Bearing lubrication device

A bearing lubrication device for use in ring-oiled journal bearings and the like in which a generally circular ring member is eccentrically disposed around the rotatable shaft in the bearing assembly. The ring has an outer surface, right and left sides extending downwardly from the outer surface at a predetermined angle, most preferably about 30 degrees, for a predetermined distance and then radially inwardly, generally perpendicular to the outer surface for a predetermined distance, and an inner surface, said inner surface having at least one, but preferably a plurality of grooves therein. As rotation occurs at high forward speeds, improved lubricant delivery, stability of operation and bearing performance capability are realized.

BACKGROUND OF THE INVENTION 
Oil rings are extensively used as conduit means for carrying oil or other 
lubricant from a reservoir to moving members, such as journal bearings, 
shafts, and the like. In operation, the oil ring is normally loosely 
disposed around the shaft and rotates as the shaft rotates, through 
contact with the shaft. Lubricant is carried from a sump or reservoir to 
the shaft, in the contours or grooves of the oil ring and by frictional 
attraction as the ring moves through the reservoir. The lubricant is 
deposited on the shaft or other member through the gravitational, 
frictional, and centrifugal forces inherent in the operation. Under 
conditions of slow rotation, the gravitational and frictional forces 
generally deliver a sufficient supply of lubricant; however, at higher 
velocities, which can be as high as 3000 to 4000 ft./min., the oil ring is 
either moving too fast for gravity to effect dispersion of the oil, or the 
centrifugal force on the ring and the oil is too great to overcome, and 
the oil either remains on the ring or is thrown outside of the rotational 
field. Thus, the lubricant does not reach the desired area, resulting in 
early wear and possible failure of the shaft, bearing, oil ring, or other 
associated members. 
Rotation of the oil ring depends on a propulsive force developed between 
the rotating shaft and the ring. As speeds increase, a fluid film is 
developed, and the driving force is transmitted to the ring by this 
lubricant film. The situation is analogous in many ways to that in a 
floating ring bearing and, without a direct drive mechanism, a slippage 
occurs. Prior attempts to develop a higher frictional coefficient and, 
thus, a more positive drive mechanism, have focused on modification of the 
cross-sectional geometry of the ring, including both inside and outside 
surfaces of the ring. Such prior ring structures have included T-shaped 
rings where the cross of the T serves as the inside surface, rings having 
a generally trapezoidal cross-section where the inner ring surface is 
planar, and rings having a generally trapezoidal cross-section where the 
inner ring surface contains a single wide groove thereacross. 
Factors opposing rotation of the ring are the drag on the lower portion of 
the ring which is submerged in the lubricant reservoir, the force required 
to lift the lubricant from the reservoir toward the top of the journal, 
and the frictional drag on the ring applied by close-running stationary 
surfaces, such as the sides of the ring slot in the bearing. Other factors 
affecting lubricant delivery include the composition of the ring and the 
viscosity of the lubricant used in the bearing. In addition, since a 
conventional oil ring rests on the upper surface of the shaft during 
operation and during periods of non-use, much wear results from the 
contact alone. When at rest, most of the lubricant drains back into the 
reservoir and very little lubricant protection is available for the 
start-up operation. Thus, until the lubricant film is re-established, 
early wear of the shaft, ring, bearings, and other associated members is 
likely to occur. This, in turn, leads to repair and replacement expenses, 
and the concomitant loss of operating time. 
SUMMARY OF THE INVENTION 
It is, therefore, one of the principal objects of the present invention to 
enhance the lubricating ability of oil rings, thereby increasing the 
capability and the capacity of thrust and journal bearings, by providing a 
bearing lubrication device having an oil ring configured to afford a 
greater oil delivery to the shaft and bearings, even at high rotational 
speeds. 
A still further object of the present invention is to provide an oil ring 
which is usable with most or all devices currently employing conventional 
oil rings, and which is economical to produce and to use. 
Yet another object of the present invention is to provide an improved oil 
ring that is stable at high operating speeds with superior oil delivery. 
