Bearing device

Abstract

To provide a bearing device that allows preload adjustment without dimensional adjustment processing.SOLUTION: A bearing device (1) comprises a bearing (4) and a pressing member (8) that contacts an inner ring (5) of the bearing (4) and applies a preload to one side in the axial direction. The pressing member (8) has a fixation portion (10) fixed to a shaft body (2) and an adjustment portion (9), in which the adjustment portion (9) and the fixation portion (10) are connected by thread portions (9a, 10a) formed on the inner diameter surface of the adjustment portion (9) and the outer diameter surface of the fixation portion (10), and an axial step (D) can be adjusted by screw rotation of the adjustment portion (9) and the fixation portion (10).SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present invention relates to a bearing device having a pressing member that allows preload adjustment without dimensional adjustment processing. [Background technology]

[0002] A common method for increasing the rigidity of the entire bearing device is to apply axial preload to the bearing. One method for applying preload to the bearing is to provide an inner ring retainer cover fixed to the shaft (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] European Patent No. 2710271 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the magnitude of preload is controlled by the amount of lid depression, so when lids are attached to assemblies of the same model, the amount of lid depression must be the same. However, because there is variation in the dimensional accuracy and assembly accuracy of each part of the assembly, it is necessary to measure the relevant dimensions during assembly and perform dimensional adjustment processing of the lid based on the measurement results. During dimensional adjustment processing of the lid, the machine is in a standby state for assembly, which causes a problem of reduced assembly efficiency.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a bearing device that can significantly reduce waiting time during assembly by including a holding member called a holding cover that allows preload adjustment without dimensional adjustment processing. [Means for solving the problem]

[0006] In order to achieve the above object, the bearing device of the present invention is a bearing device that supports a shaft, and includes a bearing and a presser member that contacts the inner ring of the bearing and applies a preload to one side in the axial direction, the presser member has a fixed part and an adjustment part that are fixed to the shaft, the adjustment part and the fixed part are connected by threads formed on the inner diameter surface of the adjustment part and the outer diameter surface of the fixed part, and an axial step can be adjusted by screw rotation of the adjustment part and the fixed part. Here, the step refers to the axial dimension between the contact surface of the presser member that abuts against the inner ring and the contact surface of the shaft.

[0007] According to this configuration, the amount of pressing of the holding member can be adjusted by adjusting the axial step by screwing the threaded portions formed on the inner diameter surface of the adjustment portion and the outer diameter surface of the fixing portion without performing dimensional adjustment processing, thereby significantly reducing waiting time during assembly.

[0008] In the bearing device of the present invention, the thermal expansion coefficient of the shaft body and the pressing member is 10 to 15 × 10 -6 / °C may also be used.

[0009] This configuration makes it possible to prevent the preload from increasing more than necessary or decreasing too much due to changes in the operating conditions of the bearing device, i.e., to maintain the bearing preload at an appropriate level.

[0010] In the bearing device of the present invention, the pressing member may be made of carbon steel for machine structural use.

[0011] According to this configuration, the pressing member can have a thermal expansion coefficient close to that of the shaft body and can be made highly rigid.

[0012] In the bearing device of the present invention, the threads of the threaded portions of the adjustment portion and the fixed portion may be fine threads.

[0013] This configuration can improve the rigidity of the screw portion and the adjustment accuracy of the adjustment portion.

[0014] In the bearing device of the present invention, a hole for inserting a rotation jig may be formed in the end face or outer diameter face of the adjustment portion.

[0015] According to this configuration, by rotating the adjustment portion using a rotation jig such as a pin, the step between the adjustment portion and the fixed portion can be easily adjusted.

[0016] In the bearing device of the present invention, the pressing member may have a position stop member that is screwed into the threaded portion of the fixing portion to fix the axial position of the adjustment portion, and a threaded portion may be formed on the inner diameter surface of the position stop member.

