RU2282067C1 - Supporting-thrust slider bearing for shaft of turbomachine - Google Patents

Abstract

FIELD: production of supporting-thrust slider bearings preferably used for rotors of steam turbines and turbo-generators of average and high power.

SUBSTANCE: supporting-thrust slider bearing has casing consisting of upper and lower half circles, upper and lower supporting half inserts with supporting spherical surfaces, said half inserts being mutually engaged with inner bore of half rings of bearing casing, working and mounting shoes, inner annular channel provided in upper and lower half inserts, lubricant feeding and discharge grooves for working and mounting shoes, and oil seal unit. Upper and lower supporting half inserts with supporting spherical surfaces are positioned in spaced relation therebetween. In lower half ring of bearing casing there is channel for feeding lubricant under high pressure from independent outer source through feeding unit comprising back valve, as well as from internal source through two inner cross channels connected to pockets provided on spherical supporting surface of lower half ring of bearing casing. Basic feeding of lubricant onto supporting surface of lower supporting half ring is provided through channels arranged at an angle to horizontal plane of detachment of supporting half inserts and connected to inner annular channel, and feeding of lubricant to working and mounting shoes from inner annular channel is provided through upper as well as lower supporting half inserts via radial-axial channel system. Cooling of working and mounting shoes and discharge of used lubricants from spaces between disks of rotor and from spaces between shoes of supporting-thrust bearing are performed using system of radial and tangential channels provided in lower and upper supporting half inserts. Discharge of used lubricant from supporting members of supporting half inserts is provided through radial-end bevels formed at two sides of supporting surface of supporting half inserts, as well as radial channels formed on supporting spherical surface of supporting lower half insert, near region wherein lubricant is discharged from bearing layer of hydrodynamic wedge.

EFFECT: optimal conditions for self-adjustment of supporting-thrust bearing, optimized thermal mode, enhanced reliability of vibration conditions and increased bearing capacity of supporting-thrust bearing with all operating modes.

4 cl, 4 dwg

Description

The present invention relates to the field of power engineering, specifically turbine engineering, in particular to the production and operation of thrust plain bearings used for rotor shafts of steam turbines and medium and high power turbogenerators.

Known designs of thrust bearings containing the upper and lower half-shells with spherical bearing surfaces and an inner annular channel for supplying oil, from which lubricant enters the support elements and to the working segments, while there is no oil supply to the mounting blocks (segments). (Serezhkina L.P., Zaretsky E.I. "Axial bearings of powerful steam turbines" M., 1988, p. 37-38).

The reasons that impede the achievement of the technical result indicated below when using the known device include the lack of oil supply to the mounting blocks, and the spherical supporting surfaces of the bearing housing and half-shells are made without a gap between them.

Known designs of support-thrust bearings, containing the upper and lower half liners with spherical bearing surfaces made with small or zero interference, containing an inner annular channel for supplying lubricant to the supporting elements, as well as to the working and installation pads located in the upper and lower half liners wherein the supply of lubricant is made in the support element through a recess in the annular channel located in a horizontal plane from the side opposite to the direction of rotation of the shaft. (Trukhniy A.D., “Stationary steam turbines and turbine units” M., 1990, p.118, 125, 135).

The reasons that impede the achievement of the technical result indicated below when using known devices include the fact that the supporting spherical surfaces of the half-shells and the bearings of the bearing housing are made without gaps between them, which does not allow the insert to move relative to the rotor shaft in case of distortions of the bearings of the working cylinder bodies steam turbine, while the supply of lubricant to the installation pads is carried out only in the lower half liner. The noted drawbacks do not allow ensuring the uniformity of the temperature field of all the pads and the supporting element of the liner.

