JP7708545B2 - Separated inner ring angular contact ball bearing - Google Patents

Description

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

Traditionally, the bearings used in automatic transmissions in automobiles are subjected to not only high radial loads but also axial loads, and so tapered roller bearings with tapered bearings have often been used. However, in recent years, due to the need for improved fuel efficiency in automobiles, angular contact ball bearings have increasingly been used as transmission bearings. Angular contact ball bearings are capable of supporting both radial and axial loads, and have lower torque than tapered roller bearings.

When angular contact ball bearings are used in a transmission, 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.

As a separated type angular ball bearing, for example, the separated inner ring type angular ball bearing disclosed in the following Patent Document 1 is known. The separated inner ring type angular ball bearing disclosed in Patent Document 1 comprises an outer ring, an inner ring arranged coaxially on the radial inside of the outer ring, a number of balls assembled between the outer ring and the inner ring at intervals in the circumferential direction, and a cage that holds the balls.

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 with a shape in which part or all of the outer ring raceway groove has been removed, and the inner ring counterbore is a portion with a shape in which part or all of the groove shoulder of the inner ring raceway groove has been removed.

JP 2008-95929 A

In the case of the separated inner ring angular contact ball bearing disclosed in Patent Document 1, as shown in FIG. 13, for example, when the inner ring 54 is inserted into the retainer (hereinafter referred to as the outer ring assembly) which integrally holds the outer ring 51, the retainer 52, and the balls 53 fitted into the housing hole 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 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 causing the surfaces of the balls 53 and the inner and outer ring raceway grooves to be damaged.

The problem that this invention aims to solve is to provide an angular contact ball bearing with a separated inner ring that allows the inner ring to be smoothly inserted into the outer ring assembly, making it difficult for the ball surfaces and the inner and outer ring raceway grooves to be scratched.

In order to solve the above problems, the present invention provides a separated inner ring angular contact ball bearing having the following configuration.
The outer ring and
an inner ring arranged coaxially on the radially inner side of the outer ring;
A plurality of balls assembled at intervals in a circumferential direction between the outer ring and the inner ring;
a cage for holding the plurality of balls;
an outer ring raceway groove with which the balls roll and contact, an outer ring shoulder adjacent to one side of the outer ring raceway groove in the axial direction, and an outer ring counterbore portion adjacent to the other side of the outer ring raceway groove in the axial direction and having an inner diameter larger than that of the outer ring shoulder,
The outer periphery of the inner ring is provided with an inner ring raceway groove with which the balls roll, an inner ring counterbore portion adjacent to one side of the inner ring raceway groove in the axial direction, and an inner ring shoulder portion adjacent to the other side of the inner ring raceway groove in the axial direction and having an outer diameter larger than that of the inner ring counterbore portion,
In a separated inner ring angular contact ball bearing, the balls are supported so as not to fall out radially inward from pockets formed in the cage when the inner ring is separated,
When the outer ring, the cage, and the balls are held together and the balls drop radially inward due to their own weight, the point at which the contact point between the ball and the outer ring shoulder and the center line passing through the center of the ball intersect with the surface of the ball is defined as an intersection point, and the rotation angle around the center of the ball in the direction in which the ball drops from this intersection point is defined as positive, and the rotation angle in the opposite direction from the intersection point is defined as negative. When the inner ring is inserted downward from the inner ring counterbore side, the contact point where the ball and the inner ring counterbore first come into contact is on the positive side of the intersection point,
a ball circumscribing side gap size C, which is the radial gap between the circumscribing diameter of the ball and the bottom of the outer ring raceway groove when the ball falls radially inward due to its own weight, and a ball inscribing side overlap size D, which is the difference between the inscribing diameter of the ball and the outer diameter of the inner ring counterbore when the inner ring is inserted downward from the inner ring counterbore side, satisfy the relationship 1.00<C/D≦2.50.

By doing this, the abutment point is on the positive side of the intersection, so 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, making the assembly smooth.

In addition, by setting the relationship between the size C of the ball circumscribing side gap and the size D of the ball inscribed side overlap within the above range, the ball is pushed back along the outer ring raceway groove as the inner ring is inserted, allowing for smooth insertion. If the size D of the ball inscribed side overlap is larger than the size C of the ball circumscribing side gap, a tightening margin occurs between the ball and the inner ring when the inner ring is inserted, and pressure is applied to the ball, which may cause scratches or cracks on the ball. In addition, if the value obtained by dividing the size C of the ball circumscribing side gap by the size D of the ball inscribed side overlap is greater than 2.50, the gap between the ball and the inner and outer ring raceway grooves becomes large, and the expected contact angle may not be achieved, or the ball may ride up on the shoulder of the inner and outer rings. For this reason, it is necessary to set the relationship between the size C of the ball circumscribing side gap and the size D of the ball inscribed side overlap within the above range.

