JP7270409B2 - ball bearing - Google Patents

Description

The present invention relates to a ball bearing provided with a resin retainer.

In EVs (electric vehicles) and PHEVs (plug-in hybrid electric vehicles), in order to obtain driving force comparable to that of engine-driven vehicles, electric motors, which are driving sources, are increasing in rotation speed. In order to support this high-speed rotating shaft, ball bearings suitable for high-speed operation are used.

Some ball bearings designed for high-speed rotation use a resin retainer. In particular, crown-type retainers are used when the assemblability and cost of the bearing are important. In general, crown-shaped retainers have a plurality of pocket portions that are open on the inner periphery, the outer periphery, and one side surface in the axial direction of the retainer. The pocket portion is formed in a concave curved surface shape that wraps around the ball. The opening width of the pocket portion on one side surface in the axial direction of the retainer is set smaller than the diameter of the ball. The elastic deformation that widens the width of the opening is maintained by pressing the opening edge of the pocket portion on one axial side of the retainer toward one axial direction against the plurality of balls arranged between the inner and outer raceway surfaces. The ball is placed in the pocket through the opening of the vessel. The elastically restored pocket portion becomes engageable with the ball toward the other axial direction. The engagement restricts the movement of the retainer in the other axial direction.

In the case of a general crown-shaped retainer, deformation due to centrifugal force during high-speed rotation is a problem. That is, since the protruding portion of the retainer extending in one axial direction to form the pocket portion is a cantilever beam, the pocket portion is inclined radially outward in one axial direction due to centrifugal force. , the annular portion of the retainer is twisted accordingly. For this reason, there is concern that the pocket portion will interfere with the balls and the outer ring, resulting in the generation of abrasion powder, abnormal heat generation, and shortened service life.

In order to suppress the influence of such centrifugal force, in the crown-shaped retainer of Patent Document 1, the axial thickness of the intermediate portion located between the pocket portions adjacent in the circumferential direction is reduced to reduce the thickness of the pocket portion. The weight of the protruding portion forming the pocket portion is reduced while securing the depth in the axial direction. Further, by making the thickness in the axial direction at the intermediate portion larger than the thickness in the axial direction at the bottom of the pocket portion, the strength of the retainer is ensured.

Further, in the retainer disclosed in Patent Document 2, the retainer is composed of a crown-shaped retainer body and a metal deformation preventing member attached to the tip of the protruding portion of the retainer body, and the protruding portion is deformed by centrifugal force. It is prevented from tilting radially outward.

Further, in the crown-shaped retainer disclosed in Patent Document 3, the outer diameter of the protruding portion forming the pocket portion is gradually reduced from the axially intermediate portion toward the distal end, thereby reducing the weight and reducing the influence of centrifugal force. are doing. Furthermore, by setting the contact between the balls and the pocket portion at a position radially inward of the pitch circle diameter of the balls, the radially inward force from the balls acts on the retainer to deformation of the retainer is suppressed.

JP 2016-169766 A JP 2007-285506 A Japanese Unexamined Patent Application Publication No. 2013-200006

However, when the movement of the retainer in the other axial direction is restricted by the engagement of the pocket portions and the balls as in Patent Document 1, it is necessary to extend the pocket portions in one axial direction from the center of the balls with a sufficient margin. be. Therefore, the tip of the pocket is easily affected by the centrifugal force, and there is a limit to suppressing deformation of the retainer due to the centrifugal force.

In addition, if a deformation prevention member is attached to the crown-shaped retainer main body to resist centrifugal force as in Patent Document 2, an additional assembly process and separate component costs are required, resulting in an increase in cost. Furthermore, there is a concern that the deformation prevention member will fall off.

Further, as in Patent Document 3, if the outer diameter of the protruding portion forming the pocket portion is gradually reduced from the intermediate position in the axial direction to the tip, it is possible to weaken the influence of the centrifugal force, but the engagement between the pocket portion and the ball is the same as in Patent Document 1 in that the movement of the retainer in the other axial direction is restricted by . Further, when the force from the balls directed radially inward is applied to the pocket portion to suppress the deformation of the cage due to the centrifugal force, if the cage is deformed due to the centrifugal force, the tip portion of the pocket portion may be deformed. There is a concern that the radially inner side is directly connected to strong contact with the ball, and abnormal wear progresses at the contact portion.

