US 2626192 A
Description (OCR text may contain errors)
Patented Jan. 20, 1.953
OIL-POT FOR VERTICAL-SHAFT MACHINES Ren A. Baudry and Garfield E. Peterson, Pittsburgh, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 29, 1950, Serial No. 171,212
Our invention relates to bearing-assemblies for vertical-shaft machines, comprising a stationarily mounted oil-pot which has an inner standpipe around the shaft.
It has been found that there has frequently been oil-leakage down the vertical shafts of such machines, particularly in the high-speed machines. To discover the cause of this leakage, it was necessary to build a test-machine with transparent parts, so that the oil-circulation about the standpipe could be observed and studied. It was found that the runner which dips down into the oil in the oil-pot had a pumping-action, tending to throw out the oil centrifugally along the bottom face of the runner, and thus sucking the oil away from the inner diameter of the runner. This pumping-action drew out the oil from the space between the inner diameter of the runner and the outer diameter of the inner standpipe, depressing the oil-level at this place, down to the bottom of the runner, thus causing air to be sucked in, and in a few seconds all of the oil in the pot was transferred into foam and froth, which would buildup and leak out over the top of the inner standpipe.
Our present invention is directed to a provision of suitable seal ng-means for preventing the action just described. More particularly. it is an ob ect of our invention to provide a spaced sealing-ring, disposed in the space between the lower end of the inner diameter of the runner and the inner standpipe of the oil-pot, with means for providing a substantially free oil-communication from the main body of oil in the oil-not to the inner diameter of the sealing-ring at the bottom of said ring, and thence over the top of said ring, and also with means for impeding the downward flow of oil in the space between the outer diameter of the sealing-ring and the lower portion of the inner diameter of the runner.
With the foregoing and other objects in view, our invention cons sts of the machines, combinations, systems, parts, and methods of design and operation, hereinafter described and claimed, and illustrated in the accompanying drawing, wherein:
Figure 1 is the fragmentary vertical sectional view of the u per bearing-assembly having Kingsbury thrust bearings and a guide bearing,
showing the manner of use of our new sealingmeans;
Fig. 2 is a detail of the sealing-means which is used in Fig. l; and
Fig. 3 is a vertical sectional view of a guidebearing assembly for a vertical-shaft machine,
embodying our invention.
2 Claims. (Cl. 308-134.1)
Referring more particularly to Figs. 1 and 2, we have shown the top end of a vertical-shaft water-wheel generator, comprising a stator member which is represented by an upper bracket 4 which is shown fragmentarily at the bottom of Fig. 1, and a rotor member which is represented by the top end of a vertical shaft 5. The frame bracket 4 supports an oil-pot 6, which comprises an inner standpipe 1 and an outer standpipe 8, both mounted on top of the top plate 9 of the bracket 4. The inner standpipe l surrounds the shaft 5, with a small space therebetween.
The top end of the shaft carries a runnerbushing or thrust-block M. which rotates with the shaft. Secured to, and abutt ng up a ainst, the runner-bushing I4 is a runner 15, which is supported by resting on top of the thrust-bearing shoes i6, which are shown as being tiltably mounted on jack-screws I! which are supported b the top plate 9 of the bracket, which also constitutes the bottom plate of the oil-pot 5. A filling of oil is provided, in the oil-pot 6, up to a cold oil-level I8, which rises up to a hot oil-level [9, which is limited by the top of an overflow pine 20. The normal hot and cold oil-levels l9 and I8 occur at an intermediate point in the top-structure 23 which is provided for the oil-pot 6. This top-structure 23 also includes a seal 24 which cooperates with the outer periphery of the We may use only one of these seals.
Surmounting the top end. of the shaft 5 and the runner-bushing M, in Fig. 1, is a suitable cover 25.
The oil in the oil-pot 6 is cooled by suitable means, represented in the drawing by coolingcoils 26. Other well known details of oil-pots of this nature have been omitted, in the interests of clarifying the description of our present improvements.
