Bearings – Rotary bearing – Antifriction bearing
Patent
1989-07-20
1990-04-10
Levy, Stuart S.
Bearings
Rotary bearing
Antifriction bearing
384611, 384517, 384454, 418203, F16C 3904, F04C 2900, F01C 2102
Patent
active
049155148
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a rotary machine equipped with a thrust balancing arrangement.
A machine of this kind comprising two helical rotors which are journalled in thrust bearings at both ends thereof is known from U.S. Pat. No. 3,388,854. In order to obtain uniform distribution of the load on the thrust bearings and a long useful bearing life, while avoiding the transition to larger bearings--which normally presents a problem due to the lack of space for accommodating bearings of larger diameter--the known machine is provided with a thrust balancing arrangement comprising a piston-cylinder device which under the influence of pressure fluid contingent on one working condition of the machine exerts an axial thrust on one rotor through the thrust bearing on the low pressure side of the machine. This axial thrust is exerted in a direction opposite to the direction in which the working fluid acts and also in an opposite direction to the bias of a spring means acting on the thrust bearing.
The length of the useful life of the machine depends upon the condition of the thrust bearings. The bearings need to be inspected at regular intervals and must be changed when necessary. A bearing change is difficult to carry out and requires skill and experience on the part of the engineer concerned. For example, when effecting a bearing change it is necessary to dismantle the thrust balancing arrangement, together with associated connections and seals, and then to reassemble the thrust balancing arrangement and test the efficiency of the seals, which involves further work and also the risk of faults occurring as a result of dismantling the thrust balancing arrangement, etc.
OBJECT AND SUMMARY OF THE INVENTION
The object of the present invention is to provide a machine of the aforementioned kind in which the thrust balancing arrangement is constructed in a manner which will enable the thrust bearing to be checked and changed without undue difficulty, and which will extend the useful life of the thrust bearings.
This object is achieved in accordance with the invention with a machine having the characteristic features set forth in the following claims.
The fact that the auxiliary thrust bearing is located on the extremity of the shaft journal and is clamped resiliently between the thrust balancing arrangement and the spring means, enables the thrust bearing to be checked and changed easily, even by unskilled workmen. The relative ease with which the auxiliary bearing can be replaced can be utilized suitably by placing a relatively heavy load on the auxiliary thrust bearing and by lessening the load on the remaining bearings to a corresponding extent, therewith prolonging the useful life of the bearings. The auxiliary bearing on the other hand, enjoys a shorter useful life. This is of minor importance, however, since the auxiliary bearing can be readily changed, for instance when carrying out routine maintenance service.
The auxiliary thrust bearing may also be active when starting and stopping the machine, when the working fluid is under no pressure, or only a slight pressure, i.e. at low speeds which result in unproportional wear on the bearing. This is a further reason as to why it should be easy to replace the auxiliary thrust bearing.
According to one preferred embodiment of the invention, the annular piston-cylinder device of the thrust balancing arrangement has the form of a "plug-in" unit, therewith enabling said device to be readily removed and replaced without risk of causing a leakage as a result thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail with reference to exemplifying embodiments thereof illustrated in the accompanying schematic drawings, in which:
FIG. 1 is a side view of a machine constructed in accordance with the invention;
FIG. 2 is a longitudinal, sectional view of the bearing arrangement on the high-pressure side of the machine; and
FIG. 3 is a part sectional view showing a modification to the auxiliary bearing illu
REFERENCES:
patent: 1279574 (1918-09-01), Morris
patent: 3222991 (1965-12-01), Bone
patent: 3388854 (1968-06-01), Olofsson et al.
patent: 4730995 (1988-03-01), Dewhirst
Battista, Jr. William G.
Levy Stuart S.
Svenska Rotor Maskiner AB
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