Jade Axle

Abstract

To realize a ball bearing at low cost that can prevent the occurrence of high-speed whirl phenomenon and suppress heat generation and wear at the contact point between the raceway and balls during high-speed rotation. [Solution] When the relative rotational speed of the inner ring 2 and the outer ring 3 is below a predetermined value, the outer ring 3 and the retainer 5 elastically deform in accordance with the relative rotational speed of the inner and outer rings, such that when the relative rotational speed of the inner ring 2 and the outer ring 3 is below a predetermined value, the relationship between the size α of the pocket clearance Gb formed between the cylindrical surface 7 forming the pocket 6 of the retainer 5 and the ball 4 and the size β of the guide clearance (second radial clearance Ga2) formed between the inner diameter surface 3a of the outer ring 3 and the outer diameter surface 5b of the retainer 5 is α < β, which is the first state, and when the relative rotational speed of the inner and outer rings exceeds a predetermined value, the relationship between α·β is α > β, which is the second state. The retainer 5 has an inclined portion 8 that is inclined in a direction that gradually reduces the diameter of the cylindrical surface 7 radially outward, and this inclined portion 8 is provided continuously on the outer diameter side of the cylindrical surface 7.

Description

Technical Field

[0001] The present invention relates to a ball bearing.

Background Art

[0002] Figs. 12(a) and (b) show schematic cross-sectional views of an existing ball bearing. The ball bearing 100 shown in the figure includes a pair of raceways (inner ring 101 and outer ring 102) that rotate relative to each other around a central axis via a plurality of balls 103 arranged opposite to each other in the radial direction, and an annular cage 104 that holds the plurality of balls 103. A lubricant (not shown), such as grease, is interposed in the annular space between the inner ring 101 and the outer ring 102. The cage 104 is provided with a plurality of pockets 105 that open on the inner diameter surface and the outer diameter surface at intervals in the circumferential direction, and the balls 103 are individually accommodated in each pocket 105. The pocket 105 in the illustrated example is formed by providing a pocket forming surface 105a having a constant diameter cylindrical surface on the cage 104.

[0003] In a neutral state where the center of the pocket 105 and the center of the ball 103 coincide, the cage 104 forms radial clearances 111 and 112 between the outer peripheral surface 101a of the inner ring 101 and the inner peripheral surface 102a of the outer ring 102, respectively, and a circumferential clearance 113 between the ball 103 accommodated in the pocket 105, and is arranged between the inner ring 101 and the outer ring 102. The above-mentioned radial clearances 111 and 112 are also referred to as "guide clearances", and the above-mentioned circumferential clearance 113 is also referred to as "pocket clearance" or "pocket circumferential clearance". Due to the existence of the above various clearances, the cage 104 arranged in the annular space between the inner and outer rings can move in the radial and circumferential directions within the annular space when the ball bearing 100 operates (when the inner ring 101 and the outer ring 102 rotate relative to each other).

[0004] Ball bearings 100 can be broadly classified into two types based on the guide type of the cage 104: raceway-guided type and rolling element-guided type. The raceway-guided type can be further classified into outer ring-guided type and inner ring-guided type. Roughly speaking, the outer ring-guided type is a type in which the cage 104, when in a neutral state, preferentially contacts the outer ring 102 when it moves, while the rolling element-guided type is a type in which the cage 104, when in a neutral state, preferentially contacts the balls 103 when it moves.

[0005] During operation of the ball bearing 100 described above, the cage 104 may experience abnormally high-speed runout (runout at several times the cage's rotation frequency or more), also known as high-speed whirling. When high-speed whirling occurs, it can cause problems such as abnormal noise, vibration, increased torque, torque fluctuations, and heat generation. High-speed whirling is said to be caused by frictional forces resulting from radial contact between the raceway ring and the cage 104, or frictional forces resulting from circumferential contact between the cage 104 (or its pocket-forming surface 105a) and the balls 103. The mechanism of high-speed whirling caused by contact between the cage 104 and the balls 103 will be briefly explained below based on Figures 12(a) and (b).