The closest device for a similar purpose to the proposed combination of features and selected as a prototype is the device of a thrust plain bearing containing a bearing housing consisting of their upper and lower half-shells, upper and lower half-shells with supporting spherical surfaces made mutually conjugated with the inner bore half-shell bearing housings, working and mounting pads, inner annular channel made in the upper and lower half-shells, by means of orogo lubricant is guided as a working blocks disposed in upper and lower semiloose leaves and to mounting blocks mounted only in the lower semiloose leaves, the supply lubricant to the bearing part semiloose leaves is formed through a recess in the horizontal plane, located on the side opposite to the rotation direction of the shaft. (Trukhniy A.D., Lomakin B.V. Heat-producing turbines, M .: 2002, p. 114).

The reasons that impede the achievement of the desired technical result when using the known device adopted for the prototype include the fact that in the device according to the prototype, the coupling of the spherical bearing surfaces of the half-shells and the half-shells of the bearing housing is made with insufficient clearance, which does not allow for free movement of the bearing relative to the rotor shaft. As a result of this, a uniform distribution of the temperature field of the working surfaces of the thrust bearing is not achieved at nominal and increased specific loads arising, for example, from thermal misalignment of the rotor shaft of a steam turbine rotor or distortions of the bearings of the working cylinder bodies. The absence of an additional supply of high-pressure grease to the spherical bearing surfaces of the half-shells limits the possibility of moving the bearing due to increased friction and wear between the contact bearing surfaces of the bearing, which leads to a decrease in the bearing capacity and, accordingly, the vibration reliability of the operation of the thrust bearing as a whole. The known device also does not allow to provide optimal conditions for cooling the working surfaces of the supply of fresh and exhaust waste lubricant for both persistent working and installation pads, and the supporting part of the half-liners. The latter leads to an undesirable uneven distribution of the temperature field on the working surfaces of the thrust bearing and, as a result, to a decrease in their bearing capacity and reliability.

The desired technical result is to ensure optimal self-alignment of the thrust bearing in the longitudinal direction relative to the shaft line at all steam turbine operating modes, optimizing the thermal conditions, increasing the vibration reliability and bearing capacity of the thrust bearing, reducing the consumption and loss of lubricant, as well as power loss friction turbomachines, which together will provide a noticeable improvement in the technical and economic performance indicators of the steam turbine as a whole.

The specified technical result in the implementation of the invention is achieved by the fact that in the thrust bearing of the shaft of the turbomachine, comprising a bearing housing consisting of an upper and lower half-shells, upper and lower half-shells with supporting spherical surfaces made mutually conjugated with the inner bore half-shell of the bearing housing, work and installation pads, an inner annular channel made in the upper and lower half-liners, channels for supplying and removing lubricant to the workers and installation pads, oil seal assembly — the supporting spherical surfaces of the upper and lower supporting half-shells are installed with a gap between them of at least 0.003 of the sphere diameter by the half-shell of the bearing housing, while in the lower half-shell of the bearing housing a high-pressure lubricant is supplied with the possibility of an independent external source through the supply unit equipped with a check valve, and from an internal source, through two internal cross channels that are connected to pockets located on the spheres bearing surface of the lower half-shell of the bearing housing, and the main supply of lubricant to the supporting surface of the lower half-liner is made through channels made at an angle to the horizontal plane of the connector of the supporting half-liners corresponding to the angle of the tangent to the shaft in the direction of rotation and connected to the inner annular channel, and the supply of lubricant to the working and installation pads from the inner annular channel of the main supply of lubricant is carried out through a system of radial-axial channels made in the upper, and the lower half-shells, while cooling the working and installation pads, as well as the removal of spent lubricant from the interdisk space of the rotor shaft and the inter-journal space of the thrust bearing, is carried out by a system of radial and tangential channels made in the lower and upper half-shells, and the discharge of used lubricant of the supporting elements of the half-liners made through radial-end bevels made on both sides of the supporting spherical surface of the half-liners, as well as radial channels, nennyh on the working surface of the lower semiloose leaves a lubricant exit area of the carrier layer of the hydrodynamic wedge. At the same time, in the lower part of the oil seals of the thrust bearing, symmetrical grooves for directional discharge of the used lubricant are made and spring-loaded.

The analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information, did not reveal an analogue characterized by features identical or equivalent to the above. The definition from the list of identified analogues of the prototype as the closest device for the totality of features made it possible to determine the set of essential distinguishing features in relation to the technical result perceived by the applicant, as set forth in the following claims.

Therefore, the proposed device meets the criteria of patentability of the invention of "novelty."

To verify the conformity of the proposed technical solution with the patentability criterion of the invention "inventive step", the applicant conducted an additional search on the patent and scientific and technical information known from the prior art. The search results showed that the invention does not follow from the prior art and does not imply:

- addition of a known device by any known parts attached to it according to known rules, in order to achieve a technical result in respect of which the effect of such additions is established;

- replacement of any part of the known device with another part known from the corresponding prior art with a part to achieve a technical result in respect of which the effect of such a replacement is established;

- the exclusion of any part (element) of the device with the simultaneous exclusion due to its presence of a function and the achievement of the result known from the prior art for such an exception;

- an increase in the number of elements of the same type to enhance the technical result due to the presence in the device of precisely such elements;

- creation of a device consisting of known parts, the choice of which and the connection between them are based on known rules, recommendations, and the technical result achieved in this case is due only to the known properties of the parts of this tool and the connections between them.

Moreover, in order to achieve the task and, accordingly, to obtain the desired technical result, the applicant introduced structural and non-obvious, from the point of view of the technical task to be solved for the specialist, design changes into the support and thrust bearing of the specialist, and also provided him with new elements and connections.

In particular, the design of the support thrust plain bearing proposed by the invention allows to provide:

firstly, conditions to ensure uniform distribution of the temperature field of the level and increase the reliability of the work, installation blocks and working surfaces of the thrust bearing at nominal and increased specific loads due to the implementation of the reference mutually conjugate spherical surfaces with a guaranteed gap between them equal to not less than 0.003 diameter of the sphere half-shell of the bearing housing;

secondly, the optimal self-alignment of the liner relative to the shaft of the turbomachine due to the organization of an additional supply of high-pressure lubricant through the internal radial-axial channels to the bearing spherical bearing surfaces from both the internal and external sources. The use of movable, spring-loaded oil seals 34 additionally provides the possibility of optimal self-alignment of the liner and a decrease in the amount of lubricant leaks in cases of thermal misalignment or distortions of the supports of the steam turbine;

thirdly, the optimal organization of the supply and removal of lubricant, including due to the exclusion of the mixing process of the supplied and spent lubricant, the effective removal of which is ensured by radial end bevels 19 and channels 20, in the supporting part of the upper and lower half liners. This ensures that the temperature of the supplied lubricant is maintained unchanged from its nominal operating value;

fourthly, the organization of an individual (separate) supply of lubricant to the working 21 and installation 22 pads, their effective cooling due to the implementation of channels 23-27, 32, 33, as well as the organization of the directed removal of the used lubricant through a system of tangential and radial channels 29, 30 , 31.

Thus, we can conclude that the invention ensures the achievement of the technical result perceived by the applicant and meets the patentability criterion of the invention "inventive step".

In the drawings explaining the essence of the invention, are presented: FIG. 1, which shows a longitudinal section of a thrust plain bearing along the BB plane; figure 2, which shows a cross section of a thrust bearing in a plane AA; figure 3, which shows a cross section of a thrust bearing in the plane G-G; 4, which shows a view D of a fragment of a cross section of a thrust plain bearing along the G-D plane.

