JP2009275860A - Revolving bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a revolving bearing in the form of a four point contact ball bearing embodied in a constitution using a retainer, reducing the axial direction dimension and sustaining a large rated load. <P>SOLUTION: A plurality of balls 3 held by the retainer 4 are interposed between groove-shaped raceway surfaces 1a, 1b, 2a, 2b of an inner ring 1 and an outer ring 2. The balls 3 make four point contact, in contacting with two curved surfaces 1aa, 1ab, 1ba, 1bb, 2aa, 2ab, 2ba, 2bb which constitute the raceway surfaces 1a, 1b, 2a, 2b of the inner 1 and outer rings 2. The retainer 4 assumes a band form curved in an arcuate shape along the raceway surfaces 1a, 1b, 2a, 2b, and pockets 4a to hold the balls 3 are formed in line in the circumferential direction. The shape of the inside surface of each pocket 4a is such as to contact with the ball 3 at a plurality of points P1 and P2 for each side of the inside surface in the retainer circumferential direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a large-size or super-large-size slewing bearing used for a slewing portion of, for example, a wind turbine for wind power generation.

  5 and 6 show an example of a wind turbine for wind power generation. The windmill 11 is provided with a nacelle 13 on a support base 12 so as to be able to turn horizontally, and a main shaft 15 is rotatably supported in a casing 14 of the nacelle 13. A blade 16 which is a wing is attached. The other end of the main shaft 15 is connected to the speed increaser 17, and the output shaft 18 of the speed increaser 17 is coupled to the rotor shaft of the generator 19.

  Wind turbines for wind power generation are very large, and the length of one blade 16 is several tens of meters, and some of them exceed 100 meters. Therefore, when the blade 16 rotates about the main shaft 15, the wind speed of the wind received by the blade 16 differs depending on the rotation position, for example, the position above the main shaft 15 and the position below the main shaft 15. While the blade 16 rotates, the angle of each blade 16 toward the wind is adjusted according to the wind speed so that each blade 16 receives the same load even if the wind speed is different. Further, the direction of the nacelle 13 is changed according to the change of the wind direction so that each blade 16 receives wind from the front (yaw). If the wind speed is too high and a large load may be received, the direction of the nacelle 13 may be reversed to allow the wind to escape.

As described above, in the wind turbine for wind power generation, it is necessary to change the angle of the blade 16 and the direction of the nacelle 13 according to the state of the wind, so that the blade 16 and the nacelle 13 can be swung by the swivel bearings 21 and 22, respectively. It is supported and turned by driving means (not shown). The characteristics of the slewing bearing for the windmill include that the dimensions are very large, the swing angle of the slewing is relatively small, and that it receives a variable load.
Regarding the dimensions, the outer ring outer diameter is 1000 to 3000 mm for blades and 1500 to 3500 mm for yaw. The swing angle is about 90 ° at the maximum for blades and 360 ° at the maximum for yaw. As for the fluctuating load, both the blade and the yaw are subjected to a fluctuating load, but the blade is often subjected to a sudden fluctuating load.

In a wide range of fields such as construction machines and machine tools, four-point contact ball bearings are used as slewing bearings (for example, Patent Documents 1 and 2). The four-point contact ball bearing is formed by forming each raceway surface of the inner ring and the outer ring with two curved surfaces, and interposing a plurality of balls so as to roll freely between these raceway surfaces. A large load capacity can be obtained with a simple configuration because the inner and outer rings are firmly clamped between the raceway surfaces and the rigidity of the inner and outer rings is high.
JP 2002-339981 A JP 2003-13963 A

  Therefore, we decided to adopt a four-point contact ball bearing for the slewing bearing for wind turbines. In adopting the four-point contact ball bearing, the ball holding method was considered as follows. That is, the slewing bearing for the windmill frequently oscillates within a relatively narrow turning range due to the fluctuating load as described above, and thus fretting is likely to occur. In order to prevent fretting, it is necessary to reduce the slip between the ball and the race by making the internal clearance negative. On the other hand, the contact angle of each ball changes at the time of swinging, and the revolving speed of the ball changes, thereby causing a ball advance / delay. However, the influence of the advance / delay becomes large due to the negative clearance and the load area widening. In order to prevent the balls from being scattered by this advance and delay, and to keep the balls at regular intervals, it was concluded that it is desirable to hold the balls with a cage rather than a spacer.

