RU2630271C1 - Gasostastic bearing - Google Patents

Abstract

FIELD: machine engineering.

SUBSTANCE: gasostatic bearing contains a ring-shaped body (1) having at least one block (3), on which support surface there are two grooves, which are able to be connected through the throttling holes in the block (3) with the lubrication system in the bearing lubrication gap formed by the shaft and the support surface of the block (3), one of the grooves (10) is straight and located on the leading edge side of the block support surface (3), and the second one (11) is located on the upstream side of the support block (3) and has a crescent or arcuate shape. An annular groove is formed on the inner generating body surface (1), and on the block (3) there is a pin with a hole. Mounting of the block (3) on the body (1) is carried out by means of a pin (6) inserted into the bushings (5), installed in the body holes (1) made in the annular groove area and passing through the pin hole (4), located with gap in the body groove (1). In this case, an annular protrusion of spherical shape is provided on the pin (6), which is located with a gap in the pin hole.

EFFECT: increase the load bearing capacity with minimum lubricant consumption.

6 cl, 5 dwg

Description

The invention relates to machine parts, and in particular to designs of radial and thrust gas-static bearings intended for use, in particular, in high-speed rotor systems, for example, compressors, turbines, electric generators.

Known (see patent US 3318557) segmental gas-static bearing, made in the form of a bearing surface, on which grooves are applied, forming a circuit for supplying lubricating gas to the bearing clearance. According to the invention, the grooves can be either single, straight, or forming a certain contour. In particular, H-shaped grooves and grooves forming a closed rectangular contour with a central jumper into which gas is supplied through one throttle are described. This bearing refers to the so-called bearings with a contour supply of lubricant, in which lubrication is introduced into the working clearance of the bearing through a system of grooves on the surface of the blocks forming a closed circuit. The main disadvantage of these bearings is the increased lubricant consumption due to lubricant leaks through grooves located in the areas of the bearing with reduced pressure.

Known gas-static bearing (see patent US 6164827), made in the form of a bearing surface, on which there are grooves that form a gas supply circuit in the lubricating clearance of the bearing. In the invention, the dependences of the total volume of the grooves are determined, and their shapes are assigned, providing, if possible, the most complete gas supply to the lubricating gap. Patented are the shapes of grooves with a single gas supply choke, forming an x-shaped structure, an x-shaped structure with branches, as well as forms with several chokes, forming a regular symmetrical pattern of relatively short branched grooves. In the design of this bearing, the dependences of the total volumes of the grooves and their shapes are implemented, which provide the most complete gas supply to the lubricating layer. The disadvantage of such solutions, using both static and dynamic principles of operation, is the reduction of bearing capacity and stiffness due to leakage of lubricant from high pressure zones through the supply grooves (reverse lubrication).

A gas-static bearing is known (see RF patent for utility model No. 134602, class F16C 17/03, 2013), comprising pads spanning the shaft mounted pivotally in the housing with the possibility of rotation about an axis that is parallel to the shaft axis.

The bearing surfaces of the pads and the outer surface of the shaft form a lubricating gap. The feed channels are made in the pads for supplying a working medium to the lubricating gap. Each of the supply channels is connected to the corresponding channel of the inkjet control unit with which each block is equipped.

Each inkjet control unit for supplying a working medium is made in two stages. Its first stage is an element of the "nozzle-flapper" type. The executive body of the element "nozzle-flapper" is a metal membrane installed at the nozzle. The second stage contains a logical pneumatic jet element, which is connected by channels to a feedback loop, to a supply loop, a drain loop, with a control nozzle and a membrane channel. When the membrane contacts the nozzle, the supply of the working medium to the supply channel and, accordingly, the channels of the pads is blocked.

The disadvantage of this control scheme is the limitation on the speed of rotation of the shaft and the frequency of disturbances in the position of the shaft. The ability of the pads to rotate at a certain angle and shift in the radial direction due to damping devices to a certain extent allows damping shock overloads. The disadvantage is that the design of the pads is optimized to work with maintaining a constant clearance in the lubricating layer and the angle of rotation of the segment is zero in average over time, which does not allow using the gas-dynamic effect to ensure bearing capacity.

The closest analogue of the present invention is a gas-static bearing (see RF patent for utility model No. 154405, class F16C 17/03, 2014), comprising a housing in which pads with supply cavities are pivotally mounted, covering the shaft and forming their bearing surfaces with the outer surface of the shaft mounted in the bearing, lubricating clearance. Two grooves are made on the supporting surface of each block, one of which has a rectilinear shape, and the second a crescent or arcuate shape. In this case, the second groove in shape repeats the shape of pressure isolines distributed over the support surface of the shoe and is located along them. The grooves are in communication with the supply channels made in the block, through which compressed air is supplied to the grooves, which then enters the lubricating gap.

