Inner ring separate-type angular ball bearing

Abstract

To provide an inner ring separate-type angular ball bearing which hardly causes a scratch on a surface of a ball and inner / outer ring raceway grooves by smoothly inserting an inner ring into an outer ring.SOLUTION: A point between a ball 3 and an outer ring shoulder part 6 when the ball 3 of an outer ring assembly falls to the inside of a radial direction by its own weight is set as a contact point X, and a point at which a center line passing a center O of the ball 3 intersects with a surface of the ball 3 is set as a cross point Y. A rotation angle β around the center O of the ball 3 in a direction into which the ball 3 falls rather than the cross point Y is set as a positive angle, and a rotation angle in a reverse direction is set as a negative angle. An abutment point Z at which the ball 3 and an inner ring counterbore part 9 firstly abut on each other when inserting an inner ring 2 downward is located at a positive side rather than the cross point Y. A relationship of 1.00<C / D≤2.50 is established between a magnitude C of a ball circumscription-side clearance being a clearance between a circumscription circle diameter Ro of the ball 3 and a groove bottom of an outer ring raceway groove 5, and a magnitude D of a ball inscription-side superimposition being a difference between an inscription circle diameter Ri of the ball 3 when inserting the inner ring 2 downward from the inner ring counterbore part 9 side, and an outside diameter Rc of the inner ring counterbore part 9.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This invention relates to a separated inner ring angular contact ball bearing configured to allow the inner ring to be smoothly inserted into a structure that integrally holds an outer ring, a cage, and rolling elements. [Background technology]

[0002] Traditionally, tapered roller bearings with tapered bearings have been widely used in automotive automatic transmissions because they are subject to not only high radial loads but also axial loads. However, in recent years, the need for fuel-efficient automobiles has led to an increase in the use of angular contact ball bearings as transmission bearings. Angular contact ball bearings can withstand both radial and axial loads and have lower torque than tapered roller bearings.

[0003] When angular contact ball bearings are used in transmissions, separable angular contact ball bearings are generally used to ensure ease of assembly and disassembly of the transmission.Separable angular contact ball bearings are angular contact ball bearings that are designed so that the balls do not fall out of the cage pockets even when the inner or outer ring is separated.

[0004] A known example of a split-type angular contact ball bearing is the split-inner-ring angular contact ball bearing described in Patent Document 1. The split-inner-ring angular contact ball bearing of Patent Document 1 includes an outer ring, an inner ring arranged coaxially radially inside the outer ring, a plurality of balls assembled between the outer ring and the inner ring at intervals in the circumferential direction, and a cage that holds the plurality of balls.

[0005] The inner circumference of the outer ring is provided with an outer ring raceway groove with which the balls roll, an outer ring counterbore adjacent to one axial side of the outer ring raceway groove, and an outer ring shoulder adjacent to the other axial side of the outer ring raceway groove.The outer circumference of the inner ring is provided with an inner ring raceway groove with which the balls roll, an inner ring counterbore adjacent to one axial side of the inner ring raceway groove, and an inner ring shoulder adjacent to the other axial side of the inner ring raceway groove.The outer ring counterbore is a portion shaped by removing part or all of the outer ring raceway groove, and the inner ring counterbore is a portion shaped by removing part or all of the groove shoulder of the inner ring raceway groove. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-95929 Summary of the Invention [Problem to be solved by the invention]

[0007] In the separated inner ring angular contact ball bearing of Patent Document 1, as shown in Figure 13, for example, when inserting an inner ring 54 into a retainer (hereinafter referred to as the outer ring assembly) that integrally holds an outer ring 51, a retainer 52, and balls 53 fitted into a housing bore 50, the balls 53, which have fallen radially inward due to their own weight, are pulled further downward by the inner ring 54, which is inserted downward, causing the outer ring 51, balls 53, and retainer 52 to separate, or the balls 53 to become caught between the outer ring 51 and the inner ring 54 as the inner ring 54 is inserted, making it impossible to insert the inner ring 54 smoothly and risking damage to the surfaces of the balls 53 and the inner and outer ring raceway grooves.