[0017] According to this configuration, the axial position of the adjustment portion can be fixed after the step is adjusted. [Effects of the Invention]

[0018] According to the bearing device of the present invention, preload adjustment is possible without performing dimensional adjustment processing on the pressing member, and waiting time during assembly can be significantly reduced. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a longitudinal sectional view showing an outline of a bearing device according to a first embodiment of the present invention. [Figure 2] 3 is a partially enlarged cross-sectional view showing an outline of a preload applying portion of the bearing device according to the embodiment; FIG. [Figure 3] FIG. 10 is a partial cross-sectional view showing a conventional pressing member for applying preload. [Figure 4A] FIG. 4 is a partial cross-sectional view showing a pressing member before the bearing device according to the embodiment is attached; [Figure 4B] 4 is a partial cross-sectional view showing the pressing member after the bearing device according to the embodiment has been attached. FIG. [Figure 5] FIG. 6 is a partial cross-sectional view showing a pressing member of a bearing device according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a partial cross-sectional view showing a pressing member of a bearing device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The bearing device according to the present invention will be described below using a bearing device for a main shaft of a large wind power generator as an example, but the application of the bearing device according to the present invention is not limited to bearing devices for main shafts of large wind power generators as long as it is applicable.

[0021] First Embodiment A bearing device 1 according to a first embodiment of the present invention will be described. As shown in Figure 1, the bearing device 1 includes a pair of bearings 4, 4 that support a shaft 2, which is the main shaft of a large wind turbine generator, and are installed between a housing 3 and the shaft 2. These bearings 4, 4 are tapered roller bearings that are paired back-to-back. Each bearing 4 is composed of an inner ring 5, an outer ring 6, a plurality of rolling elements 7 interposed between the raceways of the inner and outer rings 5, 6, and a cage (not shown) that holds these rolling elements 7. The bearings 4, 4 are not limited to tapered roller bearings and may be ball bearings, for example.

[0022] In the following description, the direction along the axial direction of the central axis (not shown) of the center of rotation of the bearing device 1 will be referred to as the "axial direction." The axial direction corresponds to the left-right direction in FIG. 1. The direction toward the axial center position of the bearing device 1 will be referred to as the "axial inner side," and the direction away from the axial center position will be referred to as the "axial outer side."

[0023] The opposing end faces of the outer rings 6, 6 of both bearings 4, 4 engage with stepped surfaces 3a, 3b facing the axial direction formed on the inner surface of the housing 3. The axially outer end face of the inner ring 5 of one (left) bearing 4 engages with a stepped surface 2a formed integrally with the outer peripheral surface of the shaft 2. The axially outer end face of the inner ring 5 of the other (right) bearing 4 engages with a pressing member 8 attached to the shaft 2. The pressing member 8 is pressed against the shaft 2 by a bolt 20 (Figure 2) that screws into the shaft 2. This applies a fixed-position preload to the bearing 4.

[0024] The inner ring 5 has a raceway surface 5b formed on its outer periphery, which is a tapered surface, with a large rib 5c and a small rib 5d on the larger-diameter side and smaller-diameter side of the raceway surface 5b, respectively. The outer periphery of the large rib 5c is a cylindrical surface, and the outer periphery of the small rib 5d is a tapered surface parallel to the raceway surface 5b. The outer ring 6 has a raceway surface 6b formed on its inner periphery that faces the raceway surface 5b of the inner ring 5, and is flangeless. The outer periphery of the rolling elements 7, which are tapered rollers, is formed as a rolling surface and is able to roll freely between the raceway surfaces 5a, 6a.

[0025] The inner ring 5 and the outer ring 6 are made of, for example, high-carbon chromium bearing steel such as JIS standard SUJ2, alloy steel for machine structures such as SCM420, or carbon steel for machine structures such as S53C, while the rolling elements 7 are made of an iron-based metal material, ceramic, etc. Iron-based metal materials include bearing steel used in rolling bearings, carburized steel, carbon steel for machine structures, cold-rolled steel, hot-rolled steel, etc.