It is preferable that the outer diameter surface of the inner ring counterbore portion is formed with a tapered surface whose axial inclination angle α satisfies 0°<α≦30° and whose outer diameter gradually decreases as it moves away from the inner ring raceway groove.

In this way, the contact pressure can be reduced compared to when the balls are in direct contact with the chamfered portion of the inner race 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 shortened, making it possible to shorten 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 race required for processing (see Lw in Figure 4), so it is preferable to keep it in the above range.

It is preferable that a solid lubricant coating is formed on the outer diameter surface of the inner ring counterbore portion.

This reduces friction between the balls and the outer diameter surface of the inner race counterbore, allowing the inner race to be inserted smoothly without damaging the surface of the balls.

The above-mentioned separated inner ring angular contact ball bearing is particularly suitable for use as a bearing in an automobile transmission.

In the separated inner ring angular contact ball bearing of this invention, when the balls of the outer ring assembly are in a dropped state, the point of contact between the balls and the inner ring counterbore is on the positive side of the intersection point defined on the surface of the balls, and the relationship between the size C of the ball circumscribing side gap and the size D of the ball inscribed side overlap is 1.00<C/D≦2.50. 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 counterbore of the inner ring, so the insertion can be done smoothly. Moreover, by setting the relationship between the size C of the ball circumscribing side gap and the size D of the ball inscribed side overlap within the above range, the balls are not caught between the outer ring and inner ring when the inner ring is inserted, and the surface of the balls and the inner/outer ring raceway grooves are less likely to be damaged.

FIG. 1 is a cross-sectional view showing one embodiment of an inner ring separated angular contact ball bearing according to the present invention. FIG. 2 is a cross-sectional view showing a main part of FIG. A diagram showing the dimensional relationship of each member in FIG. Cross-sectional view of the inner ring of the separated inner ring angular contact ball bearing shown in FIG. A cross-sectional view showing one outer ring assembly of the separated inner ring angular contact ball bearing shown in FIG. 1 mounted in a housing hole. 5 , and is a cross-sectional view showing another outer ring assembly being attached to the housing hole. 8 is a cross-sectional view showing the state in which a shaft body provided with one inner ring is inserted, following FIG. FIG. 8 is a cross-sectional view showing a state in which another inner ring is inserted, following FIG. 7. Cross-sectional view showing the contact force acting on the ball when the inner ring is inserted FIG. 2 is a cross-sectional view showing a main portion of a modified example of the separated inner ring type angular contact ball bearing shown in FIG. FIG. 2 is a cross-sectional view showing a first example of application of the separated inner ring type angular contact ball bearing shown in FIG. 1 to an automobile transmission. FIG. 2 is a cross-sectional view showing a second example of application of the separated inner ring type angular contact ball bearing shown in FIG. 1 to an automobile transmission. FIG. 1 is a cross-sectional view of a main portion showing an inner ring insertion process in a conventional inner ring separated angular contact ball bearing.

One embodiment of the 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 radial inside of the outer ring 1, a number 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 balls 3.

The inner circumference of the outer ring 1 is provided with an outer ring raceway groove 5 with which the balls 3 roll, an outer ring shoulder 6 adjacent to one axial side of the outer ring raceway groove 5 (left side in FIG. 1), and an outer ring counterbore 7 adjacent to the other axial side of the outer ring raceway groove 5 (right side in FIG. 1). 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 such that part or all of the groove shoulder of the outer ring raceway groove 5 has been removed. The inner diameter of the outer ring counterbore 7 is larger than the inner diameter of the outer ring shoulder 6.

The inner ring 2 has an inner ring raceway groove 8 with which the balls 3 roll and make contact, an inner ring counterbore portion 9 adjacent to one axial side (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 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 portion 9 is a portion shaped such that part or all of the groove shoulder of the inner ring raceway groove 8 has been removed. The outer diameter of the inner ring shoulder portion 10 is larger than the outer diameter of the inner ring counterbore portion 9.

As shown in Figures 3 and 4, the outer peripheral surface of the inner counterbore portion 9 is 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 in the range of greater than 0 degrees and less than or equal to 30 degrees. An axially flat counter flat portion (range Lc in Figure 4) 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 counterbore portion 9.