  When a cage is used, the following points are problems in a large or super large slewing bearing for a wind turbine. According to JIS B 0104-1991, a large bearing is defined as having an outer ring outer diameter of 180 to 800 mm.

  The first problem is the reduction in axial dimension. Since the slewing bearing for wind turbines has a very large radial dimension, the conventional one is heavy. In order to improve performance and reduce costs, it is required to shorten the axial dimension as much as possible to make the whole compact and lightweight. However, if the axial width w of the cage 4 is narrowed as shown in FIG. 7 in order to shorten the axial dimension of the bearing, the dimension a from the axial end to the pocket 4a becomes narrow, and the strength of the cage 4 is reduced. It becomes lower and cannot withstand the load caused by the delay of the advance of the ball.

  The second problem is securing a rated load of a predetermined size. Since the slewing bearing for a windmill receives a very large load at the maximum wind speed, a large load rating is required. To that end, it is conceivable to increase the number of balls by narrowing the pitch p between balls as shown in FIG. 7, but if the pitch p between balls is narrowed, the minimum width (circumferential dimension) of the pillar portion 4b of the cage 4 is considered. B) becomes narrower, the strength of the cage 4 is lowered, and it becomes impossible to withstand the load due to the advance and delay of the ball.

  The present invention has been made under the above-mentioned background, and its purpose is to provide a four-point contact ball bearing with a bearing structure, a compact size in the axial direction, and a swivel that provides a large rated load. It is to provide a bearing.

  In the slewing bearing according to the present invention, a plurality of balls held by a cage are interposed between the groove-shaped raceway surfaces of the inner ring and the outer ring, and the raceway surfaces of the inner ring and the outer ring are respectively located on both sides of the groove bottom. In a slewing bearing formed of two curved surfaces and in contact with each curved surface of the raceway surface of the inner and outer rings and contacting at four points, the cage is a belt-shaped band curved along each raceway surface. The pockets for holding the balls are formed side by side in the circumferential direction, and the shape of the inner peripheral surface of each pocket is set at a plurality of points on one side of the inner peripheral surface in the cage circumferential direction. It is characterized by having a shape in contact with.

According to the slewing bearing of this configuration, since the bearing type is a four-point contact ball bearing, the rated load is large while the configuration is simple compared to other types of bearings. Since the balls are securely held by the cage, the balls are not scattered due to the advance and delay of the balls, and the balls can always be held at equal intervals.
In addition, the shape of the inner peripheral surface of each pocket of the cage is such that the ball comes into contact with the ball at a plurality of points on one side in the circumferential direction on the inner peripheral surface, thereby adding to the cage by contact with the ball. The force can be dispersed to reduce the stress at the ball contact portion of the cage. Therefore, even if the dimension from the axial end of the cage to the pocket is narrowed and the width of the pillar portion of the cage is narrowed, it can withstand the force applied to the cage due to the advance and delay of the ball. As a result, the axial width of the cage can be reduced to reduce the axial dimension of the bearing, and the rated load can be further increased by reducing the pitch between the balls and increasing the number of balls.
Furthermore, when the inner peripheral surface of the pocket comes into contact with the ball at a plurality of points on one side in the circumferential direction, the area where the ball and the cage are close to each other is widened, and a large amount of lubricating oil is held at this close location. Therefore, the lubricity of the bearing is good.

In this invention, the shape of the cross-section along the cage axial direction of the pillar portion that is the portion between the pockets in the cage is a linear shape on both sides, and a bulging portion that bulges on the outer diameter side or inner diameter side in the middle portion. It can be made into the shape which has. The cross-sectional shape of the bulge portion along the cage axial direction is, for example, a V shape.
By providing a bulging portion at the axially intermediate portion of the pillar portion of the cage, the inner peripheral surface of each pocket can be brought into contact with the ball at a plurality of points on one circumferential side of the inner peripheral surface. If the cross-sectional shape of the bulging portion along the cage axial direction is V-shaped, the cage can be made relatively simple and easy to process.

In the present invention, the cage is made of a steel plate.
A steel plate is suitable for the material of the cage because it has high strength and is easy to process.

In this invention, the raceway surface where the said ball interposes may be provided in multiple rows.
When the raceway surface and the balls are provided in a double row, the static load rating can be increased by n times when the number of the ball rows is n, as compared to a single row. When the balls are in a double row, the axial width of the cage is widened, but it is not n times that in the case of a single row. Therefore, the rated load can be increased without increasing the axial width of the cage.