[0008] The problem to be solved by this invention is to provide an angular contact ball bearing with a separated inner ring, in which the inner ring can be smoothly inserted into the outer ring assembly, and the surfaces of the balls and the inner and outer ring raceway grooves are less likely to be damaged. be. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides an inner-ring separable angular ball bearing having the following configuration. An outer ring, An inner ring coaxially disposed radially inward of the outer ring, A plurality of balls incorporated with a circumferential interval between the outer ring and the inner ring, A cage for holding the plurality of balls, and On the inner circumference of the outer ring, there are provided an outer-ring raceway groove with which the balls rollingly contact, an outer-ring shoulder adjacent to one axial side of the outer-ring raceway groove, and an outer-ring counterbore portion adjacent to the other axial side of the outer-ring raceway groove and having an inner diameter larger than that of the outer-ring shoulder, On the outer circumference of the inner ring, there are provided an inner-ring raceway groove with which the balls rollingly contact, an inner-ring counterbore portion adjacent to one axial side of the inner-ring raceway groove, and an inner-ring shoulder adjacent to the other axial side of the inner-ring raceway groove and having an outer diameter larger than that of the inner-ring counterbore portion, In the inner-ring separable angular ball bearing in which when the inner ring is separated, the balls are supported so as not to drop radially inward from the pockets formed in the cage, With the outer ring, the cage, and the balls held integrally, when the ball drops radially inward due to its own weight, the contact point between the ball and the outer-ring shoulder and the center line passing through the center of the ball intersect the surface of the ball at an intersection point. When the rotation angle around the center of the ball in the direction in which the ball drops is defined as positive and the rotation angle in the reverse direction from the intersection point is defined as negative, when the inner ring is inserted downward from the inner-ring counterbore portion side, the contact point where the ball and the inner-ring counterbore portion first come into contact is on the positive side of the intersection point, There is a relationship of 1.00 < C / D ≤ 2.50 between the size C of the ball outer circumscribed side clearance, which is the radial clearance between the outer diameter of the circumscribed circle of the ball when the ball drops radially inward due to its own weight and the groove bottom of the outer-ring raceway groove, and the size D of the ball inner circumscribed side overlap, which is the difference between the inner diameter of the inscribed circle of the ball when the inner ring is inserted downward from the inner-ring counterbore portion side and the outer diameter of the inner-ring counterbore portion. The inner-ring separable angular ball bearing is characterized by this.

[0010] In this way, by making the contact point on the positive side of the intersection, when the inner ring is inserted downward into the outer ring assembly, the balls are not pulled downward by the inner ring counterbore portion of the inner ring, so the assembly can be done smoothly.

[0011] Furthermore, by setting the relationship between the ball circumferential clearance C and the ball inscribed-side overlap D within the above range, the balls are pushed back along the outer ring raceway groove as the inner ring is inserted, allowing for smooth insertion. If the ball inscribed-side overlap D is larger than the ball circumferential clearance C, interference occurs between the balls and the inner ring during insertion, applying pressure to the balls and potentially damaging or cracking the balls. Furthermore, if the value obtained by dividing the ball circumferential clearance C by the ball inscribed-side overlap D is greater than 2.50, the gap between the balls and the inner and outer ring raceway grooves becomes too large, potentially resulting in an inconsistent contact angle or the balls riding up against the shoulders of the inner and outer rings. For this reason, it is necessary to set the relationship between the ball circumferential clearance C and the ball inscribed-side overlap D within the above range.

[0012] It is preferable that a tapered surface be formed on the outer diameter surface of the inner ring counterbore portion, with an axial inclination angle α satisfying 0°<α≦30° and with an outer diameter that gradually decreases with increasing distance from the inner ring raceway groove.

