JP2006183702A - Thrust bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate formation of a fluid film supporting slide lubrication of a taper land bearing, and to increase load capacity of a thrust bearing. <P>SOLUTION: A thrust pad bearing is the taper land bearing having the doughnut disc shape, having a plurality of grooves radially extending on its sliding surface opposite to a thrust collar, and further having a tilted plane on a part of the sliding surface between the grooves, and a horizontal face on a remaining part. A boundary line between the tilted plane and the horizontal face is tilted to the radial direction, and the tilting direction of the boundary line from an inner side to an outer side of the taper land bearing is opposite to the rotating direction of the thrust collar with respect to the radial direction. Further an angular portion formed between the groove of the thrust pad bearing and the tilted plane may be formed by two or more tilted faces larger than a tilt angle of the tilted plane, or formed by a curved face. Further a lower portion of the groove of the thrust pad bearing is formed by a curved face. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a technique for providing a fluid machine.

  Patent Document 1 discloses a mechanism of a fluid machine.

JP 2003-232339 A

  In the first place, a fluid machine converts fluid energy into mechanical energy, and conversely converts mechanical energy into fluid energy. The former represents a water wheel and the latter represents a pump. Due to this characteristic, there is a difference in fluid pressure between the inlet side and the outlet side of the fluid machine, so that an axial load based on the pressure difference is generated on the rotating body of the fluid machine, that is, the impeller, the main shaft, and the like. A thrust bearing is used to support the impeller and the main shaft against this axial load and maintain a smooth rotational state.

  Since a fluid machine has a large axial load and is forced to operate for a long time, a sliding bearing is used as a thrust bearing. The thrust bearing is composed of an impeller, a disc-shaped thrust collar that is attached to the main shaft, rotates with the impeller, and the main shaft, and a stationary thrust pad bearing that supports the thrust collar. The cross sectional shape of the thrust pad bearing is generally an inclined plane pad bearing shown in FIG. 5, a Rayleigh step bearing shown in FIG. 6, and a taper land bearing shown in FIG.

  Among these, the taper land bearing in which the sliding surface facing the thrust collar is formed by the inclined flat surface portion 1 and the horizontal surface portion 2 is used for the fluid machine. FIG. 8 shows the appearance of the taper land bearing as viewed from the sliding surface side. The overall shape is a donut-shaped disk shape, and there are a plurality of radially extending grooves 3 on the sliding surface facing the thrust collar. A part of the sliding surface between the grooves is an inclined plane 1 and the remaining part is a horizontal plane 2. A boundary line 21 between the inclined plane 1 and the horizontal plane 2 faces in the radial direction.

  In recent years, fluid machines are required to have a high rotational speed due to the need for miniaturization, and the axial load acting on the thrust bearing is increasing. Therefore, an attempt to increase the load capacity of the thrust bearing is made, and Patent Document 1 is known.

  An object of the present invention is to increase the load capacity of a thrust bearing. For this purpose, the fluid film 30 formed between the thrust collar 4 and the thrust pad bearing 5 supporting the sliding lubrication must be maintained. Therefore, the behavior of the fluid film 30 was studied. The fluid film 30 includes a boundary layer of the thrust collar 4 and a boundary layer of the thrust pad bearing 5. Since the thrust collar 4 rotates together with the impeller and the main shaft, the boundary layer of the thrust collar 4 also rotates. This velocity vector is Vt.

  Further, the boundary layer of the thrust collar 4 receives a centrifugal force due to the rotation, and a velocity vector Vr is generated. Therefore, it was found that the boundary layer of the thrust collar 4 flows with the velocity vector V outward from the tangential direction of the rotation axis.

  On the other hand, as shown in FIG. 8, the boundary line 21 between the inclined plane 1 and the horizontal plane 2 of the tapered land bearing is oriented in the radial direction, and therefore intersects the velocity vector V of the boundary layer of the thrust collar 4 at an acute angle. As a result, it has been found that the boundary layer of the thrust collar 4 leaks out toward the outer periphery and inhibits the formation of the fluid film 30. Therefore, it was found that the fluid film 30 is formed even when the load capacity increases by preventing the boundary layer of the thrust collar 4 from leaking out.