[0006] First, as the ball bearing 100 operates, as shown in Figure 12(a), when the cage 104 is displaced in the 12 o'clock direction relative to the axis O, the balls 103 positioned at 3 o'clock and 9 o'clock come into contact with the pocket-forming surface 105a of the cage 104 at the 6 o'clock position. At this time, assuming the inner ring 101 is rotating clockwise, a radial frictional force F is generated between the balls 103 and the cage 104, causing the cage 104 to displace in the 3 o'clock direction. When the cage 104 is displaced by this frictional force F, as shown in Figure 12(b), the balls 103 positioned at 12 o'clock and 6 o'clock come into contact with the pocket-forming surface 105a of the cage 104 at the 9 o'clock position. Consequently, a radial frictional force F is generated, causing the cage 105 to displace in the 6 o'clock direction. Subsequently, as the contact and friction between the retainer 104 and the ball 103 are repeated as described above, the retainer 104 swings at high speed in the same direction as the rotation of the inner ring 101.

[0007] Although a diagrammatic explanation is omitted, when a high-speed whirling phenomenon occurs due to the frictional force (radial frictional force) generated by the radial contact between the raceway and the retainer, the retainer swings at high speed in the opposite direction to the rotation of the inner ring.

[0008] The applicant noted that the radial frictional force generated at the contact point between the cage and the balls and the radial frictional force generated at the contact point between the cage and the raceway ring are in opposite directions when a ball bearing is in operation. Based on this observation, the applicant has proposed a ball bearing that allows the cage to contact both the balls and the raceway ring as the cage moves within the annular space during operation (see Patent Document 1 below). According to the ball bearing of Patent Document 1, the frictional force generated at one of the two contact points can be mitigated by the frictional force generated at the other, thereby preventing as much as possible the occurrence of the high-speed whirling phenomenon of the cage caused by the frictional force generated by the contact between the balls and the cage, or the frictional force generated by the contact between the raceway ring and the cage. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2024-32359 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] To realize the ball bearing described in Patent Document 1, it is necessary to satisfy a predetermined relational expression that includes the following parameters: (1) the size of the radial guide clearance (= "clearance width"; the same applies hereinafter) formed between the guide surface of the raceway ring and the guided surface of the cage, (2) the size of the pocket clearance formed between the ball and the cylindrical pocket-forming surface of the cage, (3) the roundness of the guide surface, and (4) the roundness of the guided surface. In reality, however, it is necessary to set (change) the roundness of the guide surface and the guided surface according to the lubrication conditions and temperature conditions of the ball bearing, which increases the difficulty of the design and also requires meticulous roundness control. Therefore, realizing the ball bearing described in Patent Document 1 is not easy, and there are concerns that it will require a lot of effort and cost to realize.

[0011] Furthermore, when the cage comes into contact with the balls during the operation of a ball bearing, the lubricant adhering to the surface of the balls is scraped off by the cage. Therefore, if contact between the cage and the balls is repeated, especially during high-speed rotation of the raceway ring where lubrication conditions are severe, the lubricant on the ball surface becomes insufficient, increasing the likelihood of abnormal heat generation and wear at the contact point between the raceway ring and the balls. Consequently, to avoid such problems, it is desirable to reduce the frequency of contact between the cage and the balls during high-speed rotation as much as possible, but Patent Document 1 does not disclose or suggest any technical means that can meet this requirement.

[0012] In view of the above circumstances, the present invention aims to realize a ball bearing at low cost that can prevent the occurrence of high-speed whirring in the cage as much as possible, and in particular suppress heat generation and wear at the contact area between the raceway and the balls during high-speed rotation. [Means for solving the problem]

[0013] The present invention, devised to achieve the above objective, is a ball bearing comprising an inner ring and an outer ring that rotate relative to each other via a plurality of balls, an annular cage that individually holds the balls, and a lubricant interposed in the annular space between the inner ring and the outer ring. The ball is housed in a pocket defined by a cylindrical surface formed in the holder. When the relative rotational speed of the inner and outer rings is below a predetermined value, the outer ring and the cage elastically deform in accordance with the relative rotational speed of the inner and outer rings, such that the relationship between the size of the pocket clearance α formed between the balls and the cage and the size of the guide clearance β formed between the inner diameter surface of the outer ring and the outer diameter surface of the cage is α < β, and when the relative rotational speed exceeds the predetermined value, the relationship is α > β, thus the outer ring and the cage elastically deform in accordance with the relative rotational speed of the inner and outer rings. The retainer has an inclined portion that is angled in a direction that gradually reduces the diameter of the cylindrical surface radially outward, and this inclined portion is provided continuously on the outer diameter side of the cylindrical surface.