Electric motors for EVs and PHEVs continue to rotate at high speeds, and the ball bearings that support the rotating shafts of electric motors have a dmn value of 2,000,000. may exceed. When aiming for a ball bearing that can be used in such high-speed rotation, it is important not only to prevent abnormal heat generation by countering centrifugal force, but also to prevent normal heat generation, so the shear resistance of the lubricant between the cage and the balls is important. can also be a problem. If the temperature of the cage can be maintained at 120°C or less, relatively inexpensive engineering plastics can be used. This is because it will have to be adopted.

In view of the above background, the problem to be solved by the present invention is to provide a ball bearing in which the pocket portion of the resin retainer is open on one side surface in the axial direction, while suppressing an increase in cost, and To suppress the deformation of a ball and to suppress the shear resistance of lubricating oil between a pocket part and a ball.

In order to achieve the above object, the present invention provides an outer raceway ring having an outer raceway surface, an inner raceway ring having an inner raceway surface, the outer raceway surface and the inner raceway surface. a plurality of balls arranged between the raceway surface of the ball and a resin retainer for evenly arranging the plurality of balls in a circumferential direction, wherein the retainer determines the circumferential positions of the balls In a ball bearing having pocket portions at a plurality of locations in the circumferential direction, the pocket portions opening to one side surface of the retainer in the axial direction, the outer bearing ring and the inner raceway further comprising a locking member attached to the bearing ring of one of the rings, the locking member axially relative to the cage so as to restrict movement of the cage in the other axial direction; It has a facing portion disposed on the other side, and when the depth in the axial direction of the pocket portion is H and the diameter of the ball is d, the relationship between H and d is 0.15d≤H≤0.65d. and the one raceway ring has a seal groove portion that is radially deep at a position on the other side in the axial direction of the raceway surface of the raceway ring and continues along the entire circumference in the circumferential direction, and A configuration is adopted in which the stop member is formed of a metal plate-made core bar and an elastomer attached to the core bar, and is composed of a seal attached to the seal groove.

According to the above configuration, it is possible to restrict the movement of the retainer in the other axial direction by engaging the retainer with the facing portion of the locking member attached to one bearing ring. Therefore, it is possible to set the relationship between the axial depth H of the pocket portion and the diameter d of the ball to H≦0.65d. Here, if H≤0.65d, the protruding portion is shortened in the axial direction and the weight is reduced, so that the retainer is less susceptible to centrifugal force during high-speed rotation, and deformation of the retainer due to centrifugal force occurs. can be suppressed, and the shear resistance between the pocket portion and the ball can be suppressed. Further, when H>0.65d, the depth of the pocket portion is the same as that of the conventional example that can restrict the movement of the retainer in the other axial direction only by the engagement between the pocket portion and the ball. There is no meaning in adopting the regulation by the facing portion of the . Also, if H<0.15d, it becomes difficult to maintain the circumferential position of the ball at the pocket portion. A bearing ring having a seal groove and a seal formed of a metal plate core and an elastomer and attached by press-fitting into the seal groove all have common structures in sealed ball bearings. Therefore, one bearing ring and locking member can be realized based on the specifications of a bearing ring and a seal for a known sealed ball bearing, and an increase in cost can be suppressed.

Preferably, the relationship between the depth H of the pocket portion and the diameter d of the ball is set to H<0.5d. By doing so, deformation of the retainer due to centrifugal force and the aforementioned shear resistance can be further suppressed. In the case of H<0.5d, there are no claws for holding the balls in the pocket portions as in the conventional case, and the balls can be put in the respective pocket portions simply by placing the retainer at a predetermined position.

