Bearings – Rotary bearing – Fluid bearing
Patent
1997-08-07
2000-07-04
Hannon, Thomas R.
Bearings
Rotary bearing
Fluid bearing
384121, F16C 3206
Patent
active
06082901&
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic axial bearing for a radially-supported rotatable shaft or axle.
There is a need within many fields of technology for an axially-adjustable bearing system, which can withstand heavy and variable axial thrust loads. One example of this is in the cellulose processing industry, where a multi-purpose axial mill can be subjected to thrust loads on the order of 100 tons, while at the same time having to satisfy high demands for accuracy in axial positioning, in order to achieve an exact grinding gap.
A similar axial bearing system is known from the PCT publication WO 88/03611, which contains a detailed description of the general requirements for a hydrostatic bearing system and hydrostatic axial-bearing systems of the prior art.
The axial bearing system mentioned in the PCT publication uses two hydrostatic axial bearings, one on either side of a flange-like pressure plate which is anchored to the shaft or is formed integrally with it. Another system is shown in SE 464 370, where two flanges are used instead of one, with the bearings acting in opposed directions, away from one another.
Both these designs have practical limitations, mainly in respect of the difficulty of maintaining the inner and outer sealing gaps at the same height in spite of deflections caused by loads and thermal expansion. A deviation as small as 1/100 mm can have disastrous consequences. In addition, the bearing is relatively heavy, with a high moment of inertia, which is a great disadvantage in absorbing vibrations of the flange. The bearing is also very expensive due to its weight.
SUMMARY OF THE INVENTION
The purpose of the present invention is to provide an hydraulic axial bearing arrangement without the drawbacks mentioned above, and with a higher loading capacity and lower energy losses.
According to the invention, an hydraulic axial bearing for a radially supported rotating shaft, has a fixed flange, a substantially axial sealing gap formed between the flange and an outer sealing ring, and an inner, substantially radial sealing gap formed between the shaft and an inner sealing ring confined in the bearing housing, and means for supplying hydraulic pressure medium to the cavity formed between the sealing gaps, to absorb the axial loadings applied to the axle. Preferably, two such bearings are provided, one on each axial side of the flange.
The advantages, compared to the systems in the previously-mentioned publications, will be evident to the professional in this field:
1. One axial sealing gap for each bearing, instead of two, will be insensitive to deviations and thermal expansion of the flange and bearings.
2. The pressurized medium for the cavities between the sealing gaps need not be supplied through the bearings.
3. The outer sealing ring has low mass, and consequently low moment of inertia, resulting in a closer adaptation to the vibrations of the flange.
4. An inner radial gap provides a larger utilized hydraulic area, which provides a higher loading capacity.
5. Energy consumption is lower, since the inner gap is closer to the center line.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a double-sided bearing arrangement as incorporated in the invention.
FIG. 2 shows an exposed and enlarged axial sealing ring, in which the pressure in the cavity is explained as a function of the geometry and the pressure applied to the pressure chamber by the pilot valve.
FIG. 3 shows an enlargement of the inner sealing ring, illustrating the drop of pressure of the medium along the radial gap.
FIG. 4 shows a practical application of a double-sided bearing arrangement according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
According to FIG. 1, the axle 1 or shaft is radially mounted or supported at a distance from one or both sides of a fixed flange 1a. In each of two axially opposed bearing housings, 4, 5, surrounding the flange 1a, there is an outer, axial sealing ring 2 and 3 respectively, which can be displaced within its outer pressure chamber, 4
REFERENCES:
patent: 1268575 (1918-06-01), Iskols
patent: 3146037 (1964-08-01), Hooker
patent: 4915510 (1990-04-01), Arvidsson
patent: 5219447 (1993-06-01), Arvidsson
patent: 5323972 (1994-06-01), Kjellqvist
Andritz Inc.
Hannon Thomas R.
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