A solid lubricating coating is formed on the outer peripheral surface of the inner ring counterbore portion 9. This solid lubricating coating has the effect of reducing 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, if a solid lubricating coating is formed on the tapered surface 11, the inner ring 2 can be inserted more smoothly. As this solid lubricating coating, black dyeing, diamond-like carbon (DLC), etc. can be used. Black dyeing is a porous black oxide coating, and lubricity is imparted by retaining lubricating oil, etc. in the pores. DLC is a low-friction coating with physical properties intermediate between diamond and graphite, and has lubricity. In addition, molybdenum-based and fluorine-based solid lubricating coatings can also be used. Note that this solid lubricating coating is not an essential component, and may be omitted in some cases.

The cage 4 has a counter side annular portion 12 that extends circumferentially on one side in the axial direction relative to the balls 3 (the left side in FIG. 1), an anti-counter side annular portion 13 that extends circumferentially on the other side in the axial direction relative to the balls 3 (the right side in FIG. 1), and a number of columns 14 that connect the counter side annular portion 12 and the anti-counter side annular portion 13 by passing between adjacent balls 3 in the axial direction. The counter side annular portion 12, the anti-counter side annular portion 13, and the columns 14 define a pocket 15 that accommodates the balls 3. When the inner ring 2 is separated, the balls 3 are supported by the pocket 15 so that they do not fall out radially inward. The counter side annular portion 12 and the anti-counter side annular portion 13 are fitted to the balls 3 to position the cage 4. At this time, neither the counter side annular portion 12 nor the anti-counter side annular portion 13 is in contact with the outer ring 1 or the inner ring 2.

Resin is used as the material for the retainer 4. Examples of resin that can be used include polyamides such as PA46 (polyamide 46), PA66 (polyamide 66), and PA9T (polynonamethylene terephthalamide), polyether ether ketone (PEEK), and polyphenylene sulfide (PPS).

As shown in FIG. 2, in the holder (hereinafter referred to as the outer ring assembly) that holds the outer ring 1, the cage 4, and the balls 3 integrally, the balls 3 drop slightly radially inward due to their own weight. 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 the 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. At this time, the inner ring 2 inserted into the outer ring assembly first abuts the balls 3 at the abutment point Z with its inner ring counterbore portion 9. If this abutment point Z is on the positive rotation angle β side of the intersection point Y, the balls 3 that have fallen under their own weight can be smoothly pushed back along the outer ring raceway groove 5 by the abutment force with the inner ring 2, as described later (see FIG. 9).

In addition, in the outer ring assembly, when the ball 3 falls radially inward under its own weight, the size C of the ball circumscribing side gap, which is the radial gap between the circumscribing circle diameter Ro of the ball 3 and the groove bottom of the outer ring raceway groove 5, and the size D of the ball inscribing side overlap, which is the difference between the inscribing circle diameter Ri of the ball 3 and the outer diameter Rc of the inner ring counterbore portion when the inner ring 2 is inserted downward from the inner ring counterbore portion 9 side, have a relationship of 1.00<C/D≦2.50. Therefore, when the ball 3 that has fallen under 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 portion 9), the ball 3 is not subjected to pressure and is not scratched or cracked. Moreover, the gap between the ball 3 and the inner and outer ring raceway grooves 5, 8 does not become large, the expected contact angle does not occur, and the ball 3 does not ride up the inner and outer ring shoulders 6, 10.

An example of the work of assembling the first angular ball bearing A and the second angular ball bearing B to an object will be described below. In the following description, components prefixed with "first" are components of the first angular ball bearing A, and components prefixed with "second" are components of the second angular ball bearing B.

First, as shown in FIG. 5, the second outer ring assembly B' (which holds the outer ring 1, multiple balls 3, and cage 4 together) 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 non-counter side annular portion 13 of the cage 4 facing up and the counter side annular portion 12 facing down. In addition, the outer ring 1 of the second outer ring assembly B' is fitted into the inner circumference of the housing hole 16 with a tightening margin.

Next, as shown in FIG. 6, a retaining ring 18 is attached to the retaining ring groove 17 formed on the inner circumference of the housing hole 16. The position of the outer ring 1 of the second outer ring assembly B' is fixed by this retaining ring 18. After that, the first outer ring assembly A' is fitted into the part 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 retainer 4 facing up and the anti-counter side annular portion 13 facing down. In addition, the outer ring 1 of the first outer ring assembly A' is fitted into the inner circumference of the housing hole 16 with a tightening margin.

On the other hand, as shown in FIG. 7, the first inner ring 2 is attached to the outer circumference of the shaft body 19. At this time, the first inner ring 2 is attached to the outer circumference of the shaft body 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 to the outer circumference of the shaft body 19 with a tightening margin. After that, the first outer ring assembly A' is attached to the outer circumference of the first inner ring 2 from above. With this attachment, the first angular ball bearing A is in a completed state. 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 smoothly attached to the outer circumference of the first inner ring 2.