Further, an axial clearance is set between the locking member and the retainer, and one of the opposing portion of the locking member and the retainer is circularly spaced between the other. It is preferable to have two or more protrusions forming a space that narrows in the axial direction in the circumferential direction, and that the protrusions are arranged so as to be spaced apart in the circumferential direction. With this configuration, since an axial clearance is provided between the retainer and the locking member, lubricating oil enters between the facing portion of the locking member and the two opposing side surfaces of the retainer to form an oil film. In addition, if the lubricating oil is dragged in the narrower direction of the wedge-shaped space formed between the projections on one side and the other side between the two sides, a wedge effect that generates dynamic pressure is generated, so that the oil film can be promoted, and wear of the retainer and the opposing portion can be prevented. When the relative peripheral speed difference between the retainer and the locking member increases as the number of protrusions increases, the protrusions arranged at intervals in the circumferential direction circulate at high speed and drag the lubricating oil. A continuous oil film is maintained in the circumferential direction on the side of the , creating a continuous wedging effect between each projection and the other side, thereby increasing the thickness of the oil film that completely separates the projection from the other side. can also be realized. That is, when the peripheral speed difference is equal to or greater than a predetermined value, the friction state between the retainer and the engaging member can be changed to the fluid lubrication state. In the fluid-lubricated state, the movement of the retainer in the other axial direction is regulated by the non-contact engagement between the opposing portion of the locking member and the retainer through the oil film, so that the wear described above can be effectively prevented. can be done.

For example, the facing portion of the locking member may have the two or more protrusions, and these protrusions may be formed of the elastomer. In this way, the projections can be formed during the molding of the elastomer, and the dimensional accuracy of the projections can be improved as compared with the case where the projections are press-worked on the metal core.

Of the outer bearing ring and the inner bearing ring, the one bearing ring and the other bearing ring opposite to the one bearing ring have a seal sliding surface extending along the entire circumference in the circumferential direction, and A stop member has a seal lip formed by the elastomer so as to slide circumferentially against the seal sliding surface, and the seal lip is circumferentially disposed between the seal sliding surface and the seal sliding surface. two or more elastic projections forming a space that axially narrows toward the elastic projections, the elastic projections being spaced apart in the circumferential direction, and the distance between the circumferentially adjacent elastic projections being: It is preferable that the oil passage communicates between the inside of the bearing and the outside of the bearing. In this way, as the bearing rotates, each elastic projection of the seal lip drags the lubricating oil in the oil passage toward the narrow wedge-shaped space formed between the seal sliding surface and the wedge effect. Therefore, the formation of an oil film can be accelerated, and when the circumferential speed difference between the locking member and the other raceway ring exceeds a predetermined value, the frictional state between the seal lip and the seal sliding surface can be brought into a fluid lubrication state. be possible. As a result, wear of the seal lip can be suppressed, seal torque can be reduced to the same level as when a non-contact type seal is employed as the locking member, and high-speed rotation of the ball bearing can be handled. Further, since the particle size of foreign matter that can pass through the oil passage can be determined based on the projection height of the elastic protrusion, it is possible to prevent foreign matter having a predetermined particle size from entering.

The retainer may be made of engineering plastic. As mentioned above, it is possible to suppress deformation of the cage due to centrifugal force and prevent abnormal heat generation, as well as heat generation due to shear resistance. manufacturing cost can be suppressed.

As described above, the present invention can suppress the deformation of the retainer due to the centrifugal force and suppress the shear resistance of the lubricating oil between the pocket portion and the balls by adopting the above configuration.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the ball bearing which concerns on 1st embodiment of this invention Conceptual diagram showing an example of use of the ball bearing according to the first embodiment Sectional perspective view of the ball bearing of FIG. FIG. 2 is a perspective view showing one axial side of the retainer of FIG. 1 ; FIG. 2 is a perspective view showing the other axial side of the retainer of FIG. 1 ; FIG. 2 is a perspective view showing one axial side of the locking member in FIG. 1 ; Partially enlarged cross-sectional view of a cross section taken along line VII-VII in FIG. Sectional drawing which shows the ball bearing which concerns on 2nd embodiment of this invention Enlarged view of the vicinity of the seal lip in Fig. 8 FIG. 9 is a partially enlarged side view of one axial side of the seal lip of FIG. 8 ; Partially enlarged cross-sectional view of a cross section taken along line XI-XI in FIG.

A first embodiment as an example of a ball bearing according to the present invention will be described with reference to FIGS. 1 to 7. FIG.

A ball bearing 10 shown in FIG. A retainer 3 and a plurality of balls 4 arranged so as to be arranged in a circumferential direction at a predetermined pitch by the retainer 3 are provided.