  Further, it has been found that when the tip 3a of the inclined plane portion is an edge, the flow of the fluid film 30 is disturbed and the formation of the fluid film 30 is inhibited. Therefore, it has been found that if the flow of the fluid film 30 at the leading edge 3a is made smooth, the fluid film 30 is formed even when the load capacity increases.

  The second object of the present invention is to prevent the fluid film 30 from being cut off due to the eccentric load of the axial load acting on the thrust bearing. Since the fluid machine has a wide operation range, when it is in an operation state greatly deviating from the design point, the fluid force acting on the casing and the impeller is unbalanced, and the axial load is offset. Since the eccentric load is larger than the design load capacity, the fluid film 30 formed between the thrust collar 4 and the taper land bearing 5 is cut. In this case, the thrust collar 4 and the taper land bearing 5 come into solid contact with each other, so that wear occurs. When the thrust collar 4 and the taper land bearing 5 are remarkable, seizure occurs. Therefore, this must be prevented.

  The third object of the present invention is to stably fix the taper land bearing for a long period of time. Fluid machines are machined and assembled with sufficient accuracy, but due to dimensional tolerances, rotating bodies such as impellers and main shafts are always unbalanced, and the entire fluid machine vibrates during operation. When the operation period is long, the screw for fixing the taper land bearing may be loosened due to vibration. When the taper land bearing becomes unstable, the load capacity decreases. If it is remarkable, the screw is removed, and the rotating thrust collar 4 is curled, forcing the operation to stop. Therefore, the taper land bearing 5 can be stably fixed for a long period of time if it is not based on a frictional force like a screw.

  A fourth object of the present invention is to improve the starting characteristics of a fluid machine. The fluid film 30 that supports the sliding lubrication of the thrust bearing is formed by being drawn into the thrust collar 4 that rotates together with the impeller and the main shaft due to the viscosity of the fluid.

  Therefore, the fluid film 30 is not formed when the impeller before starting and the main shaft are stopped. Since the axial load is generated at the same time as starting, the thrust bearing thrust collar 4 and the taper land bearing 5 are in solid contact at the moment of starting, so the static friction resistance increases depending on the material of the thrust collar 4 and the taper land bearing 5, It becomes difficult to start. Therefore, the static friction resistance of the thrust bearing at the time of starting must be reduced.

  For the first purpose, the present invention provides a thrust bearing comprising a thrust collar provided on a rotating body of a fluid machine and a thrust pad bearing that supports the thrust collar against an axial load acting on the thrust collar. The thrust pad bearing has a donut-shaped disk shape, and has a plurality of radially extending grooves on a sliding surface facing the thrust collar, and a part of the sliding surface between the grooves is A tapered land bearing having an inclined plane and the remaining portion being a horizontal plane, and a boundary line between the inclined plane and the horizontal plane is inclined with respect to a radial direction, and the boundary line extending from the inside to the outside of the tapered land bearing is The inclination direction is opposite to the rotation direction of the thrust collar with respect to the radial direction.

  Further, the corner portion formed by the groove and the inclined plane of the thrust pad bearing is formed by two or more inclined surfaces larger than the inclination angle of the inclined plane, or is formed by a curved surface. Furthermore, the lower part of the groove of the thrust pad bearing is formed as a curved surface.

  For a second object, the present invention provides a thrust bearing comprising a thrust collar provided on a rotating body of a fluid machine and a thrust pad bearing that supports the thrust collar against an axial load acting on the thrust collar. The thrust pad bearing has a donut-shaped disk shape, and the back side (the anti-sliding surface) of the sliding surface facing the thrust collar is supported by an elastic body, and the outer peripheral side of the thrust pad bearing is a ring. The ring-shaped elastic body has a circular cross section, and the outer peripheral side of the ring-shaped elastic body is supported by a cylindrical casing.

  For the third object, the present invention provides a thrust collar provided on a rotating body of a fluid machine having an intermediate casing and an outlet casing, and a thrust pad bearing that supports the thrust collar against an axial load acting on the thrust collar. The thrust pad bearing has a donut-shaped disk shape, and has a plurality of radially extending grooves on a sliding surface facing the thrust collar, and a comb shape that fits in the groove The thrust pad bearing retainer is supported by the intermediate casing with a cylindrical member through a ring-shaped elastic body.