  Since the slewing bearing of the present invention can obtain the above-described effects, the wind turbine blade is supported so as to be pivotable about the axis substantially perpendicular to the main shaft axis with respect to the main shaft, and the wind turbine nacelle is supported. It can be suitably used for pivotally supporting the table.

  In the slewing bearing according to the present invention, a plurality of balls held by a cage are interposed between the groove-shaped raceway surfaces of the inner ring and the outer ring, and the raceway surfaces of the inner ring and the outer ring are respectively positioned on both sides of the groove bottom. In a slewing bearing formed of two curved surfaces and in which the balls are in contact with the curved surfaces of the inner and outer races at four points and are in contact with each other at four points, the cage has a belt shape curved in an arc along each of the raceway surfaces. Pockets for holding the respective balls are formed side by side in the circumferential direction, and the shape of the inner peripheral surface of each pocket is set at a plurality of points on one side of the inner peripheral surface in the circumferential direction of the cage. Due to the contact shape, the axial dimension becomes compact and a large load rating can be obtained.

  An embodiment of the present invention will be described with reference to FIGS. This slewing bearing is, for example, a bearing that supports the blade of a wind turbine for wind power generation so that it can pivot about an axis substantially perpendicular to the main shaft axis or a nacelle of the wind turbine relative to a support base. Used as a bearing to support.

  In FIG. 1, the slewing bearing includes an inner ring 1, an outer ring 2, and a plurality of balls 3 that are interposed between the inner and outer rings 1, 2, and the double-row raceway surfaces 1 a, 1 b, 2 a, 2 b, respectively. And a holder 4 for holding each row of balls 3 separately. Each of the raceway surfaces 1a, 1b, 2a, 2b of the inner and outer rings 1, 2 is composed of two curved surfaces 1aa, 1ab, 1ba, 1bb, 2aa, 2ab, 2ba, 2bb. Each of these two curved surfaces has a circular arc shape with a radius of curvature larger than that of the ball 3 and different centers of curvature. Between a pair of curved surfaces constituting each track surface 1a, 1b, 2a, 2b, groove portions 1ac, 1bc, 2ac, 2bc are formed. Each ball 3 comes into contact with the curved surfaces of the inner ring raceway surfaces 1a and 1b and the outer ring raceway surfaces 2a and 2b at four points. That is, this slewing bearing is configured as a four-point contact double row ball bearing. The inner ring 1 and the outer ring 2 are provided with mounting bolt holes 5 and 6, respectively. Grease is filled in the bearing space between the inner and outer rings 1 and 2, and both ends in the axial direction of the bearing space are sealed with seal members 7.

  As shown in FIGS. 2 to 4, the cages 4 in each row are in the shape of a belt curved in an arc along each track surface 1a, 1b, 2a, 2b, and the pockets 4a into which the balls 3 are fitted have a circumferential direction. Are formed side by side. The shape of the column part 4b which is a part between the pockets 4a (FIG. 4) is a bulging part 4bb in which both side parts 4ba are linear and the middle part swells in a V shape on the outer diameter side. Thus, by making the intermediate part of the column part 4b into the V-shaped swelling part 4bb, the inner peripheral surface of the pocket 4a contacts the ball 3 at two points P1 and P2 on one side in the circumferential direction. When the bulging portion 4bb is V-shaped, the cage 4 can be made relatively simple and easy to process. The bulging portion 4bb may have a shape other than the V shape. Also in this case, the inner peripheral surface of the pocket 4a can be brought into contact at a plurality of points on one side in the circumferential direction.

  The cage 4 may be integrally formed over the entire circumference, or may be composed of a plurality of segments divided in the circumferential direction, and these segments may be combined with each other, or The segments may remain separated from each other.

  The cage 4 is made of, for example, a steel plate. When it is made of a steel plate, it can be manufactured by punching a hole to be the pocket 4a by press working and then bending a portion to be the bulging portion 4bb into a predetermined shape. The steel plate is suitable for the material of the cage 4 because it is strong and easy to process. The cage 4 may be made of a material other than a steel plate.

  In this slewing bearing, the bearing type is a four-point contact ball bearing and the balls 3 are arranged in double rows, so that the rated load is large while the configuration is simple. In the simple calculation, the static load rating is twice that of the single-row case. When the balls 3 are in a double row, the axial width w of the cage 4 is widened, but it is not doubled as compared with a single row. Therefore, the rated load can be increased without increasing the axial width w of the cage 4 too much. Since the balls 3 are securely held by the cage 4, the balls 3 are not scattered by the advance and delay of the balls 3, and the balls 3 can always be held at equal intervals.