These and other objects are attained by the present invention which 
generally relates to a bearing lubrication device for use in ring-oiled 
bearings and the like, which has a rotatable shaft, a bearing surface, a 
lubricant reservoir, and a generally circular ring member eccentrically 
rotatably received about said shaft for carrying lubricant from the 
reservoir for deposition on the shaft and the bearing surface. The ring 
member, preferably metal rotates with the shaft, and is constructed for 
stable operation at high rotational speeds with superior lubricant 
delivery than was possible with the conventional oil rings. 
More specifically, the improved oil rings according to the present 
invention comprise an outer surface, right and left sides that angle from 
said outer surface at a predetermined angle, for a predetermined distance 
and then angle radially inwardly, generally perpendicular to said outer 
surface, and an inner surface that has at least one, though preferably a 
plurality of grooves therein. 
Preferred oil rings according to the present invention, have a particular 
size and weight with a plurality of grooves being provided in the inside 
ring surface. Optimum unit weight for present oil rings from a standpoint 
of oil delivery and ring stability ranges from about 0.131 to about 0.142 
pounds per inch of circumferential length. Relative inner diameter of the 
ring to outer diameter of the journal should be from about 1.5 to about 
2.0, and preferably about 1.7. Further, the right and left angled side 
walls preferably define an angle from the upper surface in a range of from 
approximately 25 degrees to approximately 35 degrees and most preferably 
approximately 30 degrees. Moreover, the perpendicular side wall portions 
preferably should have at least a predetermined length. 
Various other objects and advantages of the present invention will become 
apparent from the below description, with reference to the accompanying 
drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now more specifically to the drawings, and to FIGS. 1 and 2 in 
particular, numeral 10 designates generally the bearing lubrication device 
embodying the present invention. The device is shown here disposed in a 
journal bearing 12, although its application is not limited in any way 
thereto. The assembly can normally be used wherever conventional oil rings 
are used for lubrication purposes, and in a variety of different devices. 
In normal operations with bearings of the type shown, an oil ring 19 is 
loosely, eccentrically disposed around a rotatable shaft 14, and rotates 
therewith in a manner to be explained below. Oil ring 19 rotates in a ring 
slot 16 located in a bearing member or liner 40, through a lubricant 
reservoir 18 and, as rotation occurs, carries lubricant from reservoir 18 
upwardly for deposition on the shaft and the bearing surfaces. 
A most preferred oil ring embodiment according to the present invention is 
illustrated in FIGS. 2 and 3. As thus illustrated, ring 19 has an outer 
surface 20, right and left side portions 21, 22, that taper outwardly from 
outer surface 20 an angle .alpha., and right and left vertical side 
portions 23, 24, that are of a predetermined length and are generally 
perpendicular to outer surface 20. Ring 19 further has an inner surface 25 
that defines a plurality of circumferentially extending side-by-side 
grooves 26 therein. 
A second oil ring embodiment 119 according to the present invention is 
illustrated in FIG. 4. Ring 119 has an outer surface 120, right and left 
side portions 121, 122 at an angle .alpha. as shown in FIG. 3, generally 
vertical side portions 123, 124 and an inner surface 125. Inner surface 
125 of ring 119 is shown to have a plurality of circumferential grooves 
therein, including a central groove 127 with outer, narrower grooves 126 
along opposite sides of same. 
FIGS. 5 and 5a illustrate yet another embodiment of the oil ring of the 
present invention. Ring 219 has an outer surface 220, side portions 221, 
222 at a predetermined angle .alpha., perpendicular side portions 223, 224 
and an inner surface 225. Inner surface 225 has a plurality of grooves 226 
therein and located therearound which, as shown in FIG. 5a, are transverse 
to the circumference of ring 219. 
FIGS. 6 and 6a likewise illustrate an oil ring 319 having generally 
transverse grooves 326 around an inner surface 325. Grooves 326 are, 
however, V-shaped with the legs of the V being at an angle .beta. of 
approximately 135 degrees. 