The thrust block bearing of the turbomachine shaft consists of the upper 1 and lower 2 half-bearings of the bearing housing with pressure pads 3, as well as the upper 4 and lower 5 half-shells with a supporting surface 6 made of antifriction alloy and containing hydrostatic pockets 7. In the lower half-shell 5 channel 8 and cross channels 9 directed to spherical bearing surfaces 10 of the lower half-hole 5, bearing housing including pockets 11. Channel 8 is connected to the high-pressure lubricant supply unit 12 from an external source ika provided with a check valve 13. The main inlet 14 is carried via lubricant outlet 15 in the pad 3, poluoboymy upper bearing housing and into the annular space 16 through channels 17 formed in the lower semiloose leaves. The channels 17 (figure 2) are located at an angle coinciding with the angle of the tangent to the shaft in the direction of rotation "w", and go to the eccentric bore 18, located on the supporting surface 6 of the lower half-liner, on the intersecting axes of the channels 17.

The proposed arrangement of a thrust plain bearing allows the additional removal of waste grease through radial end bevels 19, made symmetrically from 2 sides of the working surface of the upper and lower half liners, as well as radial channels 20. Moreover, the beginning of the end bevels of the lower half liner 5 and the axis coordinate the channels 20 are determined by the angle "β" to the horizontal plane of the liner against the direction of rotation of the shaft, in the area of the grease exit from the bearing hydrodynamics rotor shaft nomic wedge.

The supply of lubricant from the annular cavity 16 is made separately to the working 21 and installation 22 pads due to the implementation of the internal radial-axial channels 23, 24, 25, 26, 27, and the discharge of the used lubricant from the inter-disk as well as the inter-deck spaces 28 (Fig. 3) implemented through a system of channels 29, 30, 31, made radially and tangentially to the circumference of the liner, while the working and installation pads 21, 22 are equipped with channels 32, 33, designed to cool their working surfaces. From channels 32, 33, as well as from channels 29, 30, the grease is sequentially directed to the bearing housing and then to the drain manifold of the steam turbine lubrication system.

The self-alignment of the thrust bearing relative to the shaft in the axial direction during its rotation is ensured: firstly, by minimizing the gap between the mutually conjugated spherical surfaces of the half-shells 1, 2 of the bearing housing and half-liners 2, 4, equal to at least 0.003 of the sphere diameter to the half-shells of the bearing housing ; secondly, due to the design of the bearing, the possibility of supplying high-pressure grease 13 to pockets 7, 11 through internal channels 8, 9 from an external source in the start and stop modes of turbomachines, and in the nominal operation mode of a steam turbine by selecting high-pressure grease from developed a hydrodynamic wedge between the liner and the shaft (the so-called internal source) through the pockets 7, the inner cross channels 9 to the pockets 11 on the spherical bearing surface of the lower half-hollow 2; thirdly, due to the use of movable spring-loaded oil seals 34, not limiting the mobility of the liner in cases of possible misalignment of the shaft during misalignment of the supports of the turbomachine.

In the case of the lower halves of the oil seals 34, symmetrical grooves 35 are made (Fig. 1) for the directional discharge of the used lubricant from the inter-seal space 36 into the bearing housing and the drain manifold of the steam turbine lubrication system. Moreover, the bearing seals of the proposed device significantly reduce oil leakage from the bearing in cases of possible misalignment of the turbine unit shaft.

The support thrust bearing works as follows.

The lubricant flow 14, at a nominal pressure of 0.06-0.12 MPa, enters through the hole 15 and the annular cavity 16, the channels 17 and the eccentric bore 18 on the working surface 6 of the lower half-liner 4. With the beginning of rotation of the rotor shaft of the turbomachine and as it increases speed ("w") to the nominal value in the gap between the shaft and the working surface, a hydrodynamic wedge is formed, which causes the shaft to emerge by the required value. The optimal size of the area of formation of the hydrodynamic wedge, as well as the guaranteed ascent of the shaft to an important degree, is due to the preservation of strict parallelism of the supporting surfaces of the upper and lower half-liners and the size of their installation clearance to the rotor shaft of the steam turbine in the axial direction, equal to at least 0.003 of the sphere diameter to the half-shells of the bearing housing. The clearance less than the proposed value significantly reduces the bearing capacity of the bearing. In this case, the bearing capacity of the bearing is determined by the size of the ascent of the shaft, its location relative to the bore in the vertical and horizontal directions, the temperature distribution at various loads at all possible operating modes of the turbomachines.