[0013] In this way, the contact pressure can be reduced compared to when the balls come into direct contact with the chamfered portion of the inner ring counterbore, making the ball surface less likely to be scratched. Also, by forming a tapered surface, the length of the counter flat portion that needs to be ground (see Lc in Figure 4) is reduced. This shortens the cycle time during manufacturing. Note that if the inclination angle α is greater than 30 degrees, it becomes difficult to ensure the length of the width flat portion of the inner ring required for machining (see Lw in Figure 4), so it is preferable to keep it in the above range.

[0014] It is preferable that a solid lubricating coating is formed on the outer diameter surface of the inner race counterbore portion.

[0015] By doing so, the friction between the ball and the outer diameter surface of the inner ring counter bore portion is reduced, so that the inner ring can be smoothly inserted without damaging the surface of the ball.

[0016] The above inner ring separable angular ball bearing is particularly suitable for use as a bearing for an automobile transmission.

Advantages of the Invention

[0017] In the inner ring separable angular ball bearing of this invention, in a state where the balls of the outer ring assembly have fallen, the contact point between the ball and the inner ring counter bore portion is made positive with respect to the intersection defined on the surface of the ball, and between the size C of the clearance on the outer circumscribed side of the ball and the size D of the overlap on the inner circumscribed side of the ball, a relationship of 1.00 < C / D ≦ 2.50 is established. As a result, when the inner ring is inserted downward into the outer ring assembly, the balls are not pulled downward by the inner ring counter bore portion of this inner ring, so that the insertion can be performed smoothly. Moreover, by setting the magnitude relationship between the size C of the clearance on the outer circumscribed side of the ball and the size D of the overlap on the inner circumscribed side of the ball within the above range, the balls are not bitten between the outer ring and the inner ring as the inner ring is inserted, and the surface of the balls and the inner and outer ring raceway grooves are not easily damaged.

Brief Description of the Drawings

[0018] [Figure 1] Cross-sectional view showing an embodiment of the inner ring separable angular ball bearing according to this invention [Figure 2] Cross-sectional view showing the main part of FIG. 1 [Figure 3] Diagram showing the dimensional relationship of each member in FIG. 2 [Figure 4] Cross-sectional view of the inner ring of the inner ring separable angular ball bearing shown in FIG. 1 [Figure 5] Cross-sectional view showing a state where one outer ring assembly of the inner ring separable angular ball bearing shown in FIG. 1 is attached to a housing hole [Figure 6] Cross-sectional view showing a state where one more outer ring assembly is attached to the housing hole following FIG. 5 [Figure 7]Following on from Figure 6, this is a cross-sectional view showing the state in which a shaft body with one inner ring is inserted. [Figure 8] A cross-sectional view showing the state after inserting another inner ring, following Figure 7. [Figure 9] Cross-sectional view showing the contact force acting on the ball when the inner ring is inserted [Figure 10] FIG. 2 is a cross-sectional view showing a main part of a modified example of the separated inner ring angular contact ball bearing shown in FIG. 1. [Figure 11] Cross-sectional view showing the first example of application of the separated inner ring angular contact ball bearing shown in Figure 1 to an automobile transmission [Figure 12] Cross-sectional view showing a second example of application of the separated inner ring angular contact ball bearing shown in Figure 1 to an automobile transmission [Figure 13] 1 is a cross-sectional view of a main part showing an inner ring insertion process in a conventional separated inner ring angular contact ball bearing. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of a separated inner ring angular contact ball bearing A according to the present invention will be described below with reference to the drawings. The separated inner ring angular contact ball bearing A shown in Fig. 1 has an outer ring 1, an inner ring 2 arranged coaxially on the radially inner side of the outer ring 1, a plurality of balls 3 (steel balls) assembled at intervals in the circumferential direction between the outer ring 1 and the inner ring 2, and a cage 4 that holds the plurality of balls 3.