In accordance with our present invention, we provide means for preventing oil-leakage in the space between the top of the inner standpipe I and the downwardly depending inner diameter of the runner I5. Our preferred form of means, which is used for taking care of the most stubborn cases of oil-leakage, provides two restricted spaces, or oil-seals, both disposed within the space between the standpipe 1 and the inner diameter of the runner l5. Under certain circumstances,
3 As shown more in detail in Fig. 2, we provide, in the space between the outer diameter of the inner standpipe I and the lower portion of the inner diameter of the runner IS, a spaced stationary sealing-ring 30. The upper portion of the sealingeringillhas a relatively small radialclearance if from the inner diameter of the runner IS. The inner diameter of the ring 30 has a larger radial clearance 32 from the outer diam-- eter of the inner standpipe I. The ring 30 also has a lower portion 33 which'extends below the bottom of the runner [5. The lower end of the ring 30 is in relatively free. communication withthe main body of oil in the oil-pot 6-, so that oil can freely flow under the bottom of the ring 30, up through the radial clearance. 32 at the inner diameter of the ring 30, and thence'over the "top of the ring, so as to feed oil freely to the top of the small radial clearance t.
This small radial clearance t between the ring 30-and the runner l acts as an-ioil-impedingrestricted-passage sealing-means for substantially impeding thedownward flow of oil in thespace between the outer diameter of the sealing-ring 30 :andthe lower portion .of the inner diameter of the runner l5- This'small radial clearance t isperhaps the simplest form of an oil-impeding. sealing-meansfonthis purpose. It will be understood, of course, that-other, or more elaborate, means. may be provided for the same purpose. This oil-impeding sealing-means t thus reduces the .rate of downward oil-flow .inthis space, .in response to the pumping-action of the runner l to-alrate which. considerably lower than the availablerate of .oil-supply in the free-communication spaceswhich. are .providedfrom .the main body ofoil .under, and back of, and over the top .of, the sealing-ring. 30.
Any suitablemeans may be provided for stationarily supporting the spaced sealing-ring 30, with or without some freedom of self-centering adjustment. In the specific form-of ourinvention which is shown in Fig. 2, this-means may be in theform of a few loosely fitting spacer-blocks 3.4.:and 34, at spaced points around the outer diameter and at the bottom. of the .innerstandpipe .1, with a loosely fitting pin or pins 34" for preventing rotation of the ring 30, while permitting the .ring to..center itself concentrically so-as to provide aiuniformirestricted gap t at all points around. it.
A second oil-impeding sealing-means? ispro- .vided, above the top of the sealing-ring .30. and below the normal oil-level [8 or |9..in theoil- ,pot' .6. Thissecondoil-impeding sealing-means. t?
sealing-ring 3.0,. and below the normal oil-level in the oil-pot. construction, this. second restricted radial clear- As amatter of. convenience in ance f is provided by a ring 35 which is secured .to the: outersurface of the-standpipe 1, .so as to constitute, ineffect, an enlargement. or shoulder on thestandpipe; However, this-ring or shoulder 35..might have been attached to the inner diameter. of the runner 15, so that the second restrictedradial clearance i would then'be providedbe- :tween the inner-diameter of the ring. .35 and The essential thing, ofcourse, is that some suitable means should be provided for substantially impeding the downward flow of oil in the space between the stationary standpipe I and the rotating runner l5.
In order for the restricted radial clearance t or t toserveproperly as-aseal, without "the formationof.'foam,.it is necessary'that' the rotating oil-flow in this clearance shall be laminar. This matter has been investigated and discussed by G. I. Taylor, in an article on The stability of a viscous liquid,"Transactions of the Royal Society of London, Series A, .volume 223, 1923, page 289, and Taylors conclusions have been verified by our ownexperiments. The limiting condition for laminar. flow in the-seal-gap t or t is the Reynolds number. In our tests, we have found that the critical Reynolds number is between 1000 and 1300,, and occasionally higher Reynolds numbers up to 1800 or 2000. Between these limits, we have sometimes found turbulent flow, and sometimes laminar flow, depending upon other conditions. For the most part, ifth-e Reynoldsnumber is below 1000, laminar flow'will be obtained; but, toprovide afactor of safety, a Reynolds numberiof' 800 represents a safer design-condition.
The Reynolds number NR may be calculated from the formula where t=the thickness of the gap or radial clearance, V =the speed or velocity of the innerdiameter-o'f the runner [5' or other rotating member, and r=the kinematic'viscosityof the oil.
If we set the maximum allowable Reynolds number Na at 1000, it will be readily seen that the-gap-thi'ckness of the-small radial clearance 12 or 1f must be smaller than l,0'00'1'/V. Ordinarily it will be found that this gap or small radial clearance t or i will be sosmall that it is desirable to use as'large a gap as possible, without running the risk of turbulent flow. A safe and preferable design-condition, therefore, would be to make this small radial clearance Z or t of the order of 800 r/V'. Gaps tof 0.04 to 0.16 inch are used in practical application of our invention to vertical generators.