Here, the direction along the rotation center line of the retainer is called the "axial direction". Also, the direction along the circumference of the cage around the rotation center line is referred to as the "circumferential direction". A direction orthogonal to the rotation center line of the retainer is called a "radial direction". Also, the concept of one axial direction and the other axial direction is the direction considered with respect to the retainer. Also, the inner diameter or outer diameter means the diameter of a virtual inscribed circle or virtual circumscribed circle concentric with the rotation center line of the retainer. In FIG. 1, the left-right direction corresponds to the axial direction, with one axial direction being left and the other axial direction being right. In FIG. 1, the radial direction corresponds to the vertical direction, the upward direction corresponds to radially outward, and the downward direction corresponds to radially inward.

The outer bearing ring 1 is an annular bearing component having an inner circumference including an outer raceway surface 1a. The inner race 2 is an annular bearing component having an outer circumference that includes an inner raceway surface 2a. The outer raceway surface 1a and the inner raceway surface 2a each consist of a raceway groove having an arc-shaped cross section. The illustration shows bearing rings 1 and 2 for a deep groove ball bearing and a seal bearing.

In general, one of the outer bearing ring 1 and the inner bearing ring 2 is fixed for rotation with a rotating shaft (not shown) and the other is a housing (not shown) stationary relative to the rotating shaft. fixed to In the illustrated example, a ball bearing that can be operated with a dmn of 2,200,000 is assumed. For this reason, the ball bearing 10 is used in an oil lubrication system in which the inside of the bearing is lubricated with lubricating oil (not shown, hereinafter the same). As an application for such high-speed operation, for example, as conceptually shown in FIG. The motor 5 is, for example, an electric motor that serves as a drive source for an automobile.

As shown in FIGS. 1 and 3, the plurality of balls 4 are arranged between the outer raceway surface 1a and the inner raceway surface 2a. The retainer 3 evenly arranges a plurality of balls 4 in the circumferential direction.

As shown in FIG. 4, the retainer 3 has pocket portions 3a at a plurality of locations in the circumferential direction for maintaining the circumferential positions of the balls 4. The whole of the bearing components connected so that they can rotate together in the circumferential direction.

The retainer 3 is made of resin. Here, "made of resin" means that the entire retainer 3 is made of resin. The concept of the resin includes a single type, a mixture of two or more types, and a mixture of reinforcing materials (such as glass fiber, carbon fiber, etc.) mixed with one or more types of resin as a base material (so-called fiber reinforced resin). is wrapped. When making a ball bearing suitable for high-speed rotation, it is preferable to employ a fiber-reinforced resin.

The retainer 3 employs an engineering plastic as the aforementioned resin. Engineering plastics generally refer to plastics having a heat resistance of 100° C. or higher and 120° C. or lower, a strength of 50 MPa or higher, and a flexural modulus of 2.4 GPa or higher.

Main engineering plastics include, for example, polyamides (PA, PA6, PA9, PA46, PA66), polyacetal (POM), polycarbonate (PC), polybutylene terephthalate (PBT), and the like. (PA46 or 66 + glass fiber) and (PA9T + carbon fiber).

The entire retainer 3 is integrally formed by injection molding using an axially split mold.

As shown in FIGS. 1 and 4, the pocket portion 3a is a concave portion that forms a space for housing the ball 4, and has a shape that is open on one axial side surface of the retainer 3. As shown in FIG. The plurality of pocket portions 3a are arranged at a constant pitch in the circumferential direction. Balls 4 are housed in pocket portions 3a through openings on one axial side surface of cage 3, as in a general crown-shaped cage.

As shown in FIGS. 4 and 5, cylindrical surfaces 3b and 3c are formed on the outer and inner circumferences of the retainer 3, respectively, at positions on the other side in the axial direction than the plurality of pocket portions 3a. The outer cylindrical surface 3 b defines the outer diameter of the retainer 3 . The inner cylindrical surface 3 c defines the inner diameter of the retainer 3 . Of the outer periphery of the retainer 3, the outer diameter surface of the portion between the pocket portions 3a adjacent in the circumferential direction is an arcuate surface having the same diameter as the cylindrical surface 3b on the outer peripheral side. Of the inner circumference of the retainer 3, the inner diameter surface of the portion between the pocket portions 3a adjacent in the circumferential direction is an arcuate surface having the same diameter as the cylindrical surface 3c on the inner circumference side.

