Inner ring separable angular contact 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] The present invention relates to an inner ring separable angular ball bearing configured to be able to smoothly insert an inner ring when inserting the inner ring into a unit that integrally holds an outer ring, a cage, and rolling elements.

Background Art

[0002] Conventionally, bearings used in automotive automatic transmissions are subject to not only high radial loads but also axial loads, so tapered roller bearings have been widely used. However, in recent years, due to the need for fuel efficiency improvement in automobiles, the use of angular ball bearings as transmission bearings has been increasing. Angular ball bearings can bear both radial and axial loads and have lower torque than tapered roller bearings.

[0003] When an angular ball bearing is used in a transmission, a separable angular ball bearing is generally adopted to ensure the workability of assembling and disassembling the transmission. A separable angular ball bearing is an angular ball bearing configured such that the balls do not fall out of the pockets of the cage even when the inner ring or the outer ring is separated.

[0004] As a separable angular ball bearing, for example, the inner ring separable angular ball bearing of Patent Document 1 below is known. The inner ring separable angular ball bearing of Patent Document 1 includes an outer ring, an inner ring coaxially arranged radially inside the outer ring, a plurality of balls incorporated with a circumferential interval between the outer ring and the inner ring, and a cage that holds the plurality of balls.

[0005] On the inner circumference of the outer ring, there are provided an outer ring raceway groove with which balls roll and come into contact, an outer ring counterbore portion adjacent to one axial side of the outer ring raceway groove, and an outer ring shoulder portion adjacent to the other axial side of the outer ring raceway groove. Also, on the outer circumference of the inner ring, there are provided an inner ring raceway groove with which balls roll and come into contact, an inner ring counterbore portion adjacent to one axial side of the inner ring raceway groove, and an inner ring shoulder portion adjacent to the other axial side of the inner ring raceway groove. The outer ring counterbore portion is a portion having a shape in which part or all of the outer ring raceway groove is removed, and the inner ring counterbore portion is a portion having a shape in which part or all of the groove shoulder of the inner ring raceway groove is removed, respectively.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the inner ring separable angular ball bearing according to Patent Document 1, for example, as shown in FIG. 13, when inserting the inner ring 54 into a holding body (hereinafter referred to as an outer ring assembly) that integrally holds the outer ring 51, the cage 52, and the balls 53 fitted into the housing hole 50, the balls 53 that have fallen radially inward due to their own weight are further drawn downward by the inner ring 54 inserted downward, and the outer ring 51, the balls 53, and the cage 52 are separated, or the balls 53 are caught between the outer ring 51 and the inner ring 54 as the inner ring 54 is inserted, making it impossible to smoothly insert the inner ring 54 and there is a risk of damaging the surface 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 inner ring separable angular ball bearing that can smoothly insert the inner ring into the outer ring assembly and is less likely to damage the surface of the balls and the inner and outer ring raceway grooves.

Means for Solving the Problems

[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 inside 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, 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 radially drop inward from the pockets formed in the cage, With the outer ring, the cage, and the balls integrally held, 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 positive and the rotation angle in the reverse direction from the intersection point is 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, The inner ring separable angular ball bearing is characterized in that a relationship of 1.00 < C / D ≦ 2.50 is established between the size C of the ball outer circumscribed side clearance, which is the radial clearance between the outer circumscribed diameter 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 circumscribed diameter 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.

[0010] By doing so, since the contact point is set to the positive side of the intersection, when the inner ring is inserted downward into the outer ring assembly, the balls are not drawn downward by the inner ring counterbore portion of this inner ring, so that the incorporation can be performed smoothly.