[0020] The inner circumference of the outer ring 1 is provided with an outer ring raceway groove 5 with which the balls 3 roll and make contact, an outer ring shoulder 6 adjacent to one axial side (left side in FIG. 1) of the outer ring raceway groove 5, and an outer ring shoulder 6 adjacent to the other axial side (left side in FIG. 1) of the outer ring raceway groove 5. The outer ring raceway groove 5 is a groove with an arc-shaped cross section that extends circumferentially around the inner circumference of the outer ring 1. The outer ring 1 is made of bearing steel. The outer ring counterbore 7 is a portion shaped by removing part or all of the groove shoulder of the outer ring raceway groove 5. The inner diameter of the outer ring counterbore 7 is larger than the inner diameter of the outer ring shoulder 6.

[0021] The outer periphery of the inner ring 2 is provided with an inner ring raceway groove 8 with which the balls 3 roll, an inner ring counterbore 9 adjacent to one axial side (the left side in Figure 1) of the inner ring raceway groove 8, and an inner ring shoulder 10 adjacent to the other axial side of the inner ring raceway groove 8. The inner ring raceway groove 8 is a groove with an arc-shaped cross section that extends circumferentially around the outer periphery of the inner ring 2. The inner ring 2 is made of bearing steel. The inner ring counterbore 9 is a portion shaped like the inner ring raceway groove 8 with part or all of the groove shoulder removed. The outer diameter of the inner ring shoulder 10 is larger than the outer diameter of the inner ring counterbore 9.

[0022] As shown in Figures 3 and 4, the outer peripheral surface of the inner ring counterbore portion 9 forms a tapered surface 11 whose outer diameter gradually decreases with increasing distance from the inner ring raceway groove 8. The axial inclination angle α of this tapered surface 11 is greater than 0 degrees and not greater than 30 degrees. A counter flat portion (range Lc in Figure 4) that is flat in the axial direction is formed between the inner ring raceway groove 8 and the tapered surface 11. In addition, a flat width flat portion (range Lw in Figure 4) is formed on the axial end face of the inner ring counterbore portion 9.

[0023] A solid lubricating coating is formed on the outer peripheral surface of the inner ring counterbore portion 9. This solid lubricating coating reduces friction with the balls 3 when the inner ring 2 is inserted, preventing damage to the surface of the balls 3 during insertion. Forming a solid lubricating coating on the tapered surface 11 in particular allows for smoother insertion of the inner ring 2. Materials such as black oxide and diamond-like carbon (DLC) can be used for this solid lubricating coating. Black oxide is a porous black oxide coating that provides lubricity by retaining lubricating oil or the like within its pores. DLC is a low-friction coating with properties intermediate between those of diamond and graphite, providing lubrication. Molybdenum-based and fluorine-based solid lubricating coatings can also be used. Note that this solid lubricating coating is not a required component and may be omitted in some cases.

[0024] The cage 4 has a counter-side annular portion 12 extending circumferentially on one axial side (left side in FIG. 1 ) of the balls 3, an anti-counter-side annular portion 13 extending circumferentially on the other axial side (right side in FIG. 1 ) of the balls 3, and multiple pillars 14 passing between adjacent balls 3 in the circumferential direction and connecting the counter-side annular portion 12 and the anti-counter-side annular portion 13. The counter-side annular portion 12, the anti-counter-side annular portion 13, and the pillars 14 define pockets 15 that accommodate the balls 3. When the inner ring 2 is separated, the balls 3 are supported by the pockets 15 to prevent them from falling radially inward. The counter-side annular portion 12 and the anti-counter-side annular portion 13 fit around the balls 3, thereby positioning the cage 4. At this time, neither the counter-side annular portion 12 nor the anti-counter-side annular portion 13 contacts the outer ring 1 or the inner ring 2.

[0025] Resin is used as the material of the cage 4. As this resin, polyamides such as PA46 (polyamide 46), PA66 (polyamide 66), and PA9T (polynonamethylene terephthalamide), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), and the like can be used.