Fresh lubricant coming from the channels 17 in a direction tangential to the shaft in the direction of its rotation gets into the eccentric bore 18 located on the intersecting axes with the channels 17, which prevents the irregular flow of the supplied lubricant into the upper half-liner and improves the conditions for the lubricant to enter the working surface of the lower half-liner 5.

Three pockets 7 are made from both ends of the working surface of the lower half-liner 5 for supplying high-pressure lubricant, located at an angle "γ", symmetrically to each other and relative to the vertical axis of the liner. In the same way, pockets 11 are made on the inner spherical surface of the lower half-hole 2. In this case, the pockets 7, 11 are connected by radial cross channels 9, and through the pockets 7 and channels 8 they are connected to the high-pressure lubricant supply unit 12 through the external lubricant supply unit equipped with a check valve 13.

Thus, at the nominal operating mode of the steam turbine as a result of the appearance of a hydrodynamic wedge during rotation of the rotor shaft, in its developed region, from the pockets 7 located at an angle “γ”, selection is constantly carried out through the internal cross channels 9, respectively, compensated by the supply to the pockets 11, high pressure grease (5-6 MPa) on the supporting spherical surface of the lower half-hollow 2 of the bearing housing. The latter allows to provide a significant improvement in the mobility of the lower half-liner relative to the rotor shaft and, accordingly, the parallel installation of working and installation blocks relative to the rotor disk.

When starting or stopping the turbomachine, the high-pressure grease 12 is supplied from an external source equipped with a check valve 13. In this case, the grease through the channel 8, made in the lower half-hollow of the bearing housing, through the radial holes enters the pockets 7 and at the same time is metered through the internal cross channels 9 to pockets 11 on the lower half-shell of the bearing housing.

The aforementioned and proposed by the invention, structural changes in the arrangement of a thrust bearing provide an almost instantaneous effect of the ascent of the shaft on the lubricating layer even at a minimum frequency of rotation. At the same time, if necessary, the proposed device allows you to ensure the rotation of the liner relative to the longitudinal axis of the shaft line by the possibility of simultaneous ascent and the liner itself within the minimum clearance between the spherical surfaces relative to the half-shells of the bearing housing, as well as its optimal self-installation due to the design of automatic lubrication of a higher pressure on the opposite side of mutually conjugated supporting spherical surfaces.

In cases of distortions of the supports of the turbomachine or thermal misalignment of the rotor shaft during the nominal operation at the ends of the working surface of the bearing elements of the bearing, the pressure in the lubricant layer and the gaps, respectively, significantly differ in absolute value.

The implementation of mutually conjugated supporting spherical surfaces of the liner and the casing of the bearing housing with a gap between them makes it possible to ensure its self-installation relative to the shaft in the longitudinal direction. The organization of the internal cross channels of the metered supply of high-pressure lubricant additionally improves the self-installation of the support and thrust elements of the liner relative to the rotor shaft due to the possibility of automatic receipt of higher-pressure lubricants on the opposite side of the spherical supporting surface of the lower half-liner. The latter allows us to ensure the instantly previously unattainable in the known constructions instantaneous turn in the right direction, thereby eliminating distortions both on the supporting working surface and along the installation and working blocks, which contributes to a significant increase in the reliability of its operation and prevents the possibility of low-frequency vibration.

In the lower half-insert 5, at the exit from the carrier layer of the hydrodynamic wedge, in the zone of angle β, a region of negative pressures forms. To reduce the grease leakage and its transfer to the upper half-liner 4, end bevels 19 and radial channels 20 are made in this area, through which part of the hot spent grease is discharged directly into the housing of the bearing housing. The remaining insignificant amount of hot, spent lubricant is transferred to the working surface of the upper half-liner 3 and then, due to the execution of the end bevels 19, it enters the inter-sealing space and through the grooves 33 in the lower half of the seal 34 and the lower half-liner 5 and is sent to the housing of the bearing housing.