[0011] Also, by setting the magnitude relationship between the size C of the ball outer circumferential side gap and the size D of the ball inner circumferential side overlap within the above range, as the inner ring is inserted, the balls are pushed back along the outer ring raceway groove, so that the insertion can be performed smoothly. If the size D of the ball inner circumferential side overlap is larger than the size C of the ball outer circumferential side gap, a tightening allowance occurs between the balls during the insertion of the inner ring and pressure is applied to the balls, so there is a risk of damage or cracking to these balls. Further, if the value obtained by dividing the size C of the ball outer circumferential side gap by the size D of the ball inner circumferential side overlap is larger than 2.50, the gap between the balls and the inner and outer ring raceway grooves becomes large, and there is a risk that the assumed contact angle will not be achieved or that the balls will ride up on the inner and outer ring shoulders. For this reason, it is necessary to set the magnitude relationship between the size C of the ball outer circumferential side gap and the size D of the ball inner circumferential side overlap within the above range.

[0012] It is preferable that a tapered surface is formed on the outer diameter surface side of the inner ring counterbore portion, satisfying 0° < α ≦ 30° for the axial inclination angle α and gradually decreasing in outer diameter as it moves away from the inner ring raceway groove.

[0013] By doing so, the contact surface pressure can be reduced compared to the case where the balls come into direct contact with the chamfered portion of the inner ring counterbore portion, so that the surface of the balls is less likely to be damaged. Also, by forming the tapered surface, the length of the counter flat portion (refer to Lc in FIG. 4) that requires grinding becomes shorter, so that the cycle time during manufacturing can be shortened. Note that if this inclination angle α is larger than 30 degrees, it becomes difficult to ensure the length of the width flat portion of the inner ring (refer to Lw in FIG. 4) required for processing, so it is preferable to be within the above range.

[0014] It is preferable that a solid lubricant film is formed on the outer diameter surface side of the inner ring counterbore portion.

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

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

Effect of the Invention

[0017] In the inner ring separable angular ball bearing of this invention, with the balls of the outer ring assembly in a dropped state, the contact point between the ball and the inner ring counterbore portion is made to be on the positive side rather than the intersection defined on the surface of the ball, and a relationship of 1.00 < C / D ≤ 2.50 is established between the size C of the ball outer circumferential side gap and the size D of the ball inner circumferential side overlap. As a result, when the inner ring is inserted downward into the outer ring assembly, the balls are not drawn downward by the inner ring counterbore 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 ball outer circumferential side gap and the size D of the ball inner circumferential side overlap within the above range, the balls are not caught 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

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, with reference to the drawings, an embodiment of the inner-ring separable angular ball bearing A according to the present invention will be described. The inner-ring separable angular ball bearing A shown in FIG. 1 includes an outer ring 1, an inner ring 2 coaxially disposed radially inward of the outer ring 1, a plurality of balls 3 (steel balls) incorporated 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] On the inner circumference of the outer ring 1, there are provided an outer-ring raceway groove 5 in which the balls 3 rollingly 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 counterbore portion 7 adjacent to the other axial side (right side in FIG. 1) of the outer-ring raceway groove 5. The outer-ring raceway groove 5 is a groove having an arcuate cross-section extending in the circumferential direction on the inner circumference of the outer ring 1. The outer ring 1 is formed of bearing steel. The outer-ring counterbore portion 7 is a portion having a shape in which part or all of the groove shoulder of the outer-ring raceway groove 5 is removed. The inner diameter of the outer-ring counterbore portion 7 is larger than the inner diameter of the outer-ring shoulder 6.

[0021] On the outer circumference of the inner ring 2, there are provided an inner ring raceway groove 8 with which the balls 3 rollingly contact, an inner ring counterbore portion 9 adjacent to one axial side (the left side in FIG. 1) of the inner ring raceway groove 8, and an inner ring shoulder portion 10 adjacent to the other axial side of the inner ring raceway groove 8. The inner ring raceway groove 8 is a groove with a circular arc-shaped cross-section extending in the circumferential direction on the outer circumference of the inner ring 2. The inner ring 2 is formed of bearing steel. The inner ring counterbore portion 9 is a portion having a shape in which part or all of the groove shoulder of the inner ring raceway groove 8 is removed. The outer diameter of the inner ring shoulder portion 10 is larger than the outer diameter of the inner ring counterbore portion 9.