As shown in FIG. 4, on one side surface of the retainer 3 in the axial direction, the portion between the tips of the pocket portions 3a adjacent in the circumferential direction forms an arcuate width surface 3d that continues along the circumferential direction. It's becoming Here, the width surface refers to a surface portion at one end that defines the width (total length in the axial direction) of a certain member.

As shown in FIGS. 1 and 5, the other side surface of the retainer 3 in the axial direction consists of a surface portion extending between the other peripheral edges in the axial direction of the cylindrical surfaces 3b and 3c. An inclined surface 3e is formed from the other peripheral edge in the axial direction of the outer cylindrical surface 3b. The inclined surface 3e has a constant inclination in the axial direction toward the radially inward direction. A flat surface 3f extending radially and circumferentially from the inclined surface 3e is formed. The flat surface 3f is continuous with a constant radial width along the entire circumference. An inclined surface 3g is formed from the other peripheral edge in the axial direction of the inner cylindrical surface 3c to the flat surface 3f. The inclined surface 3g has a constant inclination angle on the other side in the axial direction toward the radially outward direction.

As shown in FIGS. 1 and 4, the pocket portion 3a has a shape in which the outer and inner circumferences of the retainer 3 are also opened. A portion of the pocket portion 3a that can come into contact with the ball 4 has a concave spherical shape along the ball 4. - 特許庁That is, the ball 4 faces the pocket portion 3a both in the circumferential direction, the other in the axial direction, and radially inwardly and outwardly.

A pocket clearance is set between the pocket portion 3a and the ball 4. - 特許庁The retainer 3 can move freely with respect to the plurality of balls 4 within the pocket clearance. When the retainer 3 is deformed by centrifugal force and the pocket clearance becomes negative, the pocket portion 3a interferes with the balls 4 and they come into contact with each other abnormally strongly. If the pocket clearance is increased, the interference is less likely to occur, but the acoustic characteristics deteriorate. That is, when the ball bearing rotates at a high speed, the ball 4 comes into contact with the pocket portion 3a due to the advance and lag of the ball 4 when entering and exiting the load bearing region of the ball bearing. This contact maintains the position of the balls 4 in the circumferential direction. It is preferable to set the pocket clearance to 0.2 mm or less in order to bring the acoustic characteristics at high speed rotation to a practical level.

Here, as shown in FIG. 1, the axial depth of the pocket portion 3a is H, and the diameter of the ball 4 (ball diameter) is d. The depth H corresponds to the distance between an imaginary radial plane in contact with the tip of the pocket portion 3a and an imaginary radial plane in contact with the bottom of the pocket portion 3a. Here, the virtual radial plane is a virtual plane orthogonal to the rotation centerline of the retainer 3 . The tip of the pocket portion 3a is the portion of the pocket portion 3a that is located on one side in the axial direction. The bottom of the pocket portion 3a is the portion of the pocket portion 3a that is located at the other end in the axial direction. The depth H corresponds to the axial length of a protruding portion of the retainer 3 protruding in one axial direction so as to form the pocket portion 3a.

During high-speed rotation of the ball bearing, when the ball 4 comes into contact with the pocket portion 3a in the circumferential direction due to the lead/lag of the ball 4 as described above, the ball 4 must not climb over the pocket portion 3a. In order to prevent such a situation, 0.15d≦H is set.

On the other hand, as the depth H of the pocket portion 3a is reduced, the pocket portion 3a can be made smaller in the radial direction and the circumferential direction, and the cage shape can be made less susceptible to centrifugal force. This is also advantageous in that by shortening the radial length of the ring portion of the retainer 3, the facing range between the pocket portion 3a and the balls 4 is reduced, and the shear resistance of the lubricating oil between them is suppressed. . That is, the smaller the H/d, the smaller the facing area between the balls 4 and the pocket portions 3a. As a result, the shear resistance of the lubricant between the balls 4 and the pocket portions 3a becomes smaller. can be reduced. Further, when the shear resistance is reduced, the amount of heat generated in the vicinity of the retainer 3 can be suppressed, which is suitable for high-speed rotation as in the present embodiment.

