Ball bearing

Abstract

To provide a ball bearing with high high-speed rotation performance, capable of being manufactured at low cost by using an inexpensive resin material.SOLUTION: A ball bearing comprises: an inner ring having an inner ring raceway surface; an outer ring having an outer ring raceway surface; a plurality of balls provided between the inner ring raceway surface and the outer ring raceway surface; and a resin holder that holds the plurality of balls at a predetermined interval in a circumferential direction. The holder comprises an annular main part located on one axial side of the balls, and a plurality of pillar parts protruding axially at a predetermined interval in the circumferential direction from the main part, where a pocket part is provided between adjacent pillar parts so as to be able to hold the balls. The pillar parts are provided with a guide part on a radially outer side so as to be able to contact the outer ring raceway surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention particularly relates to a ball bearing adapted for high speed rotation. [Background technology]

[0002] A ball bearing is a rolling bearing having balls as rolling elements, and includes an inner ring, an outer ring, the rolling elements, and a cage that holds the rolling elements rotatably. Crown-type cages have traditionally been used for the cage, as they can be inexpensively molded from resin and balls can be easily installed in them. Crown-type cages have multiple pockets for holding balls formed at regular intervals along the circumferential direction as recesses recessed from one axial end of an annular body.

[0003] When a ball bearing equipped with a crown cage is rotated at high speed by a high-speed motor, the crown cage is easily deformed in the direction in which the recesses open due to centrifugal force. The deformed crown cage may melt or damage the outer ring due to frictional heat caused by contact with the outer ring of the bearing. For this reason, measures have been taken to reduce the centrifugal force acting on the crown cage, such as making the columns thinner, thinner, or shorter, or using expensive, high-strength resin materials.

[0004] Patent Document 1 discloses a bearing equipped with a crown-type cage which includes a circular main portion, a number of column portions which protrude axially from the main portion at a predetermined interval in the circumferential direction, each column portion having a pair of claw portions spaced apart from each other at their tip portions, and a spherical pocket capable of holding a ball between adjacent column portions, in which the outer peripheral surface of the column portions, including the pair of claw portions, is formed so that it is positioned further inward than the outer peripheral surface of the main portion, thereby suppressing deformation due to centrifugal force caused by the high-speed rotation of the crown-type cage, and even if the crown-type cage is deformed by centrifugal force, it is less likely to come into contact with the components that make up the ball bearing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2021-139410 A Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 aims to form a ball bearing with high high-speed rotation performance, and in particular, since it is assumed that the rolling body load is applied approximately evenly, such as in motor support, a hollowed-out portion is formed in the column to reduce the volume of the column evenly, thereby reducing the centrifugal force and reducing the deflection of the column. Therefore, when assuming another application in which the rolling body load is uneven, there is a problem that the column may not be able to withstand the pushing and pulling force of the balls due to the application of an eccentric load to the ball bearing, which causes a speed difference in the revolution speed of the balls. In this respect, it is possible to improve to some extent by using a high-strength resin, but there is a problem that the effect is limited and the manufacturing cost is high.

[0007] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a ball bearing that can be manufactured at low cost using inexpensive resin material and has excellent high-speed rotation performance. [Means for solving the problem]

[0008] The above object of the present invention can be achieved by the following configuration. (1) A bearing comprising an inner ring having an inner ring raceway surface, an outer ring having an outer ring raceway surface, a plurality of balls provided between the inner ring raceway surface and the outer ring raceway surface, and a resin cage that holds the plurality of balls at predetermined intervals in the circumferential direction, The retainer is a main portion having an annular shape located on one side of the axial direction of the ball; A plurality of pillar portions protruding in an axial direction at predetermined intervals in a circumferential direction from the main portion; and a pocket portion capable of holding the ball is provided between adjacent column portions, The column portion is provided with a guide portion on a radially outer side thereof that can contact the outer ring raceway surface. ball bearings. Effect of the Invention

[0009] According to the present invention, a ball bearing having excellent high-speed rotation performance can be manufactured at low cost using inexpensive resin material. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view of a ball bearing according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a view of the ball bearing shown in FIG. [Diagram 3] FIG. 3 is a view of the cage in FIG. 2 taken along the line B. FIG. [Figure 4] FIG. 4 is a view of the cage according to the second embodiment taken along the line B. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (First embodiment) A deep groove ball bearing according to a first embodiment of the present invention will be described in detail below with reference to Fig. 1 to Fig. 3. Fig. 1 is a cross-sectional view of the ball bearing according to the first embodiment of the present invention. Fig. 2 is a view taken along the arrow A of the ball bearing in Fig. 1. Fig. 3 is a view taken along the arrow B of the cage in Fig. 2.