In the process of operation of the bearing unit with a rotating shaft, compressed air is supplied into the feeding cavities of the blocks, from where it enters the grooves in the grooves made on the bearing surfaces of the blocks and then into the lubricating gap. The compressed air in the lubrication gap prevents the shaft and shoe surfaces from touching. In the absence of an external load on the bearing, the pads are concentric with the shaft axis. Under the action of external force, the shaft is shifted in the housing in the radial direction. As a result, the average lubricating clearances between the surfaces of the shaft and the pads become different. In the area of the block where there is a minimum clearance, the greatest air pressure forces arise. On the contrary, in the place of the greatest clearance, the smallest forces arise. As a result of the vector addition of forces from all the pads, a total bearing reaction occurs that compensates for the external load. Pads transfer the load to the body through hinges. Due to the hinges, the pads are rotated around the center of the hinge under the action of aerodynamic forces and rotated to the equilibrium position, at which the torque on the pads becomes zero. In the equilibrium position, air enters the lubricating gap only through a straight groove, which ensures a maximum air distribution area with excess pressure in the lubricating gap. Since the pressure in the groove in the equilibrium position is equal to the pressure in the common supply cavity, air does not flow through the channel. The preservation of the same pressure along the entire length of the curved groove is provided by its curved shape, since the groove is located along the pressure contour in the lubricating gap, and the pressure on the contour is constant. Thus, the design of the bearing ensures its reliable operation in the entire range of modes and loads due to the automatic alignment of the shaft and the bearing surfaces of the pads.

The disadvantage of the described design is that it allows you to change the angle of rotation of the segment only under load and only at a given speed of rotation of the shaft. As a result, constant use of the gas-dynamic effect is impossible, since the angle of rotation of the block is not controlled and depends mainly on the pressure of the compressed gas supply to the lubricating gap and the load on the bearing block. The foregoing reduces bearing capacity and increases lubricant consumption.

The technical result of the present invention is to increase the bearing capacity with a minimum lubricant consumption due to the combination of gas-dynamic (due to the rotation of the blocks) and gas-static (due to the gas supply to the lubricating gap under excessive pressure) effects of load-bearing capacity, as well as due to the shape and location of grooves on the support pad surface.

The specified technical result is ensured by the fact that in the gas-static bearing, comprising a housing made in the form of a ring, at least one block, on the supporting surface of which there are two grooves that can be connected through throttle holes made in the block with the lubricant supply system to the bearing lubricating clearance, formed by the shaft and the bearing surface of the block, one of the grooves is straight and located on the input edge side of the bearing surface of the block, and the second is located on the sides s of the outlet edge of the support surface of the shoe and has a crescent or arc-shaped shape, it is new that an annular groove is made on the inner forming surface of the body, and there is a pin with a hole on the shoe, while the shoe is mounted on the body by means of a finger inserted into the bushings installed in the holes of the housing, made in the region of the annular groove, and passing through the hole of the trunnion, placed with a gap in the annular groove of the housing, while on the finger there is an annular protrusion having spheres eskuyu shape, which is located with clearance in a stud hole, wherein the bushing and the pin may be made of an elastic material on the outer surface of the pads can be formed flange. The distance from the input edge of the shoe support surface to the grooves located on its side is from 5 to 30% of the circumferential length of the shoe support surface, and the distance from the grooves to the lateral edges of the shoe support surface is from 10 to 40% of the axial length of the shoe support surface.

The essence of the claimed invention is illustrated by graphic materials on which:

- in FIG. 1 - gas-static bearing, general view, axonometric projection;

- in FIG. 2 - gas-static bearing and its block in the undeveloped state;

- in FIG. 3 - bearing block, view from the side of its bearing surface;

- in FIG. 4 - scan of the bearing surface of the bearing block;

- in FIG. 5 - a variety of bearing pads, view from the side of its bearing surface.

The gas-static bearing consists of a housing having mainly a ring shape, on the inner generatrix of which an annular groove 2 is made.

The bearing is equipped with pads 3. The number of pads may vary. So in FIG. Figure 1 shows the design of a radial bearing with three pads, but this does not mean that their number cannot be different, but not less than one.

The block (each block, if there are several) is equipped with a trunnion 4, which, when mounting the block, is placed in the annular groove 2 of the housing 1. For mounting in the trunnion, a through precision hole is made (not indicated by)

The dimensions along the width of the trunnion and the annular groove are correlated in such a way that when the trunnion is placed in the annular groove, structural axial clearances are maintained between the end surfaces of the trunnion 4 of the block 3 and the walls of the annular groove 2, allowing the block

make a rotation movement in the groove within certain limits (self-install).