Table 1 shows the results of evaluating the ball overriding the pocket and the deformation of the cage due to centrifugal force at various H/d.

In Table 1, the item "climbing over" shows the evaluation results of the above-mentioned climbing prevention performance, the item "influence of centrifugal force" shows the evaluation results of the performance of suppressing pocket deformation due to centrifugal force, and the item " The item "Shear resistance" indicates the evaluation result of the shear resistance of the lubricating oil between the ball and the pocket portion, and the item "Comprehensive evaluation" indicates the evaluation result of the suitability of the ball bearing for high-speed operation. In each of these items, "⊚" means very good, "◯" means good, and "X" means bad.

As shown in Table 1, when H>0.65d, the pockets are such that the movement of the cage in the other axial direction can be restricted only by the engagement between the pocket portions and the balls, as in the case of the conventional crown-shaped cage. However, if an engineering plastic retainer is used, there is a particular concern that the pockets will interfere with the balls at high-speed rotation where the dmn value exceeds 2,000,000.

Further, when H≦0.65d is set, the axial length of the protruding portion for forming the pocket portion 3a of the retainer 3 is shortened, the weight of the protruding portion is reduced, and the retainer 3 is made centrifugal. You can make it less susceptible to force.

In the illustrated cage 3, H<0.5d. More specifically, H is set to 0.25d or less.

When H≤0.5d, the pocket portion 3a is not undercut in the above-described injection molding, and the shape of the pocket portion 3a is not distorted when the mold is released. Therefore, the dimensional accuracy of the pocket portion 3a is improved.

If H<0.5d, the opening width of the pocket portion 3a on one axial side surface of the retainer 3 must be smaller than the diameter d of the ball 4 . Therefore, the pocket portion 3a cannot engage with the ball 4 toward the other axial direction. Even if 0.5d<H≦0.65d is set and the shape of the pocket portion is made to be a shape capable of coming into contact with the ball 4 toward the other side in the axial direction, the contact is shallow. Therefore, when the ball bearing rotates at a high speed, there is concern that the movement of the retainer 3 in the other axial direction may be restricted only by the contact thereof. In particular, when H<0.5d, when the ball 4 comes into contact with the pocket portion 3a, the direction of contact becomes close to the other axial direction, and the component force of the ball 4 pushing the pocket portion 3a toward the other axial direction increases. . Since the induced thrust load, which is the sum of the component forces in the other axial direction from the balls 4, is applied to the cage 3, the cage 3 is moved in the other axial direction.

Therefore, a structure described later is employed in which the retainer 3 can be engaged with one of the inner and outer races 1 and 2 in the other axial direction. By restricting the movement of , the relationship between the depth H and the ball diameter d can be set to H≦0.65d.

Specifically, as shown in FIGS. 1 and 3 , the ball bearing 10 further comprises a locking member 7 attached to the outer bearing ring 1 . The outer raceway ring 1 has a seal groove portion 1b at the other position in the axial direction than the raceway surface 1a of the raceway ring 1 . The seal groove portion 1b has a depth in the radial direction and continues along the entire circumferential direction. The seal groove portion 1b is located between the shoulder portion forming the raceway surface 1a and the width surface on the other side in the axial direction of the raceway ring 1, and has the illustrated cross-sectional shape over the entire circumference.

The locking member 7 consists of a seal attached to the seal groove 1b. The locking member 7 is formed of a cored bar 7a made of a metal plate and an elastomer 7b attached to the cored bar 7a. The illustrated locking member 7 is of a so-called non-contact type that does not come into contact with the inner bearing ring 2 .

The locking member 7 has a base end portion 7c held in the seal groove portion 1b, a seal lip 7d forming a labyrinth seal between the annular groove portion 2b and a seal lip 7d arranged on the other side in the axial direction of the retainer 3. and a portion 7e.