[0014] First, in the ball bearing according to the present invention, the first state, where the relationship between the size of the pocket clearance α and the size of the guide clearance β is α < β, can be described as a so-called rolling element guide state, in which the cage preferentially contacts the balls when the cage moves within the annular space due to the operation of the ball bearing (relative rotation of the inner ring and outer ring). The second state, where the relationship between α and β is α > β, can be described as a so-called outer ring guide (raceway guide) state, in which the cage preferentially contacts the outer ring when the cage moves within the annular space. The ball bearing according to the present invention is in the first state when the relative rotation speed of the inner ring and outer ring is below a predetermined value (specifically, below a predetermined value less than the maximum speed), such as when the relative rotation of the inner ring and outer ring has stopped, and is in the second state when the relative rotation speed exceeds a predetermined value, such as when the inner ring and outer ring are rotating at the maximum speed. Therefore, the cage guide mode during high-speed rotation can be an outer ring guide, which reduces the frequency of contact between the cage and the balls compared to the rolling element guide. Reducing the frequency of contact between the cage and the balls prevents the lubricant adhering to the ball surface from being scraped off by the cage. Therefore, even at high rotational speeds, problems such as abnormal heat generation and wear at the contact points between the inner and outer rings and the balls become less likely to occur.

[0015] Furthermore, if the retainer has an inclined portion that gradually reduces the diameter (opening dimension) of the cylindrical surface toward the radially outward direction, and this inclined portion is continuously provided on the outer diameter side of the cylindrical surface, then in the first state described above, where the retainer's guide type is a so-called rolling element guide, the direction of the frictional force generated when the balls contact the inclined portion can be set to a direction inclined at a predetermined angle with respect to the radial direction. In this case, the driving force of the high-speed whirl phenomenon can be made smaller than in the case described with reference to Figure 12 (when radial frictional force is generated at the contact portion). Therefore, the occurrence of the high-speed whirl phenomenon of the retainer can be suppressed or prevented, especially at low rotational speeds.

[0016] Furthermore, the ball bearing according to the present invention achieves the above-mentioned effects by elastically deforming the outer ring and cage in accordance with the relative rotational speed of the inner ring and outer ring. In achieving the above-mentioned effects, it is not necessary to meticulously control the roundness of the guide surface of the raceway ring and the guided surface of the cage (for example, the inner diameter surface of the outer ring and the outer diameter surface of the cage). Therefore, it can be easily realized compared to conventional ball bearings, which require meticulous control of the roundness of the guide surface and the guided surface according to lubrication conditions, temperature conditions, etc.

[0017] The retainer can be constructed by integrally having an annular base on which multiple cylindrical surfaces are provided at circumferential intervals, and a guided portion located radially outward from the base and guided by the inner diameter surface of the outer ring in the second state. In this case, the inclined portion can be provided on the guided portion.

[0018] The guided portion described above can be formed, for example, in an arc shape positioned between two adjacent cylindrical surfaces in the circumferential direction. In this case, if the axial width of the guided portion is made smaller than the diameter of the cylindrical surface, the deformability of the guided portion (and the retainer having it) is increased, making it possible to smoothly transition between the first state and the second state.

[0019] The axial width of the portion inside the object to be guided provided in the cage may be equal to or greater than the diameter of the cylindrical surface. In this case, if a plurality of axial grooves are provided at intervals in the circumferential direction on the outer diameter surface of the cage, the plurality of portions inside the object to be guided can be arranged at intervals in the circumferential direction by the plurality of axial grooves.

Effects of the Invention

[0020] As described above, according to the present invention, in addition to being able to prevent, as much as possible, the occurrence of the high-speed whirling phenomenon of the cage, particularly during low-speed rotation, and further the occurrence of abnormal noises and vibrations that may result therefrom, it is possible to reduce the contact frequency between the cage and the balls during high-speed rotation, suppress abnormal heat generation and wear at the contact portions between the inner ring, the outer ring and the balls, and realize a ball bearing at a low cost.