[0022] As shown in FIGS. 3 and 4, the outer peripheral surface of the inner ring counterbore portion 9 is a tapered surface 11 whose outer diameter gradually decreases as it moves away from the inner ring raceway groove 8. The axial inclination angle α of this tapered surface 11 is in the range greater than 0 degrees and less than or equal to 30 degrees. A counter flat portion (range of Lc in FIG. 4) that is flat in the axial direction is formed between the inner ring raceway groove 8 and the tapered surface 11. Also, a flat width flat portion (range of Lw in FIG. 4) is formed on the axial end surface of the inner ring counterbore portion 9.

[0023] A solid lubricating film is formed on the outer peripheral surface of the inner ring counterbore portion 9. This solid lubricating film has the effect of reducing the friction with the balls 3 when the inner ring 2 is inserted, and can prevent the surface of the balls 3 from being damaged during this insertion. In particular, when a solid lubricating film is formed on the tapered surface 11, the insertion of the inner ring 2 can be performed more smoothly. As this solid lubricating film, black dyeing, diamond-like carbon (DLC), etc. can be adopted. Black dyeing is a porous black oxide film, and lubricity is imparted by holding lubricating oil, etc. in its pores. Also, DLC is a low-friction film having physical properties intermediate between diamond and graphite and has lubricity. In addition to this, molybdenum-based or fluorine-based solid lubricating films can also be adopted. Note that this solid lubricating film is not an essential component and may be omitted in some cases.

[0024] The retainer 4 has a counter-side annular portion 12 that extends in the circumferential direction on one axial side (left side in FIG. 1) with respect to the ball 3, a counter-counter-side annular portion 13 that extends in the circumferential direction on the other axial side (right side in FIG. 1) with respect to the ball 3, and a plurality of column portions 14 that connect the counter-side annular portion 12 and the counter-counter-side annular portion 13 through between the circumferentially adjacent balls 3. The counter-side annular portion 12, the counter-counter-side annular portion 13, and the column portions 14 define a pocket 15 for accommodating the ball 3. When the inner ring 2 is separated, the ball 3 is supported by the pocket 15 so as not to drop radially inward. The counter-side annular portion 12 and the counter-counter-side annular portion 13 position the retainer 4 by fitting into the ball 3. At this time, neither the counter-side annular portion 12 nor the counter-counter-side annular portion 13 is in contact with the outer ring 1 and the inner ring 2.

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

[0026] As shown in FIG. 2, in a holding body (hereinafter referred to as an outer ring assembly) that integrally holds the outer ring 1, the retainer 4, and the ball 3, the ball 3 slightly drops radially inward due to its own weight. The intersection point Y is defined as the point where the center line passing through the contact point X between the ball 3 and the outer ring shoulder 6 at this time and the center O of the ball intersects the surface of the ball 3. Then, the rotation angle β around the center O of the ball 3 in the direction in which the ball 3 drops from this intersection point Y is defined as positive, and the rotation angle β in the reverse direction from the intersection point Y is defined as negative. At this time, for the inner ring 2 inserted into the outer ring assembly, the inner ring counter bore portion 9 first contacts the ball 3 at the contact point Z. When this contact point Z is on the positive rotation angle β side with respect to the intersection point Y, as will be described later (see FIG. 9), the ball 3 that has dropped by its own weight can be smoothly pushed back along the outer ring raceway groove 5 by the contact force with the inner ring 2.

[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 ball 3 and the outer diameter Rc of the inner ring counterbore part 9 when the inner ring 2 is inserted downward from the inner ring counterbore part 9 side, satisfy the relationship of 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 counterbore part 9), no pressure is applied to the ball 3 and no damage or cracking occurs. 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 it deviate from the assumed contact angle.