Possibility of an individual supply of lubricant to the working 21 and installation 22 pads, ensuring their effective cooling due to the supply of lubricant through channels 23, 24, 25, 26, 27 and 32, 33, as well as directed lubrication through the system of channels 29-31, in combination with the possibility of automatic self-installation of all pads relative to the thrust disc of the shaft of the turbomachine, it provides a significant increase in the bearing capacity and reliability of the thrust bearing in all operating modes of the unit.

The inevitability of the practical occurrence of distortions of the supports and thermal misalignment of the shaft line, constantly occurring during the operation of turbomachines, causes the appearance of uneven specific loads at the ends of the working surface of the lower half-liners and the majority of installed work and installation pads. The latter leads to a sharp decrease in the bearing capacity of thrust bearings, their intensive wear and, as a result, an increase in the temperature and vibration level of their work. In this regard, the invention allows to provide a large reserve of bearing capacity and vibrational reliability of the bearing in all operating modes of turbine units.

Thus, the above information in the description and drawings indicate that the following set of conditions is met when using the proposed device of a thrust bearing:

- a tool that embodies the proposed technical solution in its implementation, is used in the production and operation of thrust plain bearings for steam turbine rotors and medium and high power turbogenerators;

- for the claimed device in the form described in the independent clause of the patent formula for the invention set forth below, the possibility of its implementation using the means and methods given in the description and drawings of the application is confirmed;

- a tool embodying the invention in its actual implementation, is able to achieve the achievement of the technical result perceived by the applicant and provides improved technical and economic performance of the steam turbine as a whole.

Therefore, the present invention meets the patentability criterion of "industrial applicability".

Claims (4)

1. The thrust bearing of the sliding shaft of the turbomachine, which includes a housing consisting of upper and lower half-shells, upper and lower supporting half-shells with supporting spherical surfaces, made mutually interfaced with the inner bore half-shell of the bearing housing, working and installation pads, inner annular channel, made in the upper and lower half liners, channels for supplying and discharging lubricant for working and installation pads, an oil seal assembly, characterized in that the upper and lower supporting half breathers with supporting spherical surfaces are installed with a gap between them, and in the lower half-cage of the bearing housing, high-pressure lubrication is made with the possibility of supplying from an independent external source through a supply unit containing a non-return valve, and from an internal source through two internal cross channels, connected to pockets that are made on a spherical bearing surface of the lower half-hollow of the bearing housing, while the main supply of lubricant to the bearing surface of the lower bearing the half-liner is made through channels located at an angle to the horizontal plane of the connector of the supporting half-liners and connected to the inner annular channel, and the supply of lubricant to the working and installation pads from the inner annular channel is made both in the upper and lower supporting half-liners through a system of radial-axial channels, moreover, the cooling of the working and installation pads, as well as the removal of the used grease from the interdisk space of the rotor and the inter-deck space of the thrust bearing, are carried out through a system of radial and tangential channels made in the lower and upper supporting half-shells, and the waste lubricant was removed from the supporting elements of the supporting half-shells through radial-end bevels made on both sides of the supporting surface of the supporting half-shells, as well as radial channels made on the supporting spherical surface of the lower supporting half-liner, in the area of lubricant exit from the bearing layer of the hydrodynamic wedge. 2. The thrust bearing according to claim 1, characterized in that the gap between the spherical bearing surfaces of the upper and lower supporting half-shells is at least 0.003 of the sphere diameter by the half-shell of the bearing housing. 3. The thrust bearing according to claim 1, characterized in that the angle of the channels of the main supply of lubricant to the supporting surface of the lower supporting half-liner corresponds to the angle of tangent to the shaft in the direction of rotation. 4. The thrust bearing according to any one of claims 1 to 3, characterized in that in the housing of the lower halves of the oil seals there are symmetrical grooves for directional discharge of the used lubricant, and the seals are spring loaded.

Images