[0026] The inner ring 5 restrains the rolling elements 7 from moving in the axial direction to either side of the raceway surface 5b by using the large rib 5c and small rib 5d. In contrast, the outer ring 6 has no rib and is therefore a non-restraining raceway ring that does not restrain the rolling elements 7 from moving from the raceway surface 6b toward the larger diameter side. However, the outer ring 6 itself restricts the rolling elements 7 from moving from the raceway surface 6b toward the smaller diameter side.

[0027] As shown in Figure 2, the magnitude of the preload is controlled by the amount of pressing C of the pressing member 8. The amount of pressing C refers to the axial dimension between the axial end face 2b of the shaft 2 and the abutment surface 8b of the pressing member 8 that faces the end face 2b when the axial end face 5a of the inner ring 5 abuts against the abutment surface 8a of the pressing member 8 that faces the end face 5a. As shown in Figure 3, conventional pressing members 8 are made of a single member, so when adjusting the amount of pressing C to the desired dimension, it was necessary to adjust the dimension of the step D by machining the abutment surface 8a or the abutment surface 8b. Here, the step D refers to the axial dimension between the abutment surface 8a of the pressing member 8 that faces the inner ring 5 and the abutment surface 8b of the shaft 2.

[0028] In contrast, the holding member 8 of the present invention, as shown in Figures 4A and 4B, is composed of an adjustment portion 9 and a fixed portion 10. A threaded portion 9a formed on the inner diameter surface of the adjustment portion 9 and a threaded portion 10a formed on the outer diameter surface of the fixed portion 10 are threadedly engaged with each other, thereby joining the adjustment portion 9 and the fixed portion 10 and forming the holding member 8. A through hole 10b is formed in the fixed portion 10 for a bolt that screws into the shaft body 2. In the illustrated example, both the adjustment portion 9 and the fixed portion 10 are ring-shaped, but the shapes of the adjustment portion 9 and the fixed portion 10 are not limited to this as long as they perform the same function.

[0029] The method for attaching the retaining member 8 will now be described. First, the axial dimension M between the axial end face 2b of the shaft 2 and the axial end face 5a of the inner ring 5 is measured. The value of the required step D is the sum of this axial dimension M and the amount of push-in C (D = C + M), and since the amount of push-in C is a value that is determined in advance depending on the preload to be applied, the value of the required step D is calculated from the measured dimension M. The dimension of the step D is adjusted using the adjustment unit 9 so that it becomes the calculated step D. The retaining member 8 is attached by pressing the adjusted retaining member 8 toward the shaft 2 using the bolt 20 that screws into the shaft 2.

[0030] The dimensions of each component that makes up the bearing device 1 change due to changes in operating conditions such as heat generated during use of the bearing device 1, and the magnitude of the preload changes due to the difference in the dimensional changes. To prevent the magnitude of the preload from changing, it is necessary to make the dimensional changes of the shaft body 2 and the pressing member 8 attached to the shaft body 2 approximately the same. Specifically, the thermal expansion coefficients of the shaft body 2 and the pressing member 8 are set to 10 to 15 × 10 -6 / °C is preferred.

[0031] In wind turbines, spheroidal graphite cast iron such as QT400-18AL is often used as the material for the shaft 2 and the housing 3. The material for the retaining member 8 must have a thermal expansion coefficient close to that of the shaft 2 and high rigidity, so mechanical structural carbon steel, mechanical structural alloy steel, etc. such as S35C, S45C, SCM435, etc. are preferred.

[0032] By using a material for the pressing member 8 that has a thermal expansion coefficient close to that of the shaft body 2 and a high rigidity, it is possible to suppress changes in the preload. In particular, it is preferable that the thermal expansion coefficients of the shaft body 2 and the pressing member 8 are 10 to 15 × 10 -6 / °C, it is possible to prevent the preload from increasing more than necessary or decreasing too much due to changes in the temperature operating conditions of the bearing device 1. In other words, it is possible to maintain the bearing preload at an appropriate level.

[0033] The threads of the threaded portion 9a of the adjustment portion 9 and the threaded portion 10a of the fixing portion 10 are preferably fine threads. By using fine threads, the precision with which the preload is adjusted by the pressing member 8 can be improved.

