portion 
of the bearing assembly is submerged in an underlying bath of liquid 
lubricant, e.g., oil. This produces satisfactory results at relatively low 
operating speeds. However, at higher operating speeds on the order of 
those encountered in turbine applications, severe problems are 
encountered. For example, the submerged bearing components churn and 
impart turbulence to the oil bath, and an increase in fluid friction 
within the bearing is experienced. This in turn results in excessive 
operating temperatures. Moreover, the turbulence in the oil bath causes 
oil to be thrown out through the seals, making it difficult to maintain 
the oil at an optimum level for efficient lubrication. 
In an attempt at avoiding these problems, the system shown in FIG. 1 has 
been developed for certain high speed turbine applications. Here the 
turbine shaft 10 is rotatably journalled in a ball bearing assembly 12 
enclosed in a housing 14. The housing has a base portion 16 which defines 
a sump 18 underlying the shaft, and a cap 20 which cooperates with a 
retainer portion 22 of the housing to hold the bearing assembly in place. 
The sump 16 is adapted to contain a supply 24 of liquid lubricant. In 
order to avoid excessive churning and frothing of the lubricant, the 
lubricant surface is maintained at a level beneath that of the rotating 
shaft and the rotatable bearing components. A sleeve 26 is fixed to the 
shaft at a location directly adjacent to the bearing, and a ring 28 is 
suspended from the sleeve. The ring 28 has a diameter considerably greater 
than that of the sleeve 26, and the lower ring portion dips downwardly 
into the liquid lubricant 24 in the sump. 
As the shaft 10 and sleeve 26 rotate, the frictional contact between the 
sleeve and the ring 28 causes the latter to rotate about its axis. 
Lubricant is carried upwardly from the sump by the rotating sleeve, and 
some of the thus carried lubricant ultimately finds its way to the bearing 
before being returned to the sump by centrifugal and/or gravitational 
forces. 
The difficulty with this arrangement is that the application of lubricant 
to the bearing is at best intermittent, somewhat haphazard, and thus 
relatively inefficient. Under high speed operating conditions such as 
those encountered in turbines and the like, reliability can be seriously 
compromised by the shortened bearing life resulting not only from 
inefficient lubrication, but more importantly from the insufficient 
dissipation of heat from the bearing assembly. 
The objective of the present invention is to overcome the above described 
problems by providing a more reliable and efficient means of continuously 
supplying lubricant to the bearing. 
SUMMARY OF THE PRESENT INVENTION 
The present invention provides a dam extending from the bearing into the 
space between the underside of the shaft mounted sleeve and that portion 
of the ring depending therefrom. The dam is appropriately configured and 
dimensioned to reliably direct a substantial and continuous flow of the 
returning lubricant to the bearing. 
Preferably, the dam constitutes an integral part of the bearing retainer, 
and includes a conical surface cooperating in radially spaced relationship 
with a conical surface on the sleeve to define an inlet passageway leading 
to the bearing. 
Advantageously, the inlet passageway is arranged to admit lubricant into 
the retainer on one side of the bearing, and the retainer is provided with 
an outlet opening on the opposite side of the bearing through which 
lubricant can exit from the retainer for return to the sump after having 
passed through the bearing.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENT 
A preferred embodiment of an arrangement in accordance with the present 
invention is depicted in FIGS. 2 and 3, where elements which are common to 
those of the prior art arrangement of FIG. 1 have been identified by the 
same reference numerals. 
According to the present invention, an arcuate dam 30 is interposed between 
the underside of the sleeve 26 and that portion of the ring 28 depending 
therefrom. The dam preferably comprises an integral part of the bearing 
retainer 22. 
The sleeve 26 has a centrally located cylindrical land 32 supporting the 
ring 28, with oppositely inclined surfaces 34, 36 extending axially and 
radially outwardly therefrom. The surface 36 cooperates in radially spaced 
relationship with an inclined surface 38 on the dam 30 to define an inlet 
passageway 40 for admitting lubricant into the retainer 22 on one side of 
the bearing assembly 12. The retainer has an outlet opening 42 on the 
opposite side of the bearing assembly 12. 
As the shaft 10 and sleeve 26 rotate, frictional contact between the sleeve 
and ring 28 causes the latter to rotate about its own axis. The rotating 
ring carries lubricant upwardly from the sump 18, and centrifugal and 
gravitational forces ultimately return the thus carried lubricant 
downwardly towards the sump. The dam 30 intercepts and diverts a 
substantial and continuous flow of the returning lubricant through inlet 
passageway 40 to the bearing assembly 12. The flow of lubricant into and 
through the passageway 40 to the bearing assembly causes a slight build up 
of lubricant on one side of the bearing assembly as at 44. From here, the 
lubricant continues flowing axially through the bearing assembly and then 
exits from the bearing retainer via outlet opening 42 for ultimate return 
to the sump 18. 
This continuous supply of lubricant to the bearing assembly is extremely 
advantageous, not only because it provides improved lubrication of the 
rotating bearing components, but also because it removes more heat from 
the bearing assembly and thus significantly lowers operating temperatures. 
The net result is a significant increase in bearing life, which is 
achieved without unduly complicating the lubrication system. 
Preferably, the housing cap 20 includes a radially inwardly protruding 
portion 46 having a partly cylindrical land 48 and oppositely inclined 
conical surfaces 50, 52 which cooperate in closely spaced relationship 
with the conical surfaces 34, 36 on the sleeve 26 to maintain the ring 28 
seated on the cylindrical sleeve land 32.