For mounting the pads 3 in the housing 1, two holes located on the same axis are provided in the annular groove area (not indicated by the position). Sleeves are installed in the openings of the housing 5. A pin 6 is pressed into the sleeves 5 when installing the pads, which is passed through the precision hole of the shoe pin mentioned above. The bushings 5 are most expediently made of an elastic material, for example, spring steel, for example, 65G, 60C2A.

In the central part of the finger 6 there is an annular protrusion 7 of a spherical shape. In the assembled position of the block, this protrusion is located approximately in the central part of the precision hole of the pin. A bearing block is supported on this annular protrusion 7 of the finger 6 and has the ability to rotate relative to this annular protrusion to enable self-installation of the working (supporting) surface of the block relative to the shaft surface. Finger 6 is most expediently made of an elastic material, for example, spring steel, for example, 65G, 60S2A.

Thus, a block mounted in the housing (each block, if there are several of them) in a non-working position occupies a strictly defined position, and when the bearing is operating due to arising moments, it can freely rotate on the finger 6 around the center of the spherical surface of the annular protrusion 7 of the finger 6, ensuring self-installation of the shoe within the lubricating clearance of the bearing. Lubricating clearance is the most important characteristic of the bearing - it is the radial clearance between the shaft and the bearing surface of the block (s) of the bearing.

During the operation of the bearing, when the shaft rotates, the pads have the ability to turn on the fingers within the gap, forming tapering wedge-shaped gaps. This is due to the fact that the bushings 5 and the fingers 6 can elastically deform within the design gaps, thereby forming a pliable system. The dimensions and cross-sectional shape of the bushings and fingers can vary within wide limits to ensure the design elasticity of the bearings.

Block 3 (or pads 3, if there are several), to reduce their inertial characteristics, which is especially important for high-speed nodes, have a small thickness, however, to ensure the required circumferential stiffness, they can be equipped on the outer surface with flanges, the number of which can be different. So, the graphic materials show pads with flanges 8, 9, which does not mean that their number cannot be different.

In pin 4 there are collector holes (positions are not indicated), communicating with small cross-section channels (chokes) with grooves 10 and 11 on the supporting surface of the block (each block). In the collector holes introduced tubes 14 and 15 of the lubricant supply connected to the fittings 16 of the lubricant supply. On the opposite side, the collector holes of the pads are closed with plugs 17, attached to the housing with the help of strips 18.

Let us consider in more detail the implementation of the supporting surface of the shoe 3. The supporting surface of the shoe is shown in FIG. 3 and FIG. 4 and indicated by 19. The inlet edge of the abutment surface is indicated by “a”, the side by “b”, and the outlet by “c”.

The grooves 10 and 11 made on the supporting surface are intended for distribution of the lubricant entering the grooves through the holes 20 and 21 in the lubricating gap between the supporting surface of the bearing block and the shaft.

The groove 10 of the pads is made rectilinear, located on the side of the input edge "a" and is oriented parallel to the input edge.

The groove 11 of the pads is located on the side of the output edge "in" and has a crescent or arcuate shape.

The cross-sectional profile of the grooves 10 and 11 is not of fundamental importance and is determined by the technological capabilities in the manufacture of blocks. The only requirement is to ensure the volume of the grooves from the condition of preventing unstable oscillations of the "pneumatic hammer" type.

Consider in more detail the location of the grooves on the supporting surface of the pads.

The groove 10 of the pads is most appropriate to perform at a certain distance from its input edge "a". If it is placed too close to the input edge, then when the bearing is running, the lubricant consumption increases, associated with leaks in the direction opposite to the rotation of the shaft. The same thing happens if the ends of the grooves are too close to the side edges "b". At the same time, the execution of the groove 10 is too far from the input edge of the working surface of the block leads to a decrease in bearing capacity. As studies have shown, for the normal operation of the bearing, the optimal distance of the groove 10 from the input edge should be in the range from 5 to 30% of its circumferential length - l. The distance of the ends of the grooves 10 and 11 from the lateral edges should be within 10-40% of the axial length - b.

The groove 10 of the block (each block) is designed to supply lubricant to the working clearance in all operating modes of the bearing. The supply of lubricant through the groove 11 increases the pressure at the inlet of the groove, which leads to a proportional increase in the total pressure in the loaded block, i.e. the supply of lubricant through the groove 10 serves to additionally fill the dynamic diagram of the lubricating layer.

The supply of lubricant through the groove 11 provides a hydrostatic component of the bearing capacity.

In the General case, the lubricant in the groove 11 can be supplied at all operating modes of the bearing. However, to reduce lubricant consumption, the supply of lubricant to the groove 11 may be turned off, for example, when the shaft rotation speed is sufficient to form a sufficient gas-dynamic lubricant layer.