Brief Description of the Drawings

[0021] [Figure 1] It is a partial schematic plan view of a ball bearing according to a first embodiment of the present invention. [Figure 2] It is a cross-sectional view taken along the line A1-A1 of FIG. 1. [Figure 3] (a) FIG. is an overall perspective view of a cage incorporated in the ball bearing of FIG. 1, and (b) FIG. is a partial developed plan view when the cage shown in (a) FIG. is viewed from the radially outer side. [Figure 4] It is an enlarged cross-sectional view taken along the line A2-A2 of FIG. 3. [Figure 5] It is a diagram for explaining the arrangement mode of the outer ring, the balls and the cage in a ball bearing in a no-load state. [Figure 6] It is a diagram schematically showing the state when the balls contact the cage during the operation of the ball bearing of the first embodiment. [Figure 7] It is a schematic longitudinal sectional view of a ball bearing according to a second embodiment of the present invention. [Figure 8] An overall perspective view of a cage incorporated in the ball bearing shown in FIG. 7, and (b) FIG. is a partial developed plan view when the cage shown in (a) FIG. is viewed from the radially outer side. [Figure 9] It is a schematic longitudinal sectional view of a ball bearing according to a third embodiment of the present invention. [Figure 10] (a) is an overall perspective view of the cage incorporated into the ball bearing shown in Figure 9, and (b) is a partial unfolded plan view of the cage shown in Figure (a) as seen from the radially outer side. [Figure 11] Figure 10 shows a modified example of the retainer. [Figure 12] (a) is a schematic cross-sectional view showing the cage of a rolling element-guided ball bearing in a displaced state, and (b) is a schematic cross-sectional view showing the cage of the ball bearing shown in (a) in a further displaced state. [Modes for carrying out the invention]

[0022] Hereinafter, a first embodiment of the present invention will be described with reference to Figures 1-6. Figure 1 is a partial schematic plan view of a ball bearing 1 according to the first embodiment of the present invention, and more specifically, a partial schematic plan view of the ball bearing 1 in an unloaded state (stopped state) where gravity, rotational force, etc., is not acting on the ball bearing 1, and the cage 5 is in a neutral position where the center of the pocket 6 and the center of the ball 4 coincide (neutral state). Figure 2 is a cross-sectional view taken along the line A1-A1 in Figure 1, Figure 3 is an overall perspective view of the cage incorporated into the ball bearing 1, Figure 4 is an enlarged cross-sectional view taken along the line A2-A2 in Figure 3, Figure 5 is a partially enlarged view to explain the arrangement of the outer ring 3, balls 4 and cage 5 in the ball bearing 1 in an unloaded state, and Figure 6 is a schematic diagram showing the state when the balls 4 contact the cage 5 during the operation of the ball bearing 1. The terms "axial direction," "radial direction," and "circumferential direction" used below to indicate direction refer to the direction parallel to the axis O of the ball bearing 1, the radial direction of the circle centered on the axis O, and the circumferential direction of the circle centered on the axis O, respectively.

[0023] The ball bearing 1 shown in Figures 1 and 2 is an angular contact ball bearing comprising a pair of raceway rings (inner ring 2 and outer ring 3) that rotate relative to each other around an axis O while being positioned opposite each other with a radial gap between them, a plurality of balls 4 that are rotatably arranged between the inner ring 2 and the outer ring 3, an annular cage 5 interposed in the annular space between the inner ring 2 and the outer ring 3, and a lubricant such as grease (not shown). The balls 4 contact the arc-shaped inner raceway surface 2b formed on the outer circumferential surface 2a of the inner ring 2 and the arc-shaped outer raceway surface 3b formed on the inner circumferential surface 3a of the outer ring 3 at a contact angle θ. The inner ring 2, outer ring 3 and balls 4 are made of a high-rigidity metal material such as heat-treated bearing steel (high-carbon chromium bearing steel).

[0024] As shown in Figures 1 to 3, the retainer 5 has multiple pockets 6 spaced apart in the circumferential direction (in this case, equally spaced in the circumferential direction). The pockets 6 are defined by forming a cylindrical surface 7 on the retainer 5, and one ball 4 is housed in each pocket 6.