[0034] According to the above configuration, the dimension of the step D can be adjusted without processing the pressing member 8. By providing the bearing device 1 with a pressing member 8 that allows such preload adjustment, the waiting time during assembly of the bearing device 1 can be significantly reduced.

[0035] <Other embodiments> In the following description, parts corresponding to matters previously described in each embodiment are given the same reference numerals, and duplicated description will be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as the previously described embodiment unless otherwise specified. The same functions and effects are achieved from the same configuration. It is possible to combine not only the parts specifically described in each embodiment, but also parts of the embodiments together, provided that there is no particular problem with the combination.

[0036] <Second embodiment> Next, a bearing device 1 according to a second embodiment of the present invention will be described with reference to Fig. 5. As shown in Fig. 5, a rotation jig hole 12 for rotating the adjustment part 9 is formed in the axial outer end surface of the adjustment part 9 of this bearing device 1. A rotation jig 13 is inserted into this rotation jig hole 12, and a rotational torque is applied to the adjustment part 9 through the rotation jig 13, thereby rotating the adjustment part 9. The rotation jig 13 is, for example, a pin.

[0037] The rotation jig holes 12 may be provided on the outer diameter surface of the adjustment portion 9. Furthermore, the rotation jig holes 12 on the outer end surface or outer diameter surface of the adjustment portion 9 may be provided in multiple locations in the circumferential direction, preferably at equal intervals.

[0038] According to the bearing device 1 of this embodiment, the adjustment portion 9 can be easily rotated using the rotation jig 13 inserted into the rotation jig hole 12, which simplifies the preload adjustment work.

[0039] <Third embodiment> Next, a bearing device 1 according to a third embodiment of the present invention will be described with reference to Fig. 6. As shown in Fig. 6, a positioning member 15 is provided on the inner diameter portion of the axially outer end portion of the adjustment part 9. A threaded portion 15a is formed on the inner diameter surface of the positioning member 15, and is threadedly engaged with the threaded portion 10a of the fixing part 10. The shape of the positioning member 15 is, for example, a ring shape.

[0040] According to the bearing device 1 of this embodiment, after the preload adjustment is completed, the axial position of the adjustment part 9 can be fixed by tightening the position retaining member 15 to the axial end face of the adjustment part 9. This makes it possible to suppress changes in the preload while the bearing device 1 is in use.

[0041] Although the embodiments of the present invention have been described above, the disclosed embodiments are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims rather than the above description, and it is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0042] 1...bearing device, 2...shaft body, 3...housing, 4...bearing, 5...inner ring, 6...outer ring, 7...rolling element, 8...holding member, 8a, 8b...contact surface, 9...adjustment part, 10...fixing part, 12...hole for rotation jig, 13...rotation jig, 15...position stopping member, C...pressure amount, D...step

Claims

1. A bearing device for supporting a shaft, A bearing, a pressing member that contacts the inner ring of the bearing and applies a preload to one side in the axial direction, The pressing member is a fixing portion fixed to the shaft body and an adjustment portion; the adjustment portion and the fixing portion are connected by a thread portion formed on an inner diameter surface of the adjustment portion and an outer diameter surface of the fixing portion, The axial step can be adjusted by screwing the adjustment part and the fixing part together. Bearing device.

2. 2. The bearing device according to claim 1, wherein the thermal expansion coefficient of the shaft body and the pressing member is 10 to 15×10 -6 / °C.

3. 3. The bearing device according to claim 1, wherein the pressing member is made of carbon steel for mechanical construction.

4. 3. The bearing device according to claim 1, wherein the threads of the threaded portions of the adjustment portion and the fixed portion are fine threads.

5. 3. The bearing device according to claim 1, wherein a hole for inserting a rotation jig is formed in an end face or an outer diameter face of the adjustment portion.

6. 3. The bearing device according to claim 1, wherein the pressing member has a position stop member that is threadedly engaged with the threaded portion of the fixing portion to fix the axial position of the adjustment portion, and the position stop member has a threaded portion formed on its inner diameter surface.

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