Bearings – Rotary bearing – Hydraulic or pneumatic bearing support
Patent
1989-05-01
1990-04-10
Footland, Lenard A.
Bearings
Rotary bearing
Hydraulic or pneumatic bearing support
384121, 384448, F16C 3206
Patent
active
049155105
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The present invention relates to a hydrostatic thrust bearing system for a radially journalled axle or shaft provided with a pressure plate or collar, the thrust bearing system having an external configuration which enables the system to be mounted around the rotatable axle and including a hydrostatic thrust bearing on each side of the pressure plate, and in which system each of the thrust bearings incorporates at least one oil pocket to which hydraulic fluid is fed from a hydraulic fluid source, preferably a constant flow pump.
STATE OF THE ART
Thrust bearings of this kind intended for taking up large axial forces are to be found in many technical fields.
One technical field in which such thrust bearings are used is found in the fibre beating mills of the paper industry, in which mills axial forces in the order of five tones or more can be generated in the beating process, even in mills of modest dimensions, and which also vary during the beating or pulping process.
For the purpose of maintaining a beating gap of predetermined width, the journalling problems are normally solved by arranging the radial bearings of the shaft or axle in a bearing box or a bearing package and then adjusting the whole of the bearing package axially with the aid of hydraulic systems in dependence on the axial loads that occur, in order to adjust the beating gap.
There is normally used in this regard a servo value which is in direct contact with the bearing package. The servo valve ensures that the beating gap can be adjusted smoothly and continuously to a tolerance of 1/100 mm while the beater is in operation, despite large variations in axial loads.
Also known to the art is a combined hydrostatic/hydrodynamic bearing system for beating apparatus in paper manufacturing mills, in which the two end surfaces of a collar provided on a shaft or axle constitute piston surfaces which work in a surrounding pressure chamber in a manner to enable the collar, and therewith the shaft, to be moved axially in the pressure chamber (see Wo 86/01434-Sunds Defibrator).
Variations on the axial load on the shaft are counteracted by means of compensatory fluid pressure on the end surfaces of the piston, such as to maintain a beater gap of predetermined width.
This publication, however, does not teach a hydrostatic bearing of the kind to which the present invention relates, i.e. a hydrostatic bearing which includes an oil pocket which exhibits an inner and an outer two ends annular sealing gap and has a constant leakage flow. In the case of this known bearing system, the radial gap between the chambers defined by the piston always has a constant width.
Various further types of hydrostatic bearings are known to the art. One essential characteristic of a hydrostatic bearing is that it is dependent on the supply of fluid from an external pressure source. This external pressure source ensures that metallic contact is avoided under all circumstances when the fluid supplied is evacuated through leakage or sealing gaps located in peripheral parts of the bearing.
Prior art hydrostatic bearings include so-called ring chamber bearings which are located opposite one another and which are mounted with a pre-set gap width. Consequently, a great deal of precision is required when fitting the bearings.
DE-A-2 357 881 (Mannesmann-Meer AG) teaches a hydrodynamic thrust bearing provided with a flanged pressure plate against which a plurality of slide shoes are urged by means of hydraulic pistons. These slide shoes move over an oil film having a thickness of between 0.008 and 0.012 mm. This oil film is created in a manner similar to that employed in other well known slide bearings, i.e. the film is built up between the two bearing surfaces as a result of the relative movement therebetween. The thickness of the oil film is therewith contingent on the speed at which the shaft or axle rotates and has no lubricating or carrying function when the axle is stationary.
In the case of these known hydrodynamic bearing systems the separate hydraulic piston
REFERENCES:
patent: 4239300 (1980-12-01), Adler
patent: 4643592 (1987-02-01), Lewis et al.
patent: 4652148 (1987-03-01), Olasz
patent: 4696585 (1987-09-01), Swearingen
Cellwood Machinery AB
Footland Lenard A.
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