[0025] As shown in Figures 2, 4, and 5, the cage 5 in the neutral position is positioned in the annular space between the inner and outer rings such that it forms radial clearances between itself and the inner ring 2 and the outer ring 3, and also forms a clearance between itself and the balls 4 housed in the pockets 6. Here, a first radial clearance Ga1 is formed between the outer diameter surface 2a of the inner ring 2 and the inner diameter surface 5a of the cage 5, a second radial clearance Ga2 as a "guide clearance" is formed between the inner diameter surface 3a of the outer ring 3 and the outer diameter surface 5b of the cage 5, and a pocket clearance Gb is formed between the cage 5 and the balls 4. With these various clearances set, the cage 5 can move radially and circumferentially when the ball bearing 1 is operating, ensuring good operation of the ball bearing 1.

[0026] As shown in Figures 4 and 5, the cylindrical surface 7 defining the pocket 6 is formed in a cylindrical shape with a constant diameter. The retainer 5 also has an inclined portion 8 that is inclined in a direction that gradually reduces the diameter (opening dimension) of the cylindrical surface 7 toward the radially outward direction, and this inclined portion 8 is provided continuously on the outer diameter side of the cylindrical surface 7. In other words, the outer diameter side end of the cylindrical surface 7 and the inner diameter side end of the inclined portion 8 are connected. Therefore, the pocket gap Gb formed between the ball 4 housed in the pocket 6 and the retainer 5 has a pocket gap with a width in the circumferential direction (pocket circumferential gap) Gb1 and a pocket gap with a width in the radial direction (pocket radial gap) Gb2, as shown in Figure 5.

[0027] As shown in Figure 3, the retainer 5 consists of an annular base 10 which is an annular shape overall and has multiple circular holes 10a that form pockets 6 (the inner diameter side portion) provided at circumferential intervals (here, equally spaced in the circumferential direction), and a guided portion 11 provided radially outside the base 10, whose outer diameter surface is guided to the inner diameter surface 3a of the outer ring 3 in the second state described later. The guided portion 11 in this embodiment has an arc shape and is provided in multiple quantities at circumferential intervals so as to be positioned between two adjacent pockets 6 (forming cylindrical surfaces 7) in the circumferential direction. The circumferential ends of the arc-shaped guided portion 11 are located in the projection plane obtained by projecting the holes 10a radially outward (see Figure 4). With this configuration, the cylindrical surface 7 that forms the pockets 6 is composed of the inner wall surface of the circular holes 10a provided in the annular portion 10, and the inclined portion 8 is composed of the circumferential end 11a of the arc-shaped guided portion 11. Furthermore, the axial width (axial dimension) of the guided portion 11 is smaller than the axial width of the base portion 10 and smaller than the diameter of the cylindrical surface 7.

[0028] The cage 5 having the above configuration employs a resin cage made of resin material such as PA66 resin or phenolic resin. This allows the cage 5 to be elastically deformable due to centrifugal force acting during bearing operation and thermal expansion due to temperature rise during bearing operation. However, in addition to resin cages, the cage 5 can also employ, for example, a "machined cage" which is a machined part of a metal material, or a pressed cage obtained by joining a pair of cage materials that have been press-formed (punched) into a predetermined annular shape.

[0029] In the ball bearing 1 in an unloaded state (stopped state), the size of the first radial clearance Ga1 is larger than the size of the second radial clearance Ga2, which acts as a "guide clearance" (see Figure 2), and furthermore, the size of the second radial clearance Ga2 is larger than the size of the pocket clearance Gb (more specifically, the pocket circumferential clearance Gb1 or the pocket radial clearance Gb2, and here the pocket circumferential clearance Gb1: see Figure 5). Therefore, when the ball bearing 1 is stopped, the first state is one in which the inequality α < β holds, where α is the size of the pocket clearance Gb and β is the size of the second radial clearance Ga2, which acts as a "guide clearance". This first state is maintained when the relative rotational speed of the inner ring 2 and the outer ring 3 (here, the rotational speed of the inner ring 2) is below a predetermined value. In this case, when the cage 5 moves radially as the ball bearing 1 operates, the cage 5 contacts the balls 4 before the inner ring 2 and the outer ring 3. Therefore, when the ball bearing 1 is in the first state described above, the guide type of the cage 5 is what is known as rolling element guide.