Then, as shown in FIG. 8, insert the second inner ring 2 into the second outer ring assembly B' from above, with the inner ring counterbore portion 9 facing downward and the inner ring shoulder portion 10 facing upward. At this time, the second inner ring 2 is fitted onto the outer periphery of the shaft body 19 with a tightening margin. This completes the second angular ball bearing B.

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

When the inner ring 2 is inserted as shown 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 can be broken down into a horizontal component _FH that pushes the ball 3 back toward the outer ring raceway groove 5, and a vertical component _FV that pulls the ball 3 downward along the insertion direction of the inner ring 2. When the contact point Z is at a positive position of the rotation angle β with respect to the intersection point Y (the position in the direction in which the ball 3 falls), the horizontal component _FH is larger than the vertical component _FV , and the ball 3 can be smoothly pushed back toward the outer ring raceway groove 5.

In contrast, as shown in Figure 13, when the abutment point Z is in a negative position of the rotation angle β with respect to the intersection point Y (a position in the opposite direction to the direction in which the ball 3 falls), the horizontal component _FH ' and the vertical component _FV ' are approximately the same size, or the vertical component _FV ' is larger than the horizontal component _FH ', and there is a risk that the ball 3 will be pulled in the insertion direction as the inner ring 2 is inserted, or that the inner ring 2 cannot be inserted smoothly.

Figure 10 shows the main part of a modified version of the inner ring separated angular contact ball bearing A shown in Figure 1. This modified version differs from the previously described configuration only in that the tapered surface 11 is not formed on the inner ring counterbore portion 9. However, when the inner ring 2 is inserted into the outer ring assembly, the abutment point Z where the balls 3 of the outer ring assembly and the inner ring 2 (inner ring counterbore portion 9) first abut is located on the positive rotation angle β side of the intersection point Y, and the relationship between the size C of the ball circumscribing side gap and the size D of the ball inscribing side overlap is 1.00 < C / D ≦ 2.50. Therefore, in this modified version, as in the above, the balls 3 can be smoothly pushed back toward the outer ring raceway groove 5 as the inner ring 2 is inserted, and it is possible to prevent the balls 3 from being scratched or cracked due to pressure being applied to the balls 3, or from riding up onto the inner and outer ring shoulders 6 and 10 without achieving the expected contact angle.

As shown in Figures 11 and 12, the above-mentioned separated inner ring angular contact ball bearing A can be used as a bearing for an automobile transmission.

The transmission shown in FIG. 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 side 31 are in mesh with each other when operating. Shaft 33, which is driven to rotate by the input shaft and 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 output shaft 31, but also simultaneously receives an axial load, which is an axial component force.

The transmission shown in Fig. 12 is a continuously variable transmission that can change the speed of the rotation of an automobile engine and output the rotation, and can change the speed ratio steplessly. This transmission has 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 type angular ball bearing A. This separated inner ring angular contact ball bearing A not only receives radial loads from the input shaft 36 or output shaft 37, but also simultaneously receives axial loads, which are axial component forces.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

Reference Signs List 1 Outer ring 2 Inner ring 3 Ball 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 Pocket A Inner ring split type angular contact ball bearing O Center X Contact point Y Intersection Z Contact point α Tilt angle β Rotation angle

Claims (4)

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) assembled at intervals in the circumferential direction between the outer ring (1) and the inner ring (2);
and a cage (4) for holding the plurality of balls (3),
The inner circumference of the outer ring (1) is provided with an outer ring raceway groove (5) with which the balls (3) roll and come into 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, a point where a center line passing through a contact point (X) between the balls (3) and the outer ring shoulder portion (6) and a center line passing through the center (O) of the balls (3) intersect 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 a 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, a contact 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),
a relationship of 1.00<C/D≦2.50 is established between a ball circumscribing side gap size C, which is a radial gap between the circumscribing circle diameter (Ro) of the ball (3) and the groove bottom of the outer ring raceway groove (5) when the ball (3) drops radially inward due to its own weight, and a ball inscribing side overlap size D, which is a difference between the inscribing circle diameter (Ri) of the ball (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 point (Y), the balls (3) that have fallen due to their own weight are pushed back along the outer ring raceway groove (5),
A tapered surface (11) is formed on the outer peripheral surface side 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),
An inner ring separated angular contact 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) . 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°. The separated inner ring angular contact ball bearing according to claim 1 or 2, in which a solid lubricant coating is formed on the outer peripheral surface of the inner ring counterbore portion (9). 4. The separated inner ring angular contact ball bearing according to claim 1, which is used as a bearing for an automobile transmission.