With oil rings of the present invention, the relative angle .alpha. of 
angular sides 21, 22 in conjunction with the length of vertical sides 23, 
24 have the greatest impact on oil delivery, particularly, as angle 
.alpha. of sides 21, 22 approaches zero degrees (0.degree.), side drag of 
ring 19 in ring slot 16 approaches maximum. Such causes the ring to 
operate erratically due to the greater side drag, and oil delivery is 
reduced due to insufficient ring speed. Conversely, as angle .alpha. of 
sides 21, 22 is increased, consequently shortening the length of vertical 
sides 23, 24, oil delivery increases accordingly and the lubricant is 
thrown off the ring by the rotational forces in the form of a splash or 
spray. Through experimentation, angle .alpha. for angular sides 21, 22 has 
been determined to preferably range from about 25 degrees to about 35 
degrees and most preferably is approximately 30 degrees, regardless of the 
diameter of the ring or the depth of the inside grooves 26. 
Through experimentation it has also been determined that the length of 
vertical sides 23, 24 relative to angle .alpha. may be controlled for 
improved oil delivery dependant upon journal speed ranges. Shorter 
vertical side dimensions are preferred for low journal speeds, while 
longer vertical sides are preferred for the higher journal speed ranges. 
Also it has been determined that vertical side lengths less than one 
millimeter produced wear and unstable operation at low journal speeds. 
FIG. 8 generally represents a curve of oil ring behavior over a range of 
journal speeds and depicts relative oil delivery by the ring through four 
regimes, I, II, III and IV. Curve N.sub.R represents ring rotational 
frequency, Q.sub.R oil delivery, and R.sub.O, ring oscillation. In regime 
I, at low journal speeds, oil ring 19 follows the journal at approximately 
the same peripheral speed. As the speed of shaft 14 increases, a 
transition point is reached at the end of regime I where, a hydrodynamic 
lubricant film begins to form. Ring speed at this transition point is 
considered to be the primary speed of the ring with respect to the journal 
speed. Primary speed of the oil ring is a combined function of the ring 
weight, shape, projected areas of contact, journal speed, lubricant 
viscosity, and localized temperature. 
As journal speed increases into regime II, thus increasing the speed of the 
ring above the primary speed, formation of the hydrodynamic lubricant film 
causes ring slippage accompanied by a corresponding decrease in oil 
delivery. Upon establishment of a full hydrodynamic film between the 
journal and ring, further increase in journal speed is followed by 
increased ring speed and oil delivery to a maximum oil delivery for the 
ring. Maximum oil delivery occurs at the end of regime II where the actual 
rotating speed of the ring is a balance between the propulsive force at 
the region of contact between the ring and the journal and the resistive 
force of the lubricant drag on the ring, and is designated as the 
secondary speed. The secondary speed is also a function of many 
parameters, including journal speed, oil viscosity, ring submersion level, 
and ring shape. For example, the greater the length of vertical sides 23, 
24 the lower the secondary speed. 
Moving into regime III, a significant decrease in ring speed and oil 
delivery are observed. Coincidentally in regime III, it is noted that 
significant ring oscillation (curve R.sub.O) is present. Ring oscillation 
in the plane of ring rotation actually begins to appear during the 
trailing portion of regime II, and though ring speed drops only slightly, 
oil delivery drops drastically in regime III, asymptotically approaching 
zero. Ring speed in regime III is referred to as tertiary speed and is 
believed to be the first rigid-body, critical speed of the ring. 
In regime IV oscillating vibrations abate while conical vibrations (angular 
with respect to the shaft) and translatory vibrations (lateral with 
respect to shaft) begin, (curve R.sub.CT) with frequency of both being 
that of ring rotational frequency or speed. Throughout regime IV, oil 
delivery remains essentially zero, resulting from oil splash and throw-off 
from the surface of the ring and partly also from the journal or shaft. 