[0030] As described above, the pocket 6 of the retainer 5 is formed by a cylindrical surface 7 with a constant diameter, and a continuous inclined portion 8 is provided on the radially outer side of the cylindrical surface 7. Therefore, when the retainer 5 moves radially (during low-speed rotation), the ball 4 comes into contact with the inclined portion 8, as schematically shown in Figure 6. The frictional force F generated at this contact point is in a direction inclined at a predetermined angle with respect to the radial direction, corresponding to the inclination of the inclined portion 8. In this case, unlike the conventional example explained with reference to Figures 12(a) and (b), the directions of the frictional forces F generated at two locations with a circumferential phase difference of 180° are different from each other, so a high-speed whirl phenomenon driven by the frictional force F generated at the contact point between the retainer 5 and the ball 4 becomes less likely to occur.

[0031] In the ball bearing 1, as the relative rotational speed of the inner ring 2 and the outer ring 3 (the rotational speed of the inner ring 2) increases, the outer ring 2 and the cage 5 expand and deform elastically due to the effects of frictional heat generated by friction with lubricant, etc., and the cage 5 further expands and deforms elastically radially outward due to the effects of centrifugal force applied to the cage 5. In the cage 5 of this embodiment, along with the above-mentioned expansion deformation, the circumferential end of the guided portion 11 provided at the outer diameter end elastically deforms radially outward. When the rotational speed of the inner ring 2 exceeds the above-mentioned predetermined value, the relative magnitudes of the pocket clearance Gb (here, both the pocket circumferential clearance Gb1 and the pocket radial clearance Gb2) and the magnitude β of the second radial clearance Ga2 as a guide clearance are reversed, and the bearing transitions to a second state where the inequality α > β holds. When the cage 5 moves radially in this state, the cage 5 contacts the outer ring 3 before the balls 4. Therefore, when the ball bearing 1 is in the second state described above, the guide type of the cage 5 is what is known as an outer ring guide.

[0032] When the cage 5 is guided by an outer ring, the frequency of contact between the cage 5 and the balls 4 can be reduced compared to when it is guided by rolling elements. If the frequency of contact between the cage 5 and the balls 4 is reduced, lubricants such as grease adhering to the surface of the balls 4 are less likely to be scraped off by the cage 5. Therefore, even when the ball bearing 1 rotates at high speed, problems such as abnormal heat generation and wear at the contact points between the inner ring 2 and the balls 4 (inner raceway surface 2b) and the contact points between the outer ring 3 and the balls 4 (outer raceway surface 3b) are less likely to occur.

[0033] Furthermore, when the rotational speed of the ball bearing 1 in the second state falls below the predetermined value, the elastic expansion deformation of the outer ring 2 and the cage 5 due to frictional heat, etc., and the elastic expansion deformation of the cage 5 due to centrifugal force are suppressed, so the relationship between the size α of the pocket clearance Gb and the size β of the second radial clearance Ga2 as a guide clearance is reversed again. As a result, the system transitions to (returns to) the first state where the inequality α < β holds. In the cage 5 of this embodiment, the axial width of the guided portion 11 is smaller than the axial width of the base portion 10, and further smaller than the diameter of the hole 10a (cylindrical surface 7) provided in the base portion 10. This increases the ease of deformation of the guided portion 11, allowing for a smooth and appropriate transition between the first state and the second state during operation of the ball bearing 1, that is, a smooth and appropriate switching of the guidance mode of the cage 5.

[0034] Furthermore, in this embodiment, the ball bearing 1 can enjoy the above-mentioned effects because the outer ring 2 and the cage 5 elastically deform in accordance with the relative rotational speed of the inner ring 2 and the outer ring 3. Therefore, it can be realized more easily and at a lower cost compared to conventional ball bearings, which require meticulous control of the roundness of the guide surface of the raceway and the guided surface of the cage.

[0035] In summary, the ball bearing 1 of this embodiment can prevent, as much as possible, the occurrence of high-speed whirring of the cage 5, especially at low rotational speeds, and the resulting problems such as abnormal noise and vibration. Furthermore, it can reduce the frequency of contact between the cage 5 and the balls 4 at high rotational speeds, thereby suppressing abnormal heat generation and wear at the contact points between the inner ring 2 and outer ring 3 and the balls 4. Moreover, these effects can be easily and inexpensively achieved.