Since the inner peripheral surface of the pocket 4a of the cage 4 contacts the ball 3 at two points P1 and P2 on one side in the circumferential direction, the force applied from the ball 3 to the cage 4 is dispersed, and the ball of the cage 4 The stress at the contact portion is reduced. For this reason, even if the dimension a from the axial end of the cage 4 to the pocket 4a is narrowed or the minimum width b of the column portion 4b of the cage 4 is narrowed, the cage 3 is moved to the cage 4 due to the advance and delay of the ball 3. Can withstand the added forces. Therefore, the axial width w of the cage 4 can be reduced to reduce the axial dimension of the bearing, and the rated load can be further increased by increasing the number of balls by reducing the pitch p between balls. It is.
In addition, if the inner peripheral surface of the pocket 4a is configured to come into contact with the ball 3 at two points P1 and P2 on one side in the circumferential direction, the area where the ball 3 and the cage 4 are close to each other is increased. Since a large amount of lubricating oil can be retained widely in the vicinity, the lubricity of the bearing is good. Therefore, fretting is unlikely to occur even if the rocker is frequently swung within a narrow turning range under the condition of receiving a variable load.

  As described above, this slewing bearing can reduce the weight in the axial direction, reduce the weight, increase the rated load, and prevent fretting. The slewing bearing 21 (FIG. 6) or the slewing bearing 22 (FIG. 6) for nacelle yaw support is suitable. Other than wind turbines for wind power generation, it can be applied to construction machines such as hydraulic excavators and cranes, rotary tables for machine tools, parabolic antennas, and the like.

  In the above embodiment, the balls 3 are in a double row, but may be in a single row. Moreover, although the bulging part 4bb of the pillar part 4b of the retainer 4 is shaped to bulge to the outer diameter side, it may be shaped to bulge to the inner diameter side.

It is sectional drawing of the slewing bearing concerning embodiment of this invention. It is the top view which expand | deployed some cages of the rotation bearing. FIG. 3 is a sectional view taken along line III-III in FIG. 2. It is IV-IV sectional drawing of FIG. It is the perspective view which notched and represented a part of example of the windmill for wind power generation. It is a fractured side view of the wind turbine for wind power generation. It is explanatory drawing of the change of the shape of a holder | retainer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inner ring 1a, 1b ... Inner ring raceway surface 1aa, 1ab, 1ba, 1bb, 2aa, 2ab, 2ba, 2bb ... Curved surface 2 ... Outer ring 2a, 2b ... Outer ring raceway surface 3 ... Ball 4 ... Cage 4a ... Pocket 4b ... Column Part 4bb ... Swelling parts 21, 22 ... Slewing bearing

Claims (7)

A plurality of balls held by a cage are interposed between the grooved raceway surfaces of the inner ring and the outer ring, and the raceways of the inner ring and the outer ring are formed by two curved surfaces respectively positioned on both sides of the groove bottom, In the slewing bearing in which the ball is in contact with the curved surfaces of the raceway surface of the inner and outer rings and contacts four points
The cage is in the shape of a belt curved in an arc along each track surface, and pockets for holding the balls are formed side by side in the circumferential direction, and the shape of the inner peripheral surface of each pocket is A slewing bearing having a shape in contact with the ball at a plurality of points on one side of the inner circumferential surface of the cage in the circumferential direction.   In Claim 1, the shape of the cross section along the cage axial direction of the pillar portion, which is the portion between the pockets in the cage, is linear in both side portions, and a bulging portion that swells to the outer diameter side or inner diameter side in the middle portion. A slewing bearing.   The slewing bearing according to claim 2, wherein a shape of a cross section of the bulging portion along a cage axial direction is V-shaped.   4. The slewing bearing according to claim 1, wherein the cage is made of a steel plate.   5. The slewing bearing according to claim 1, wherein a raceway surface on which the ball is interposed is provided in a double row.   6. The slewing bearing according to claim 1, wherein the blade of the wind turbine is pivotally supported with respect to the main shaft so as to be rotatable about an axis substantially perpendicular to the main shaft axis.   The slewing bearing according to claim 1, wherein the nacelle of the wind turbine is pivotally supported with respect to the support base.

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