Hence, above the tertiary speed regardless of journal speed, the 
rotational speed of the ring either remains constant or falls. Several 
specific factors influence this tertiary speed, including the ring shape, 
the ring-bore configuration which strongly controls the hydrodynamic 
stiffness of the ring, the weight or mass of the ring, and the ring 
diameter; for example, a larger ring has a lower tertiary speed. The 
effects of changes in lubricant viscosity on ring speed and lubricant 
delivery were also studied using lubricants of SAE 10, 20 and 30 weight, 
and it was found that though viscosity affected the primary and secondary 
speeds of the ring, tertiary speed was found to be independent of 
viscosity. 
Various materials may be used in the fabrication of oil rings according to 
the present invention, including brass, Muntz (60% Cu, 40% Zn), and bronze 
(SAE-660). Tests conducted on these materials using lubricant SAE 10 at 
120.degree. F. and a ring submersion level at 15% of the ring diameter, 
indicated that bronze attained an oil delivery approximately 10% higher 
than the others tested. Tests of the wear properties, consisting of 30,000 
start-stop cycles and 7,200 hours of continuous running at 1800 rpm, with 
lubricant SAE 10, indicated less wear with the brass ring, but differences 
were slight. 
Referring back to FIG. 2, oil ring 19 is shown disposed eccentrically 
around shaft 14 with contact made at the top of shaft 14. Shaft 14 is 
rotatable in bearing member or liner 40, which may be of any suitable type 
and, in the embodiment shown, rotation is in the direction of the arrow. 
Ring 19 assumes approximately the position shown in FIG. 2 when the 
apparatus is at rest, thereby allowing the outer edges of ring 19 to 
contact shaft 14. As rotation of the shaft and ring occurs, lubricant is 
carried upwardly from reservoir 18 by inside grooves 26 where it is 
deposited on shaft 14. 
In copending application Ser. No. 06/569,526, the oil ring of FIGS. 1 and 4 
is described in conjunction with a cantilevered leaf scraper, along with 
certain information demonstrating improved oil delivery over the use of 
such an oil ring per se. While such is true, the improved oil rings of the 
present invention achieve improved results without a stabilizer over prior 
oil rings. Such results are graphically demonstrated in FIG. 7. 
Particularly, in FIG. 7, graph 1 represents a commercial oil ring having a 
trapezoidal cross-section with a single wide groove along an inner surface 
of same, referred to as a Wulfel ring. Graph 2 represents a commercial oil 
ring having a T cross-section where the cross of the T provides an inner 
ring surface. Graphs 3, 4, 5 and 6 are representative of the oil rings of 
the present invention as illustrated in FIGS. 3, 4, 5 and 5a, and 6 and 
6a, respectively. As can be seen, all of the instant oil rings performed 
significantly better than the prior art rings across the shaft speed range 
shown. Further, rings of the present invention not only exhibit superior 
lubricant delivery, but also, maintained stable operation beyond 2000 rpm. 
The effects of varying the depth of groove on lubricant delivery for 
various shaft speeds was determined as set forth in copending application 
Ser. No. 06/569,526 and is incorporated herein by reference. Three rings 
of the embodiment shown in FIG. 4 were tested and were identical, except 
for the variance in inside groove depth where groove depth was 1.05 mm, 
1.52 mm, and 3.20 mm. From this data, an optimum depth of approximately 
1.52 mm was selected, providing approximately twice the oil delivery of 
rings having shallower or deeper grooves. The effects of variance in 
lubricant viscosity were determined based on experiments conducted with 
lubricants having SAE ratings of 10, 20, and 30 weight. Results indicated 
that the heavier lubricants showed marked increases in oil delivery, an 
important and desirable factor, especially in large bearing applications 
where the use of heavier lubricants and higher speeds are common. 
It will be understood, of course, that while the form of the invention 
herein shown and described constitutes a preferred embodiment of the 
invention, it is not intended to illustrate all possible forms of the 
invention. It will also be understood that the words used are words of 
description rather than of limitation and that various changes may be made 
without departing from the spirit and scope of the invention herein 
disclosed.