[0026] As shown in Figure 2, in a retainer (hereinafter referred to as outer ring assembly) that integrally holds the outer ring 1, cage 4, and balls 3, the balls 3 drop slightly radially inward due to their own weight. At this time, the point where the center line passing through the contact point X between the balls 3 and the outer ring shoulder 6 and the center O of the balls intersects with the surface of the balls 3 is defined as the intersection point Y. The rotation angle β of the balls 3 around the center O in the direction in which the balls 3 drop from this intersection point Y is defined as positive, and the rotation angle β in the opposite direction from the intersection point Y is defined as negative. When the inner ring 2 is inserted into the outer ring assembly, its inner ring counterbore portion 9 first abuts against the balls 3 at abutment point Z. If this abutment point Z is on the positive rotation angle β side of the intersection point Y, as will be described later (see Figure 9), the abutment force with the inner ring 2 can smoothly push back the balls 3, which have fallen under their own weight, along the outer ring raceway groove 5.

[0027] In addition, in the outer ring assembly, when the ball 3 drops radially inward due to its own weight, the size C of the ball outer contact side clearance, which is the radial clearance between the outer diameter Ro of the circumscribed circle of the ball 3 and the groove bottom of the outer ring raceway groove 5, and the size D of the ball inner contact side overlap, which is the difference between the inner diameter Ri of the inscribed circle of the ball 3 and the outer diameter Rc of the inner ring counter bore portion 9 when the inner ring 2 is inserted downward from the inner ring counter bore portion 9 side, satisfy the relationship 1.00 < C / D ≤ 2.50. Therefore, when the ball 3 that has dropped due to its own weight is pushed back along the outer ring raceway groove 5 by the contact force with the inner ring 2 (inner ring counter bore portion 9), no pressure is applied to the ball 3 and no scratches or cracks occur. Moreover, the gap between the ball 3 and the inner and outer ring raceway grooves 5 and 8 does not become large, and the ball 3 does not ride up on the inner and outer ring shoulders 6 and 10, nor does the contact angle deviate from the assumed value.

[0028] An example of the operation of assembling the first angular ball bearing A and the second angular ball bearing B to an object will be described. In the following description, members with the prefix "first" are components of the first angular ball bearing A, and members with the prefix "second" are components of the second angular ball bearing B.

[0029] First, as shown in FIG. 5, a second outer ring assembly B' (which integrally holds the outer ring 1, a plurality of balls 3, and the cage 4) is fitted into a housing hole 16 provided in the object. At this time, the second outer ring assembly B' is inserted into the housing hole 16 with the counter-side annular portion 13 of the cage 4 on the upper side and the counter-side annular portion 12 on the lower side. Also, the outer ring 1 of the second outer ring assembly B' is fitted with an interference fit to the inner circumference of the housing hole 16.

[0030] Next, as shown in Figure 6, a retaining ring 18 is fitted into a retaining ring groove 17 formed on the inner periphery of the housing bore 16. This retaining ring 18 fixes the position of the outer ring 1 of the second outer ring assembly B'. After that, the first outer ring assembly A' is fitted into the housing bore 16 in a position below the second outer ring assembly B'. At this time, the first outer ring assembly A' is inserted into the housing bore 16 with the counter-side annular portion 12 of the cage 4 facing up and the anti-counter-side annular portion 13 facing down. The outer ring 1 of the first outer ring assembly A' is fitted into the inner periphery of the housing bore 16 with interference.

[0031] Meanwhile, as shown in Figure 7, the first inner ring 2 is mounted on the outer periphery of the shaft 19. At this time, the first inner ring 2 is mounted on the outer periphery of the shaft with the inner ring counterbore portion 9 on the upper side and the inner ring shoulder portion 10 on the lower side. The first inner ring 2 is fitted onto the outer periphery of the shaft 19 with an interference fit. After that, the first outer ring assembly A' is mounted on the outer periphery of the first inner ring 2 from above. With this mounting, the first angular contact ball bearing A is completed. In this embodiment, the outer diameter Rt of the tip of the inner ring counterbore portion 9 of the inner ring 2 is designed to be smaller than the inscribed circle diameter Ri of the balls 3, so the first outer ring assembly A' can be mounted smoothly on the outer periphery of the first inner ring 2.