[0012] As shown in Figure 1, the deep groove ball bearing (ball bearing) 10 of this embodiment comprises an outer ring 11 having an outer ring raceway surface 11a on its inner peripheral surface, an inner ring 12 having an inner ring raceway surface 12a on its outer peripheral surface, a plurality of balls 13 arranged between the outer ring raceway surface 11a and the inner ring raceway surface 12a, and a retainer 20 that holds the balls 13 so that they can roll freely. Balls 13 and cage 20 are disposed in annular space 15 formed between outer ring 11 and inner ring 12. Annular space 15 is also referred to as the inside of the bearing. Seal members (not shown) may be provided on both axial sides of ball bearing 10 to prevent grease inside the bearing from leaking to the outside and to prevent foreign matter outside the bearing from entering the inside of the bearing. This ball bearing 10 is suitable for use as a bearing for a shaft that rotates at high speed in, for example, dental air turbines, cleaners, turbochargers, etc.

[0013] In the description of this embodiment, the axial direction is the direction along the center line (central axis) (not shown) of each of the outer ring 11, the inner ring 12, and the cage 20. The axial direction also includes a direction parallel to the center line. The radial direction is the direction perpendicular to the center line of each of the outer ring 11, the inner ring 12, and the cage 20. The circumferential direction is the direction along the circumferential direction centered on the center line of each of the outer ring 11, the inner ring 12, and the cage 20.

[0014] The outer ring 11 has a pair of shoulders 11b, 11b on both axial sides of an outer ring raceway surface 11a. The inner ring 12 has a pair of shoulders 12b, 12b on both axial sides of an inner ring raceway surface 12a. Outer ring raceway surface 11a and inner ring raceway surface 12a are both formed symmetrically with respect to a plane that is perpendicular to the center line and passes through center O of ball 13. In addition, outer ring raceway surface 11a and inner ring raceway surface 12a have radii that are slightly larger than half diameter DC of ball 13. The diameters at groove center position C of the outer ring raceway surface 11a and the inner ring raceway surface 12a are called groove bottom diameters DA1 and DB1, respectively, and the sum of the groove bottom diameters DA1 and DB1 of the outer ring 11 and the inner ring 12 divided by 2 is called pitch circle diameter PCD. Also, the inner diameter at shoulder portion 11b of the outer ring 11 is called outer ring shoulder diameter DA2. This configuration can be seen in FIG. 1.

[0015] The cage 20 is made of a synthetic resin material such as polyamide resin, polyacetal resin, polyphenylene sulfide, polyether ether ketone, polyimide, etc., and is manufactured by injection molding. Note that glass fiber, carbon fiber, aramid fiber, etc. may be added to the resin material as a reinforcing material.

[0016] The retainer 20 comprises a circular main portion 21, a plurality of pillar portions 22 protruding axially at predetermined intervals circumferentially from the main portion 21, pocket portions 23 formed between adjacent pillar portions 22 in which balls 13 are accommodated, a guide portion 24 arranged at the axial tip side of the pillar portions 22, and a protrusion portion 25 arranged at the axial base end side of the pillar portions 22. Guide portion 24 and protrusion portion 25 each protrude radially outward from the outer surface of column portion 22 toward outer ring raceway surface 11a, and the axial spacing between them is shorter than diameter DC of ball 13. As a result, at least a portion of guide portion 24 and protrusion portion 25 are disposed inside outer ring raceway surface 11a. This configuration can be seen in Figures 1 and 2.