  For a fourth object, the present invention provides a thrust bearing comprising a thrust collar provided on a rotating body of a fluid machine and a thrust pad bearing that supports the thrust collar against an axial load acting on the thrust collar. The thrust pad bearing has a donut-shaped disk shape, and the back side (the anti-sliding surface) of the sliding surface facing the thrust collar is supported by an elastic body. One thrust pad bearing is made of a material in which one of the thrust pad bearings has a smaller coefficient of static friction on the sliding surface facing the thrust collar than that of the other thrust pad bearing, The sliding surface of the thrust pad bearing made of a material having a small static friction coefficient protrudes in the direction of the thrust collar from the sliding surface of the other thrust pad bearing. An elastic body for supporting the anti-sliding surface of the thrust pad bearing of a small coefficient of a material is softer than the elastic body for supporting the anti-sliding surface of the other of the thrust pad bearings. The material of the thrust pad bearing having a small static friction coefficient is resin mainly composed of Teflon (registered trademark).

  The first effect is that formation of a fluid film that supports sliding lubrication of the thrust bearing is promoted, and the load capacity of the thrust bearing is increased. That is, when the boundary line between the inclined plane and the horizontal plane is inclined relative to the radial direction in the direction opposite to the rotational direction of the thrust collar, the inclination direction of the inclined plane of the tapered land bearing is the rotation axis at the boundary line. It faces outward from the tangential direction. This is the same as the flow direction of the fluid film that supports the sliding lubrication formed between the thrust collar and the taper land bearing.

  Therefore, since the flow of the fluid film faces the boundary line between the inclined plane and the horizontal plane, the fluid film does not leak to the outer peripheral side of the taper land bearing, and the formation of the fluid film is promoted. In addition, the tip edge of the inclined flat surface of the taper land bearing has an obtuse angle or a curved surface, so that the fluid film that supports sliding lubrication flows smoothly when passing the tip edge, and the formation of the fluid film is further promoted. .

  The second effect is that since the outer periphery of the taper land bearing is supported by an elastic body having a circular cross section, the taper land bearing has a degree of freedom in which it can easily move in the axial direction.

  Furthermore, since the anti-sliding surface of the taper land bearing is supported by the elastic body, the elastic body supporting the anti-sliding surface contracts against the eccentric load of the axial load to cancel the uneven load. As a result, the fluid film that supports the sliding lubrication of the thrust bearing does not break, and wear of the thrust bearing can be reduced.

  The third effect is that the taper land bearing is supported by the pressing pressure of the intermediate casing via the taper land bearing presser, the elastic body, and the cylindrical member. The taper land bearing can be stably supported for a long time.

  The fourth effect is that when the fluid machine is stopped, the taper land bearing in solid contact with the thrust collar has the smaller static friction coefficient, so that the frictional resistance of the thrust bearing at the time of start-up becomes small and it becomes easy to start.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a front view of a taper land bearing showing an embodiment of the present invention. The main body is a donut-shaped disk, and 12 grooves 3 extending in the radial direction are equally arranged in the circumferential direction. An inclined plane 1 having a width W1 from the groove 3 is provided. Since the inclined plane 1 is provided facing the groove 3, the boundary line 21 between the inclined plane 1 and the horizontal plane 2 is parallel to the groove 3.

  On the other hand, when the viewpoint is changed and viewed from the intersection of the boundary line 21 and the taper land bearing inner diameter, the boundary line 21 faces the radial direction as shown in FIG. 8 in the conventional taper land bearing. Tilt to the direction. That is, the inclined plane 1 is manufactured so that the inclined direction of the inclined plane 1 is more outward than the tangential direction of the rotation axis at the position of the boundary line 21. Accordingly, since the flow direction (vector V) of the fluid film 30 supporting the sliding lubrication is the same as the direction of the inclined plane 1 at the boundary line 21, the fluid film does not leak to the outer periphery, and the formation of the fluid film is promoted. The