[0032] Thereafter, as shown in Figure 8, the second inner ring 2 is inserted into the second outer ring assembly B' from above, with the inner ring counterbore 9 facing downward and the inner ring shoulder 10 facing upward. At this time, the second inner ring 2 is fitted onto the outer periphery of the shaft 19 with interference. This completes the second angular contact ball bearing B.

[0033] In this manner, the first angular contact ball bearing A and the second angular contact ball bearing B can be assembled to the object.

[0034] When inserting the inner ring 2 in Fig. 8, a contact force toward the center O of the ball is generated at the contact point Z between the ball 3 and the inner ring 2 (inner ring counterbore portion 9) as shown in Fig. 9. This contact force has a horizontal component F that pushes the ball 3 back toward the outer ring raceway groove 5. Hand the vertical component F that pulls the ball 3 downward along the insertion direction of the inner ring 2 V can be decomposed. When this contact point Z is at a positive position of the rotation angle β with respect to the intersection point Y (the direction position where the ball 3 falls), the vertical component F V has a horizontal component F H which becomes large, and the ball 3 can be smoothly pushed back toward the outer ring raceway groove 5.

[0035] On the contrary, as shown in FIG. 13, when the contact point Z is at a negative position of the rotation angle β with respect to the intersection point Y (the direction position opposite to the direction where the ball 3 falls), the horizontal component F H ’ and the vertical component F V ’ are of the same magnitude, or the vertical component F H ’ is larger than the horizontal component F V ’, and there is a risk that the ball 3 may be pulled in the insertion direction as the inner ring 2 is inserted, or the inner ring 2 may not be inserted smoothly.

[0036] The main part of a modified example of the inner ring separable angular ball bearing A shown in FIG. 1 is shown in FIG. 10. This modified example is different from the above-described configuration only in that the tapered surface 11 is not formed on the inner ring counter bore portion 9. When inserting the inner ring 2 with respect to the outer ring assembly, the contact point Z where the ball 3 of this outer ring assembly and the inner ring 2 (inner ring counter bore portion 9) first come into contact is on the positive rotation angle β side with respect to the intersection point Y, and there is a common point that the relationship 1.00 < C / D ≤ 2.50 holds between the size C of the ball outer contact side gap and the size D of the ball inner contact side overlap. Therefore, also in this modified example, as in the above, as the inner ring 2 is inserted, the ball 3 can be smoothly pushed back toward the outer ring raceway groove 5, and along with this pushing back, it is possible to prevent pressure from being applied to the ball 3 and causing scratches or cracks, or the ball 3 from riding on the inner and outer ring shoulders 6 and 10 without achieving the assumed contact angle.

[0037] As shown in FIGS. 11 and 12, the above-described inner ring separable angular ball bearing A can be used as a bearing for an automobile transmission.

[0038] The transmission shown in Figure 11 is a full-synchromesh transmission, which is a constantly meshing gear mechanism. In this transmission, gear 30 on the input shaft side and gear 32 on the output shaft 31 side mesh with each other. Shaft 33, which is rotated by the input shaft and output shaft 31, is rotatably supported by a separated inner ring angular contact ball bearing A. This separated inner ring angular contact ball bearing A not only receives the radial load from the input shaft or output shaft 31, but also the axial load, which is the axial component of the force.