[0017] The main portion 21 is formed in a circular ring shape such that the main portion outer diameter D1 of its outer peripheral surface is smaller than the outer ring shoulder diameter DA2 of the shoulder portion 11b of the outer ring 11, and its radial thickness is formed to a thickness that allows it to be placed in the annular space 15, and it is positioned on the other axial side of the bearing interior 15. The main portion 21 is provided with an axial column portion 22 facing one axial side, and a first cutout portion 26 is recessed into the end face on the other axial side, facing the column portion 22. This configuration can be seen in FIG.

[0018] The pillar portions 22 are columnar members extending in the axial direction from the main portion 21 toward one axial side inside the bearing 15, and a plurality of them are provided lined up at predetermined intervals along the annular main portion 21. The column portion 22 is provided with a guide portion 24 and a protrusion portion 25 on the radially outer side, and a second notch portion 27 cut out in the axial direction from one side to the other on the radially inner side. That is, the column portion 22 extends in the axial direction radially outside the pitch circle diameter PCD. This configuration can be seen in Figures 1 and 2.

[0019] The guide portion 24 is provided so as to protrude radially outward from the tip of the column portion 22 toward the outer ring raceway surface 11a. The guide portion 24 has a guide surface 24a extending in an arc shape along the outer ring raceway surface 11a when viewed in the axial direction, a pair of inclined surfaces 24b, 24b formed on both circumferential ends of the guide surface 24a, and a third notch 28 cut out from the axially opposite side of the guide surface 24a.

[0020] A guide portion outer diameter D2, which is the diameter of an imaginary circle connecting the outer circumferential tip ends of the guide surface 24a, is smaller than a groove bottom diameter DA1 of the outer ring raceway surface 11a. The guide surface 24a extends in an arc shape from the tip of the column portion 22 along the extension direction of the outer ring raceway surface 11a. At this time, when the ball bearing 10 is in a non-rotating stationary state, a radial gap h1 is formed between the guide surface 24a and the outer ring raceway surface 11a. This configuration can be seen in FIG. 1.

[0021] The inclined surfaces 24b, 24b are inclined surfaces formed on both circumferential ends of the guide surface 24a, and are surfaces that are smoothly inclined in a direction away from the outer ring raceway surface 11a. For this configuration, please refer to Figure 2, etc.

[0022] The third cutout portion 28 is formed by cutting out the surface of the guide portion 24 on the axially opposite side that does not contact the outer ring raceway surface 11a along the shape of the guide surface 24a. This makes it easier for the guide surface 24a to elastically deform in a direction perpendicular to the outer ring raceway surface 11a, and allows the guide portion 24 to be made lighter.

[0023] The protrusion 25 is provided so as to protrude radially outward from the base end of the column portion 22 toward the outer ring raceway surface 11a, and is formed in a smooth mountain shape that is axially shorter than the guide portion 24. At this time, the protrusion outer diameter D3 indicating the radial height of the protrusion 25 is formed so as to protrude toward the outer ring raceway surface 11a beyond the shoulders 11b, 11b of the outer ring 11. In other words, the protrusion outer diameter D3 is larger than the outer ring shoulder diameter DA2. This configuration may be seen in Figures 1 and 2. The protrusions 25 are arranged at equal intervals along the annular main portion 21, and are arranged near the circumferential outer side of the base end of the column portion 22. This configuration can be seen in FIG.

[0024] According to this configuration, the protrusion 25 is positioned within the outer ring raceway 11a, and when the retainer 20 moves axially, it comes into contact with the other end of the outer ring raceway 11a, thereby preventing the retainer 20 from coming out of the ball bearing 10.

[0025] The pockets 23 are formed between a plurality of pillars 22 arranged at predetermined intervals along the annular main portion 21. The balls 13 arranged inside the bearing 15 are housed in each pocket 23 and held so as to be able to roll freely.

[0026] 2, the radial direction of pocket portion 23 is defined by contact surface 23a, which is formed by curving the surface extending in the radial direction of column portion 22 in an arc shape from inner ring 12 toward outer ring 11 so as to embrace ball 13. At this time, when ball bearing 10 is in a stationary state, a radial gap h2 is formed between contact surface 23a and ball 13.