[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, the second outer ring assembly B' (which integrally holds the outer ring 1, a plurality of balls 3, and the cage 4) is fitted into the 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 periphery of the housing hole 16.

[0030] Next, as shown in Fig. 6, a retaining ring 18 is fitted into a retaining ring groove 17 formed on the inner periphery of the housing hole 16. By this retaining ring 18, the position of the outer ring 1 of the second outer ring assembly B' is fixed. Then, the first outer ring assembly A' is fitted into the portion of the housing hole 16 below the second outer ring assembly B'. At this time, the first outer ring assembly A' is inserted into the housing hole 16 with the counter side annular portion 12 of the cage 4 on the upper side and the counter-counter side annular portion 13 on the lower side. Also, the outer ring 1 of the first outer ring assembly A' is fitted to the inner periphery of the housing hole 16 with an interference fit.

[0031] On the other hand, as shown in Fig. 7, a first inner ring 2 is fitted onto the outer periphery of the shaft body 19. At this time, the first inner ring 2 is fitted onto the outer periphery of the shaft body with the inner ring counter bore portion 9 on the upper side and the inner ring shoulder portion 10 on the lower side. Also, the first inner ring 2 is fitted to the outer periphery of the shaft body 19 with an interference fit. Then, the first outer ring assembly A' is fitted onto the outer periphery of the first inner ring 2 from above. By this fitting, the first angular ball bearing A is in a completed state. In this embodiment, since the outer diameter Rt of the tip of the inner ring counter bore portion 9 of the inner ring 2 is designed to be smaller than the inner diameter Ri of the inscribed circle of the ball 3, the first outer ring assembly A' can be smoothly fitted onto the outer periphery of the first inner ring 2.

[0032] Then, as shown in Fig. 8, the second inner ring 2 is inserted into the second outer ring assembly B' from above with the inner ring counter bore portion 9 on the lower side and the inner ring shoulder portion 10 on the upper side. At this time, the second inner ring 2 is fitted to the outer periphery of the shaft body 19 with an interference fit. Thereby, the second angular ball bearing B is in a completed state.

[0033] As described above, it is possible to assemble the first angular ball bearing A and the second angular ball bearing B to the object.

[0034] In the insertion of the inner ring 2 in Fig. 8, as shown in Fig. 9, at the contact point Z between the ball 3 and the inner ring 2 (inner ring counter bore portion 9), a contact force directed toward the center O of this ball is generated. 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 that becomes larger, 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 will be pulled in the insertion direction as the inner ring 2 is inserted, or the inner ring 2 cannot 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 counterbore portion 9. When the inner ring 2 is inserted 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 counterbore portion 9) first come into contact is on the positive rotation angle β side with respect to the intersection point Y, and between the size C of the ball outer circumferential side gap and the size D of the ball inner circumferential side overlap, the relationship of 1.00 < C / D ≤ 2.50 holds in common. For this reason, 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 up 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 FIG. 11 is a transmission of a full synchromesh mechanism which is a constant-mesh gear mechanism. In this transmission, the gear 30 on the input shaft side and the gear 32 on the output shaft 31 side operate in a meshed state. The shaft 33 rotated by the input shaft and the output shaft 31 is rotatably supported by an inner-ring separated angular ball bearing A. This inner-ring separated angular ball bearing A not only receives a radial load from the input shaft or the output shaft 31, but also simultaneously receives an axial load which is an axial component force.

[0039] The transmission shown in FIG. 12 is a stepless transmission that changes and outputs the rotation of an automobile engine and can change its transmission ratio steplessly. This transmission includes a torque converter 35 connected to the 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 provided in parallel with the input shaft 36, a driving-side V-groove pulley 38 provided on the outer periphery of the input shaft 36 so as to rotate integrally with the input shaft 36, a driven-side V-groove pulley 39 provided 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 driving-side V-groove pulley 38 and the driven-side V-groove pulley 39. The input shaft 36 and the output shaft 37 are rotatably supported by an inner-ring separated angular ball bearing A. This inner-ring separated angular ball bearing A not only receives a radial load from the input shaft 36 or the output shaft 37, but also simultaneously receives an axial load which is an axial component force.