[0036] Let us give a specific example of a ball bearing 1 that can achieve the effects described above. For example, in a ball bearing 1 that uses an outer ring 3 with a design value of 95.4 mm for the diameter of its inner diameter surface 3a and a cage 5 with a design value of 95 mm for the diameter of its outer diameter surface 5b, the size β of the guide clearance (second radial clearance Ga2) when stopped is 0.4 mm. Also, when this ball bearing 1 is stopped, the size of the pocket circumferential clearance Gb1 is 0.365 mm and the size of the pocket radial clearance Gb2 is 0.34 mm. In this case, including when the ball bearing 1 is stopped, when the rotational speed of the ball bearing 1 is below a predetermined value, the size α of the pocket clearance Gb (pocket circumferential clearance Gb1 or pocket radial clearance Gb2) is smaller than the size β of the second radial clearance Ga2 (the inequality α < β holds), which is the first state.

[0037] Furthermore, if an outer ring 2 and cage 5 are used such that the decrease in the guide clearance (second radial clearance Ga2) due to the operation of the ball bearing 1 is 0.1 mm, the increase in the pocket circumferential clearance Gb1 is 0.03 mm, and the increase in the pocket radial clearance Gb2 is 0.06 mm, then the second state is reached where the size of the pocket clearance Gb (sizes of the pocket circumferential clearance Gb1 and pocket radial clearance Gb2) α is greater than the size of the second radial clearance Ga2 β = 0.3 mm (the inequality α > β holds).

[0038] Although a ball bearing 1 according to an embodiment of the present invention has been described above, the embodiments of the present invention are not limited thereto, and various modifications can be made without departing from the spirit of the invention. Below, a ball bearing 1 according to another embodiment of the present invention will be described, but only the changes from the ball bearing 1 described above will be explained in detail, and substantially identical components (members / parts) will be given the same reference numerals and redundant explanations will be omitted.

[0039] Figure 7 is a schematic longitudinal cross-sectional view of a ball bearing 1 according to a second embodiment of the present invention, Figure 8(a) is an overall perspective view of a cage 5 incorporated into the ball bearing 1 shown in Figure 7, and Figure 8(b) is a partially unfolded plan view of the cage 5 shown in Figure (a) as viewed from the radially outer side. As is particularly clear from Figures 8(a) and (b), in the ball bearing 1 according to this embodiment, the guided portion 11 constituting the cage 5 is formed in an annular shape, and the axial width of the guided portion 11 (maximum width portion) is greater than or equal to the hole diameter (diameter of the cylindrical surface 7) of the circular hole 10a provided in the base portion 10 of the cage 5. More specifically, the guided portion 11 in this embodiment has a shape that integrates an arc-shaped portion located between two adjacent pockets 6 and an annular portion located on one axial side of the arc-shaped portion, and the axial width of the guided portion 11 (maximum width portion) is greater than the hole diameter of the hole 10a and smaller than the axial width of the base portion 10.

[0040] With this configuration, when the cage 5 enters the second state where it acts as an outer ring guide, the contact area of ​​the cage 5 with respect to the inner diameter surface 3a of the outer ring 3, which functions as the guide surface of the cage 5, can be increased compared to the ball bearing 1 (cage 5) of the first embodiment described with reference to Figure 1, etc. Therefore, the guidance accuracy of the cage 5 can be improved, and the behavior of the cage 5 during bearing operation can be stabilized.

[0041] Figure 9 is a schematic longitudinal cross-sectional view of a ball bearing 1 according to the third embodiment of the present invention, Figure 10(a) is an overall perspective view of the cage 5 incorporated in the ball bearing 1 shown in Figure 9, and Figure 9(b) is a partially unfolded plan view of the cage 5 shown in Figure 9(a) as viewed from the radially outer side. In particular, as is clear from Figures 10(a) and (b), in the ball bearing 1 according to this embodiment, the axial width of the guided portion 11 of the cage 5 is increased compared to the cage 5 of the second embodiment shown in Figures 8(a) and (b), and is made the same width as the base portion 10. Therefore, the axial width of the guided portion 11 (at its widest point) is larger than the hole diameter (diameter of the cylindrical surface 7) of the hole portion 10a. With this configuration, when the guide type of the cage 5 is in the second state of outer ring guidance, the contact area of ​​the cage 5 with the inner diameter surface 3a of the outer ring 3, which functions as the guide surface of the cage 5, can be further increased. Therefore, the guidance accuracy of the cage 5 during bearing operation can be improved, and the behavior of the cage 5 can be stabilized.