[0027] 3, the other axial end of the pocket portion 23 is closed by an annular main portion 21 provided to connect the base ends of adjacent column portions 22. On the other hand, an opening 29 is formed at one axial end of the pocket portion 23. The opening 29 opens in parallel by arranging in parallel the pillars 22 whose tip ends are formed in a straight line from the groove center position C. In other words, the pocket 23 is not curved to hold the ball 13 on the opening 29 side, which is one side in the axial direction, unlike the radial direction. According to this configuration, it is possible to suppress deformation when centrifugal force acts, while maintaining the performance of retainer 20 in retaining balls 13. This configuration may be seen in FIG.

[0028] In the above-described configuration, when the ball bearing 10 is in a stationary state, the relationship between the radial gap h1 formed between the guide surface 24a and the outer ring raceway surface 11a, the radial gap h2 formed between the contact surface 23a and the balls 13, and the radial gap h3 formed between the shoulder portion 11b of the outer ring 11 and the retainer 20 is h1>h3>h2. The gap h3 is expressed as (outer ring shoulder diameter DA2-main portion outer diameter D1) / 2.

[0029] (Action and Effects) According to the ball bearing 10 configured as described above, when the guide portion 24 of the cage 20 is deformed radially outward by the centrifugal force acting due to the high-speed rotation of the ball bearing 10, the guide surface 24a smoothly contacts the outer ring raceway surface 11a. Further, the inclined surfaces 24b, 24b can secure a space for smoothly supplying lubricating oil between the outer ring raceway surface 11a and the guide surface 24a at the circumferential end of the guide surface 24a.

[0030] Further, the cage 20 functions as a ball guide positioned by the balls 13 when the ball bearing 10 is in a stationary state or rotating at a low speed. On the other hand, when the ball bearing 10 rotates at high speed, the cage 20 functions not only as a ball guide but also as a groove guide that supports the column portion 22 with the guide portion 24.

[0031] Specifically, during low-speed rotation, since h1 > h2, the cage 20 rotates as a ball guide and rotates at low torque without contact resistance with the outer ring 11. In contrast, when the ball bearing 10 starts to rotate at high speed, the column portion 22 receives centrifugal force and the guide portion 24 tilts toward the outer ring raceway surface 11a side, so the relationship of h1 > h2 of the cage 20 gradually changes to h1 < h2. When the ball bearing 10 rotates even faster, the guide portion 24 of the cage 20 contacts the outer ring raceway surface 11a and enters a support state where h1 = 0, and rotates with outer ring guidance. According to this configuration, the radial outward deflection of the column portion 22 due to centrifugal force can be supported by the sliding of the guide portion 24 on the outer ring raceway surface 11a. Therefore, the high-speed rotation of the cage 20 is stabilized, and breakage of the cage 20 due to excessive deformation can be prevented.

[0032] Further, the cage 20 is lightened by removing material with the first notch 26, the second notch 27, and the third notch 28. For this reason, the centrifugal force acting on the cage 20 can be reduced. Further, the first notch 26 formed in the annular main portion also has the effect of preventing sink marks that occur when the cage 20 is resin molded.

[0033] (Second Embodiment) A second embodiment of the cage 20 will be described with reference to Fig. 4, focusing on differences from the above-mentioned example. Fig. 4 is a view of the cage of the second embodiment as seen in the direction of arrow B. The cage 20 of the second embodiment may be configured such that the protrusions 30 extend along the circumferential width of the base ends of the pillars 22, as shown in FIG. This configuration more reliably prevents balls 13 arranged inside bearing interior 15 from coming off cage 20. The circumferential length of protrusions 30 and the radial length of protrusions can be freely designed within a range that facilitates the assembly of ball bearing 10 and prevents balls 13 from coming off.

[0034] The present invention is not limited to the above-described embodiments, and can be modified and improved as appropriate.