To improve the characteristics of the bearing and expand the nominal range of shaft rotation speed and shaft load on the supporting surface of the block (each block), an additional groove 23 can be made (Fig. 5).

The presence on the supporting surface of the three grooves provides a smoother adjustment of the bearing in terms of rotation speed and shaft load over a wider range.

During the operation of the bearing, grease can be supplied to these grooves along independent lines at various pressures.

The gas-static bearing operates as follows.

In the absence of rotation of the shaft and the supply of lubricant, the shaft rests on the supporting surface 19 of the block 3. At the same time, there is a significant moment of friction, and for the promotion of the shaft requires increased power. For heavy rotor systems with a specific block load of more than 0.02 MPa, starting and stopping in dry friction is practically impossible. When gas is supplied to the bearing through the lubricant (gas) supply pipes from an external source (not shown), excessive pressure arises in the lubricating gap. This occurs due to the spreading of gas through the grooves 10 and 11 in the lubricating clearance of the bearing. When a lubricant pressure of a certain value is reached, the shaft is completely detached from the support surface of the block due to the hydrostatic action of the overpressure field in the gap. In this case, the friction moment decreases sharply and is determined by the viscosity of the lubricant. From this moment, the shaft can be spun up to the rated speed

cars. In the process of accelerating the shaft, with increasing peripheral speed, there is a viscous involvement of the lubricant in the lubricating gap. The pads under the action of pressure forces in the lubricating layer are deployed in hinges formed by precision holes in the pins 4 of the pads 3 and the spherical surfaces of the protrusions 7 of the fingers 6. The spherical hinges, in addition, provide the possibility of the rotor system working under conditions of permissible deviations from the alignment of the bearings. During acceleration of the rotor, the pressure plot is transformed and takes on a form approximately corresponding to that shown in FIG. 4. The pressure contours in FIG. 4 are indicated by 22. In this case, the contribution of the dynamic component of the load-carrying capacity increases and can several times exceed the value of the initial static load-carrying capacity. In addition, the continuous supply of gas into the lubricating gap contributes to an increase in dynamic load capacity due to an increase in the initial pressure and density of the medium compared to a non-pressurized bearing.

The processes of promotion, operation and shutdown of the shaft, as a rule, are accompanied by the passage of the rotor system through the critical rotational speeds. In this case, significant loads can occur in the bearings. To reduce the loads associated with the dynamics of the shaft in the bearing, it is possible to install blocks using elastic elements formed by bushings 5 and fingers 6. Bushings 5 and fingers 6 can be deformed, allowing the blocks to move within structural clearances, damping vibrations.

The damping of the entire system also occurs due to friction between the ends of the pins of the pads 3 and the walls of the groove 2 of the housing 1.

The design of the claimed gas-static bearing combines in its operation both the principles of creating lifting force (gas-static and gas-dynamic) and provides the greatest load capacity at the lowest possible flow rate of the working fluid. The present invention provides the most efficient use of the potential of the lubricant source by optimizing the circuit for supplying it to the lubricating clearance of the bearing, as well as using the wedge effect by rotating the blocks by a given angle.

Claims (6)

1. The gas-static bearing, comprising a housing made in the form of a ring, at least one block, on the supporting surface of which there are two grooves that can be connected through throttle holes made in the block with a lubricant supply system into the bearing lubrication gap formed by the shaft and the bearing surface of the block , one of the grooves is made rectilinear and is located on the input edge side of the shoe support surface, and the second is located on the output edge of the shoe support surface and has a gray ovoid or arcuate shape, characterized in that an annular groove is made on the inner forming surface of the housing, and there is a pin with a hole on the shoe, while mounting the shoe on the housing is carried out by means of a finger inserted into bushings installed in the housing holes made in the region of the annular groove , and passing through the hole of the trunnion, placed with a gap in the annular groove of the housing, while on the finger made an annular protrusion having a spherical shape, which is located with a gap in the hole of the trunnions s. 2. The gas-static bearing, according to claim 1, characterized in that the bushings are made of elastic material. 3. The gas-static bearing, according to claim 1, characterized in that the finger is made of an elastic material. 4. The gas-static bearing according to claim 1, characterized in that flanges are made on the outer surface of the block. 5. The gas-static bearing according to claim 1, characterized in that the distance from the input edge of the support surface of the shoe to the groove located on its side is from 5 to 30% of the circumferential length of the support surface of the shoe. 6. The gas-static bearing according to claim 1, characterized in that the distance from the grooves to the lateral edges of the support surface of the shoe is from 10 to 40% of the axial length of the support surface of the shoe.

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