  FIG. 2 is a cross-sectional view of the taper land bearing according to the present invention taken along the line AA. A corner formed by the inclined plane 1 and the groove 3 is formed by two inclined surfaces 1a and 1b having inclination angles αa and αb larger than the inclination angle α of the inclined plane 1. Therefore, since the radius of curvature of the streamline increases when the fluid passes through the inclined surfaces 1a and 1b, the speed change along the streamline also decreases, and the fluid easily flows into the inclined plane 1, thereby forming the fluid film 30. Promoted. Furthermore, since the lower part of the groove 3 is a curved surface, a vortex is generated along the groove 3. Since the pressure in the central portion of the vortex is smaller than that in the peripheral portion, the fluid can be easily drawn into the groove 3 from the outer peripheral side and the inner peripheral side of the tapered land bearing. As a result, the fluid easily flows into the inclined plane 1 and the formation of the fluid film 30 is promoted.

  FIG. 3 is a sectional view showing an embodiment of the present invention. A thrust collar 5 attached to the main shaft 6 is supported by a taper land bearing 4. The taper land bearing 4 is supported by a cylindrical casing 7 via a ring-shaped elastic body 10b having a circular cross section at the outer periphery. As a result, the taper land bearing 4 can move in the axial direction. Further, since the taper land bearing 4 is supported on the side opposite to the sliding surface by the elastic body 10a, the elastic body 10a contracts and cancels the uneven load even if an axial load is offset. The load can be kept below the load capacity.

  Further, a taper land bearing retainer 12 is provided so as to fit in the groove 3 of the taper land bearing 4. The taper land bearing retainer 12 is supported by the intermediate casing 8 via the elastic body 10 c and the cylindrical member 11. The taper land bearing holder 12 is fixed by the pressing pressure from the intermediate casing 8. Since the pressing pressure does not decrease even when a long-term vibration is applied, the taper land bearing 4 is stably supported through the taper land bearing retainer 12 for a long period of time.

  FIG. 4 is a sectional view showing an embodiment of the present invention. In this embodiment, the taper land bearing 4 is divided into two parts in the radial direction. The outer tapered land bearing 4b is made of a material having a static friction coefficient smaller than that of the inner tapered land bearing 4a. The elastic body 10b for positioning in the radial direction is installed on the outer tapered land bearing 4b. The elastic bodies 10a1 and 10a2 installed on the anti-sliding surface side of the taper land bearings 4a and 4b are installed in the respective taper land bearings 4a and 4b.

  The elastic body 10a2 is a softer material than the elastic body 10a1. Further, the anti-sliding surface side of the taper land bearing 4b is supported so that the distance between the horizontal surface 2 of the taper land bearing 4b and the thrust collar 5 is smaller than the distance between the horizontal surface 2 of the taper land bearing 4a and the thrust collar 5. The size of the elastic body 10a2 is determined. Further, the taper land bearing presser 12 is extended to the inner diameter side, and is configured to press the taper land bearings 4a and 4b simultaneously.

  Therefore, at the time of start-up, the thrust collar 5 is first supported by the outer tapered land bearing 4b having a small static friction coefficient and starts to rotate easily. When the rated operation is reached and the axial load becomes larger than that at the time of startup, the thrust collar 5 is supported by the taper land bearing 4a. That is, the elastic body 10a2 supporting the anti-sliding surface of the taper land bearing 4b having a small static friction coefficient is softer than the elastic body 10a1 supporting the anti-sliding surface of the inner taper land bearing 4a. Because it is small.

  In this embodiment, a resin mainly composed of Teflon (registered trademark) is used as the material of the taper land bearing 4b having a small static friction coefficient. In general, Teflon resin is soft and is likely to be worn when used in a thrust bearing. However, in the present invention, the inner taper land bearing 4a receives most of the axial load during rated operation. Does not wear.

  In the above description, the embodiments of the present invention have been described on the assumption that the hydraulic turbine and pump are hydraulic machines. However, the present invention is not particularly limited to these and can be used for all fluid machines having a thrust bearing.