[0035] As described above, the present specification discloses the following: (1) A bearing comprising an inner ring having an inner ring raceway surface, an outer ring having an outer ring raceway surface, a plurality of balls provided between the inner ring raceway surface and the outer ring raceway surface, and a resin cage that holds the plurality of balls at predetermined intervals in the circumferential direction, The retainer is a main portion having an annular shape located on one side of the axial direction of the ball; A plurality of pillar portions protruding in an axial direction at predetermined intervals in a circumferential direction from the main portion; and a pocket portion capable of holding the ball is provided between adjacent column portions, The column portion is provided with a guide portion on a radially outer side thereof that can contact the outer ring raceway surface. ball bearings. According to this configuration, the outer ring raceway surface can be supported by the guide portion when the ball bearing rotates at high speed, so that a ball bearing with high high-speed rotation performance can be manufactured at low cost using inexpensive resin material.

[0036] (2) The guide portion has a guide surface extending in a circumferential direction, and inclined surfaces disposed at both circumferential ends of the guide surface and spaced apart from the outer ring raceway surface toward the outside in the circumferential direction. A ball bearing as described in (1). According to this configuration, lubricating oil can be easily supplied between the guide surface and the outer ring raceway surface.

[0037] (3) The column portion is provided with a protrusion protruding toward the outer ring raceway surface at a base end portion on the radially outer side. A ball bearing according to (1) or (2). According to this configuration, the cage can be reliably prevented from coming out of the ball bearing.

[0038] (4) The cage is formed so that a radial gap h1 formed between the guide portion and the outer ring raceway surface when the cage is not rotating is larger than a radial gap h2 formed between the pocket portion and the ball. The ball bearing according to any one of (1) to (3). According to this configuration, the cage comes into contact with the outer ring raceway surface only when the ball bearing is rotating at high speed, thereby improving economy.

[0039] (5) The column portion has a straight parallel portion formed on the tip side from the center position of the ball, The opening of the pocket portion is formed by a pair of the parallel portions. The ball bearing according to any one of (1) to (4). According to this configuration, the assembly work of the ball bearing becomes easier.

[0040] (6) The guide portion is provided at a radially outer tip portion of the column portion, The ball bearing according to any one of (1) to (5). According to this configuration, when the ball bearing rotates at high speed, the guide portion smoothly comes into contact with the outer ring raceway surface. [Explanation of symbols]

[0041] 10 ball bearings 11 Outer ring 11a Outer ring raceway 11b Shoulder 12 Inner Circle 12a Inner ring raceway surface 12b Shoulder 13 balls 15 Annular space (inside bearing) 20 Retainer 21 Main Section 22 Pillar section 23 Pocket 23a Contact surface 24 Guide section 24a Guide surface 24b Slope 25 Protrusion 26 First notch 27 Second notch 28 Third notch 29 Opening 30 Protrusion

Claims

1. the bearing comprises an inner ring having an inner ring raceway surface, an outer ring having an outer ring raceway surface, a plurality of balls provided between the inner ring raceway surface and the outer ring raceway surface, and a resin cage that holds the plurality of balls at predetermined intervals in the circumferential direction, The retainer is a main portion having an annular shape located on one side of the axial direction of the ball; A plurality of pillar portions protruding in an axial direction at predetermined intervals in a circumferential direction from the main portion; and a pocket portion capable of holding the ball is provided between adjacent column portions, The column portion is provided with a guide portion on a radially outer side thereof that can contact the outer ring raceway surface. ball bearings.

2. The guide portion has a guide surface extending in a circumferential direction, and inclined surfaces disposed at both circumferential ends of the guide surface and spaced apart from the outer ring raceway surface toward the outside in the circumferential direction.

2. A ball bearing according to claim 1.

3. The column portion is provided with a protrusion portion protruding toward the outer ring raceway surface at a base end portion on the radially outer side.

2. A ball bearing according to claim 1.

4. The cage is formed such that a radial gap h1 formed between the guide portion and the outer ring raceway surface when the cage is not rotating is larger than a radial gap h2 formed between the pocket portion and the ball.

2. A ball bearing according to claim 1.

5. The column portion has a straight parallel portion formed on a tip side from a center position of the ball, The opening of the pocket portion is formed by a pair of the parallel portions.

2. A ball bearing according to claim 1.

6. The guide portion is provided at a radially outer tip portion of the column portion, A ball bearing according to any one of claims 1 to 5.

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