[0040] It should be considered that all the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0041] 1 Outer ring 2 Inner ring 3 Ball 4 Retainer 5 Outer raceway groove 6 Outer race shoulder 7 Outer race counterbore 8 Inner raceway groove 9 Inner race counterbore 10 Inner race shoulder 11 Tapered surface 15 Pocket A Inner ring separable angular ball bearing O Center X Contact point Y Intersection point Z Contact point α Tilt angle β Rotation angle

Claims

1. an outer ring (1); an inner ring (2) coaxially disposed radially inward of the outer ring (1); a plurality of balls (3) incorporated at circumferential intervals between the outer ring (1) and the inner ring (2); a cage (4) for holding the plurality of balls (3), characterized in that on the inner circumference of the outer ring (1), there are provided an outer ring raceway groove (5) with which the balls (3) rollingly contact, an outer ring shoulder (6) adjacent to one axial side of the outer ring raceway groove (5), and an outer ring counterbore portion (7) adjacent to the other axial side of the outer ring raceway groove (5) and having an inner diameter larger than that of the outer ring shoulder (6); on the outer circumference of the inner ring (2), there are provided an inner ring raceway groove (8) with which the balls (3) rollingly contact, an inner ring counterbore portion (9) adjacent to one axial side 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) and having an outer diameter larger than that of the inner ring counterbore portion (9); in an inner ring separable angular ball bearing in which, when the inner ring (2) is separated, the balls (3) are supported so as not to radially drop inward from pockets (15) formed in the cage (4), with the outer ring (1), the cage (4), and the balls (3) integrally held, when the balls (3) radially fall inward due to their own weight, the contact point (X) between the balls (3) and the outer ring shoulder (6) and the center line passing through the center (O) of the balls (3) intersect the surface of the balls (3) at an intersection point (Y). When the rotation angle (β) around the center (O) of the balls (3) in the direction in which the balls (3) fall is defined as positive and the rotation angle (β) in the reverse direction from the intersection point (Y) is defined as negative, when the inner ring (2) is inserted downward from the inner ring counterbore portion (9) side, the contact point (Z) where the balls (3) and the inner ring counterbore portion (9) first come into contact is on the positive side of the intersection point (Y); a relationship of 1.00 < C / D ≦ 2.50 is established between the size C of the ball outer circumferential side clearance, which is the radial clearance between the outer diameter of the circumscribed circle (Ro) of the balls (3) and the groove bottom of the outer ring raceway groove (5) when the balls (3) radially fall inward due to their own weight, and the size D of the ball inner circumferential side overlap, which is the difference between the inner diameter (Ri) of the inscribed circle of the balls (3) and the outer diameter (Rc) of the inner ring counterbore portion (9) when the inner ring (2) is inserted downward from the inner ring counterbore portion (9) side; When the inner ring (2) abuts on the positive rotation angle (β) side of the intersection (Y), the ball (3) that has fallen by its own weight is pushed back along the outer ring raceway groove (5). On the outer peripheral surface side of the inner ring counterbore portion (9), a tapered surface (11) is formed whose outer diameter gradually decreases as it moves away from the inner ring raceway groove (8). An inner ring separable angular ball bearing, characterized in that 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). The inner ring separable angular ball bearing according to claim 1, wherein the axial inclination angle α of the tapered surface (11) satisfies 0° < α ≤ 30°.

3. The inner ring separable angular ball bearing according to claim 1 or 2, wherein a solid lubricating film is formed on the outer peripheral surface of the inner ring counterbore portion (9).

4. The inner ring separable angular ball bearing according to any one of claims 1 to 3, which is used as a bearing for an automobile transmission.

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