[0039] The transmission shown in Figure 12 is a continuously variable transmission that changes the rotational speed of an automobile engine and outputs the rotation, allowing for continuously variable gear ratios. This transmission includes a torque converter 35 connected to a crankshaft 34 of the automobile engine, an input shaft 36 to which the rotation of the automobile engine is input via the torque converter 35, an output shaft 37 disposed parallel to the input shaft 36, a drive V-groove pulley 38 disposed on the outer periphery of the input shaft 36 so as to rotate integrally with the input shaft 36, a driven V-groove pulley 39 disposed on the outer periphery of the output shaft 37 so as to rotate integrally with the output shaft 37, and a V-belt 40 wound between the drive V-groove pulley 38 and the driven V-groove pulley 39. The input shaft 36 and the output shaft 37 are rotatably supported by a separated inner ring angular contact ball bearing A. The separated inner ring angular contact ball bearing A receives not only a radial load from the input shaft 36 or the output shaft 37 but also an axial load, which is an axial component of the force.

[0040] The embodiments disclosed herein are illustrative in all respects and are not to be considered as limiting. The scope of the present invention is defined by the claims, rather than the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0041] 1 outer ring 2. Inner circle 3 balls 4 Cage 5 Outer ring raceway groove 6 Outer ring shoulder 7 Outer ring counterbore 8 Inner ring raceway groove 9 Inner ring counterbore 10 Inner ring shoulder 11 Tapered surface 15 pockets A Separated inner ring angular contact ball bearing O center X contact point Y-intersection Z contact point α Tilt angle β rotation angle

Claims

1. The outer ring (1) and an inner ring (2) arranged coaxially on the radially inner side of the outer ring (1); a plurality of balls (3) assembled at intervals in the circumferential direction between the outer ring (1) and the inner ring (2); a cage (4) for holding the plurality of balls (3), The inner periphery of the outer ring (1) is provided with an outer ring raceway groove (5) with which the balls (3) roll and make contact, an outer ring shoulder portion (6) adjacent to one side of the outer ring raceway groove (5) in the axial direction, and an outer ring counterbore portion (7) adjacent to the other side of the outer ring raceway groove (5) in the axial direction and having an inner diameter larger than that of the outer ring shoulder portion (6), The inner ring (2) is provided on its outer periphery with an inner ring raceway groove (8) with which the balls (3) roll, an inner ring counterbore portion (9) adjacent to one side of the inner ring raceway groove (8) in the axial direction, and an inner ring shoulder portion (10) adjacent to the other side of the inner ring raceway groove (8) in the axial direction and having an outer diameter larger than that of the inner ring counterbore portion (9), In a separated inner ring angular contact ball bearing, the balls (3) are supported so as not to fall out radially inward from pockets (15) formed in the cage (4) when the inner ring (2) is separated, When the outer ring (1), the cage (4), and the balls (3) are held integrally, and the balls (3) drop radially inward due to their own weight, the point at which a center line passing through the contact point (X) between the balls (3) and the outer ring shoulder (6) and the center (O) of the balls (3) intersects with the surface of the balls (3) is defined as an intersection point (Y), and a rotation angle (β) about the center (O) of the balls (3) in the direction in which the balls (3) drop from the intersection point (Y) is defined as positive, and a rotation angle (β) in the opposite direction from the intersection point (Y) is defined as negative, the abutment point (Z) where the balls (3) and the inner ring counterbore portion (9) first come into contact when the inner ring (2) is inserted downward from the inner ring counterbore portion (9) side is located on the positive side of the intersection point (Y), When the inner ring (2) abuts on the positive rotation angle (β) side of the intersection point (Y), the balls (3) that have fallen under their own weight are pushed back along the outer ring raceway groove (5), A tapered surface (11) is formed on the outer peripheral surface of the inner ring counterbore portion (9), the outer diameter of which gradually decreases as it moves away from the inner ring raceway groove (8), A counter flat portion that is flat in the axial direction is formed between the inner ring raceway groove (8) and the tapered surface (11), and the counter flat portion is continuous with the groove bottom of the inner ring raceway groove (8).

2. 2. The separated inner ring angular contact ball bearing according to claim 1, wherein the inclination angle α of the tapered surface (11) in the axial direction satisfies 0°<α≦30°.

3. 3. The separated inner ring angular contact ball bearing according to claim 1, which is used as a bearing for an automobile transmission.

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