[0042] If the axial width of the guided portion 11 (maximum width portion) of the retainer 5 is made larger than the hole diameter of the hole 10a, then, for example, as shown in Figure 11, a plurality of axial grooves 12 may be provided on the outer diameter surface of the retainer 5 at intervals in the circumferential direction, and the plurality of guided portions 11 may be arranged at intervals in the circumferential direction by these plurality of axial grooves 12. In this way, the deformability of the retainer 5 can be increased compared to the retainer 5 shown in Figure 10.

[0043] As explained above, the present invention makes it possible to prevent the occurrence of high-speed whirring in the cage 5 that constitutes the ball bearing 1, and therefore can be particularly preferably applied to ball bearings used in applications where high-speed whirring is likely to occur. For example, in the case of ball bearings that support the spindles of machine tools or reaction wheels of aerospace equipment, these ball bearings are subjected to relatively large axial preloads during use. Specifically, the ratio of the radial load Fr to the axial load Fa (=Fr / Fa) received during operation is often 3 or less, and in such cases, high-speed whirring is particularly likely to occur. This is because the higher the ball spacing, the more likely high-speed whirring is to occur. Conversely, when the radial load acting on the ball bearing is significantly larger than the axial load (for example, when the above ratio Fr / Fa exceeds 3), a delay occurs in each ball, resulting in uneven spacing between the balls, making high-speed whirring less likely to occur. Therefore, the present invention can be particularly suitably applied to ball bearings used in applications where the relationship Fr / Fa ≤ 3.0 holds true, such as the spindles of machine tools and the support bearings of reaction wheels in aerospace equipment.

[0044] Although the ball bearing 1 according to the present invention has been described above, the present invention is not limited in any way to the embodiments described above, and can be implemented in various other forms without departing from the spirit of the present invention. [Explanation of Symbols]

[0045] 1 ball bearing 2 Inner ring 3 Outer ring 3a Inner surface 4 balls 5 Cage 6 pockets 7. Cylindrical surface 8 Slope 10 base 11 Guided part 12 Axial groove F Frictional force Ga1 First radial clearance Ga2 Second radial clearance (guide clearance) Gb Pocket Gap Gb1 Pocket circumferential clearance Gb2 pocket radial clearance

Claims

1. A ball bearing comprising an inner ring and an outer ring that rotate relative to each other via a plurality of balls, an annular cage that individually holds the balls, and a lubricant interposed in the annular space between the inner ring and the outer ring, The ball is housed in a pocket defined by a cylindrical surface formed in the retainer. When the relative rotational speed of the inner ring and the outer ring is less than or equal to a predetermined value, the outer ring and the retainer elastically deform in accordance with the relative rotational speed of the inner ring and the outer ring, such that the relationship between the size α of the pocket gap formed between the ball and the retainer and the size β of the guide gap formed between the inner diameter surface of the outer ring and the outer diameter surface of the retainer is α < β, and when the relative rotational speed exceeds the predetermined value, the relationship is α > β, thus the outer ring and the retainer elastically deform in accordance with the relative rotational speed of the inner ring and the outer ring. The ball bearing is characterized in that the cage has an inclined portion that is inclined in a direction that gradually reduces the diameter of the cylindrical surface toward the radially outward direction, and this inclined portion is provided continuously on the outer diameter side of the cylindrical surface.

2. The ball bearing according to claim 1, wherein the cage integrally comprises an annular base having a plurality of cylindrical surfaces spaced apart in the circumferential direction, and a guided portion located radially outward from the base, the outer diameter surface of which in the second state is guided by the inner diameter surface of the outer ring, and the inclined portion is provided on the guided portion.

3. The ball bearing according to claim 2, wherein the guided portion is arranged between two adjacent cylindrical surfaces in the circumferential direction, and its axial width is smaller than the diameter of the cylindrical surface.

4. The ball bearing according to claim 2, wherein the axial width of the guided portion is greater than or equal to the diameter of the cylindrical surface.

5. The ball bearing according to claim 4, wherein a plurality of axial grooves are provided on the outer diameter surface of the cage at intervals in the circumferential direction, and a plurality of guided portions are arranged at intervals in the circumferential direction by the plurality of axial grooves.

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