' In the operation of our novel bearing-seal which is shown in Figs. 1 and 2, it will be noted that the pumping action of the runner I5; in tending to cause oil to flow radially away from the inner'diameter of said runner, cannot drain off allof the inner-space oil by drawing the oil downwardly in either one of the small radial spaces t or t, because provision is made for supplying oil freelyto the bottom of the top radial clearance t, or to the top of the bottom radial 'clearancet', faster than oil can be drawn downwardly through these seals. In this way, we prevent'the oil level inside of the inner diameter of the runner l5 'from'beingdropped to the bottom of the runner l5, and hence we prevent the formation ofthe'foa'm and'froth which has'previously resulted in occasions of oil-leakage over the top of the'inner standpipe I and thence down along the shaft 5.
In the form of our invention which is shown inFig. 3, the construction is similar,.except that the runner-bushing It and the runner [5 of Fig. '1 have been combined in a single integral runbearing is provided.
In Fig. 3, the inner standpipe 1 is spaced at all points by a considerable radial spacing from the inner diameter of the depending runnerportion 45, and the lower end of this radial spacing is occupied by a sealing-ring 30', which is supported on a few depending brackets 48 which are carried by the guide-bearing 41. The sealing-ring 30 is provided, as before, with a small radial clearance t with respect to the inner diameter of the depending runner portion 45, while a larger radial clearance 32 is provided between the sealing-ring 30 and the inner standpipe l.
The operation of the bearing-assembly shown in Fig. 3 is otherwise the same as that which has been described for Figs. 1 and 2, except that it will be noted that the second or upper oil-impeding sealing-means or restricted radial clearance t of Figs. 1 and 2 has been omitted, in Fig. 3, as being an unnecessary refinement, in this case.
While we have discussed our invention in connection with two illustrative forms of embodiment, we wish it to be understood that we are not limited to these particular forms, as various equivalents may be substituted, in place of the precise structures which we have illustrated, and also certain parts may be omitted or added, within the contemplated scope of our invention. We desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language.
We claim as our invention:
1. A bearing-assembly for a vertical-shaft machine, comprising a stationarily mounted oil-pot including an inner standpipe surrounding the shaft in spaced relation to the shaft, a bearingrunner, means for mounting the top part of said runner so that it is carried by the shaft and rotates therewith, the lower part of said runner being below the normal oil-level in the oil-pot, and a bearing cooperating with said runner, characterized by a spaced stationary sealing-ring carried by said oil-pot between the outer diameter of said standpipe and the lower portion of the inner diameter of said runner, below the normal oil-level in the oil-pot, means for providing relatively free oil-communication from the main body of oil in said oil-pot to the inner diameter of said ring at the bottom of said ring, and thence over the top of said ring, means for providing an oil-impeding restricted-passage sealing-means for substantially impeding the downward flow of oil in the space between the outer diameter of the standpipe and an intermediate portion of the inner diameter of the runner, below the normal oil-level in said oilpot and above the top of said ring, and means for providing an oil-impeding restricted-passage sealing-means for substantially impeding the downward flow of oil in the space between the outer diameter of the ring and the lower portion of the inner diameter of the runner.
2. A bearing-assembly for a vertical-shaft machine, comprising a stationarily mounted oil-pot including an inner standpipe surrounding the shaft in spaced relation to the shaft, a bearingrunner, means for mounting the top part of said runner so that it is carried by the shaft and rotates therewith, the lower part of said runner being below the normal oil-level in the oil-pot, and a bearing cooperating with said runner, characterized by a relatively large radial clearance between the lower part of the inner diameter of said runner and the outer diameter of said standpipe, and a relatively small radial clearance between a higher part of the inner diameter of the runner and the outer diameter of the standpipe, the bottom of said higher part being below the normal oil-level in the oil-pot, and a spaced stationary sealing-ring carried by said oil-pot within said relatively large radial clearance, said ring having an upper portion having a relatively small radial clearance from the inner diameter of said runner, all portions of said ring having a larger radial clearance from the outer diameter of said standpipe, as compared to said small radial clearances, the bottom end of said last-mentioned larger radia1 clearance being in relatively free communication with the main body of oil in the oil-pot, the top of said ring being well below the top of said relatively large radial clearance between the runner and the standpipe, and said ring having a lower portion extending below said runner.
RENE A. BAUDRY. GARFIELD E. PETERSON.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,798,204 Howarth Mar. 31, 1931 2,243,961 Howarth June 3, 1941