The front view of the taper land bearing which shows the Example based on this invention Sectional drawing of the taper land bearing which shows the Example based on this invention Sectional drawing of the taper land bearing which shows the Example based on this invention Sectional drawing of the taper land bearing which shows the Example based on this invention Sectional view of inclined flat pad bearing showing the prior art Cross section of a Rayleigh step bearing showing the prior art Cross section of tapered land bearing showing conventional technology Front view of tapered land bearing showing conventional technology

Explanation of symbols

1 Tapered Land Bearing Inclined Plane 1a Tapered Land Bearing Inclined Plane 1b Tapered Land Bearing Inclined Plane 2 Tapered Land Bearing Horizontal Plane 3 Tapered Land Bearing Groove 4 Tapered Land Bearing 5 Thrust Collar 6 Spindle 7 Outlet Casing 8 Intermediate Casing 9 Seal 10a Elastic body 10a1 which supports the anti-sliding surface of the taper land bearing Elastic body 10a2 which supports the anti-sliding surface of the inner taper land bearing Elastic body 10b which supports the anti-sliding surface of the outer taper land bearing Elastic body 10c supporting the outer peripheral side of the elastic body 11 elastic body 11 supporting the taper land bearing retainer

Claims (8)

A thrust bearing comprising a thrust collar provided on a rotating body of a fluid machine and a thrust pad bearing that supports the thrust collar against an axial load acting on the thrust collar, wherein the thrust pad bearing is a donut-shaped disk The sliding surface facing the thrust collar has a plurality of radially extending grooves, and a part of the sliding surface between the grooves is an inclined plane, and the remaining portion is a horizontal plane. A taper land bearing, wherein a boundary line between the inclined plane and the horizontal plane is inclined with respect to a radial direction, and the inclination direction of the boundary line directed from the inside to the outside of the taper land bearing is a thrust collar of the radial direction. A thrust bearing characterized by being opposite to the rotational direction. 2. The thrust bearing according to claim 1, wherein a corner portion formed by the groove and the inclined plane of the thrust pad bearing is formed by two or more inclined surfaces which are larger than the inclined angle of the inclined plane. . The thrust bearing according to claim 1, wherein a corner portion formed by the groove and the inclined plane of the thrust pad bearing is formed by a curved surface. 2. The thrust bearing according to claim 1, wherein a lower portion of the groove of the thrust pad bearing is formed as a curved surface. A thrust bearing comprising a thrust collar provided on a rotating body of a fluid machine and a thrust pad bearing that supports the thrust collar against an axial load acting on the thrust collar, wherein the thrust pad bearing is a donut-shaped disk The back side (the anti-sliding surface) of the sliding surface facing the thrust collar is supported by an elastic body, and the outer peripheral side of the thrust pad bearing is supported by a ring-type elastic body. A thrust bearing support structure, wherein a cross section of the body is a circle, and an outer peripheral side of the ring-shaped elastic body is supported by a cylindrical casing. A thrust bearing comprising: a thrust collar provided on a rotating body of a fluid machine having an intermediate casing and an outlet casing; and a thrust pad bearing that supports the thrust collar against an axial load acting on the thrust collar. The bearing has a donut-shaped disc shape, a disc-shaped thrust pad having a plurality of radially extending grooves on a sliding surface facing the thrust collar and having comb-shaped projections inside the grooves. A thrust bearing comprising a bearing retainer, wherein the thrust pad bearing retainer is supported by an intermediate casing with a cylindrical member via a ring-shaped elastic body. A thrust bearing comprising a thrust collar provided on a rotating body of a fluid machine and a thrust pad bearing that supports the thrust collar against an axial load acting on the thrust collar, wherein the thrust pad bearing is a donut-shaped disk And the back side (the anti-sliding surface) of the sliding surface facing the thrust collar is supported by an elastic body, and the thrust pad bearing is composed of two thrust pad bearings in the radial direction, One of the thrust pad bearings is a material in which the static friction coefficient of the sliding surface facing the thrust collar is smaller than the static friction coefficient of the sliding surface of the other thrust pad bearing, and the thrust pad bearing is made of a material having a small static friction coefficient. The sliding surface protrudes in the direction of the thrust collar from the sliding surface of other thrust pad bearings, and the thrust is made of a material having a small static friction coefficient. Elastic body, a thrust bearing is softer characteristic than the elastic body for supporting the anti-sliding surface of the other of the thrust pad bearings supporting the anti-sliding surface of the head bearing. The thrust bearing according to claim 7, wherein the material of the thrust pad bearing having a small coefficient of static friction is a resin mainly composed of Teflon.

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