The cored bar 7a is an annular one continuous in the circumferential direction. The cored bar 7a is generally formed by pressing a cold-rolled steel plate. The core metal 7a includes an annular plate portion extending along the entire circumference along the radial direction and the circumferential direction, a base end portion of the annular plate portion bent in one direction in the axial direction from the seal groove 1b side, and an annular plate portion. It has a tip bent in one direction in the axial direction from the annular groove 2b side. The base end portion of the cored bar 7a extends along the axial direction at a position facing the outer bearing ring 1 in the axial direction. The tip portion of the cored bar 7a is inclined in one axial direction with respect to the radial direction at a position facing the retainer 3 in the axial direction. The base end portion and the tip portion of the core bar 7a improve the deformation resistance of the facing portion 7e against the induced thrust load, and suppress the inclination of the facing portion 7e when restricting the movement of the retainer 3 in the other axial direction. effective.

The elastomer 7b is a polymer having rubber elasticity. Examples of the elastomer 7b include synthetic rubbers such as nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), and acrylic rubber (ACM). Generally, these synthetic rubbers are adhered to the core metal 7a by vulcanization molding using a mold.

The proximal end portion 7c is formed by the elastomer 7b so as to enclose the proximal end portion of the metal core 7a. The base end portion 7c is press-fitted into the seal groove portion 1b so as to be held in the seal groove portion 1b so as not to move in both axial directions. By this holding, the locking member 7 is attached to the seal groove portion 1b.

The seal lip 7d is formed by the elastomer 7b so as to extend inwardly of the annular groove portion 2b from the bonding surface of the metal core 7a to the tip portion.

The facing portion 7e is a portion axially facing the other side surface of the retainer 3 in the axial direction. Includes portion and tip. One axial side surface of the opposing portion 7e is formed by an elastomer 7b so as to connect the base end portion 7c and the seal lip 7d and to cover one axial side surface of the annular plate portion of the core metal 7a. there is

As shown in FIG. 1, radial and axial clearances are set between the retainer 3 and the locking member 7 . Therefore, lubricating oil inside the bearing is supplied between the locking member 7 and the retainer 3 . When the retainer 3 rotates at a high speed, the lubricating oil that is entrained in the retainer 3 is sent toward the outer bearing ring 1 side by the action of centrifugal force. Lubricating oil becomes easier to reach.

The retainer 3 may be of a rolling-element-guided type or a race-guided type. If a clearance larger than the pocket clearance is set between the cage 3 and the outer bearing ring 1, between the cage 3 and the inner bearing ring 2, and between the cage 3 and the locking member 7, The retainer 3 is of a rolling-element-guided type that is radially guided by a plurality of balls 4 . In the case of the rolling element guide type shown in the figure, since the radial clearance between the locking member 7 and the cage 3 is larger than the above-described pocket clearance, the cage 3 guided by the balls 4 does not reach the locking member 7. is not strongly pushed in the radial direction, and a clearance is secured between the retainer 3 and the bearing rings 1, 2 to secure an inflow path for lubricating oil between the locking member 7 and the retainer 3. can also

As shown in FIGS. 3 and 6, the opposing portion 7e of the locking member 7 has two or more projections 7f having heights in one direction in the axial direction. These projections 7f are arranged so as to be spaced apart in the circumferential direction. The projection 7f extends straight in the radial direction with a constant height in the axial direction.

As shown in FIG. 7, the projection 7f forms a wedge-shaped space with the flat surface 3f that narrows in the axial direction in the circumferential direction. The aforementioned wedge shape is defined based on the wedge angle formed by the tangential line to the projection 7f and the flat surface 3f in the cross-sectional view of FIG. The protrusion 7f is semicircular in any cross section along the circumferential direction. Therefore, the wedge angle becomes smaller as it approaches the tip of the projection 7f (the highest position in the projection 7f in the axial direction). With such a shape of the protrusion 7f that gradually decreases the wedge angle, the protrusion 7f does not have a sharp tip toward the flat surface 3f. Therefore, even if the tip of the protrusion 7f is pressed against the oil film by an induced thrust load during high-speed rotation of the ball bearing, it is possible to prevent the oil film from running out.

The aforementioned axial clearance c is set between the tip of the projection 7f and the flat surface 3f. Of the axial one side surface of the locking member 7 shown in FIGS. 1, 6, and 7, the portion other than the projection 7f cannot contact the retainer 3 in the axial direction.

When the ball bearing rotates, lubricating oil enters the gaps between adjacent projections 7f, and as the retainer 3 rotates, the projections 7f slide against the flat surface 3f. The lubricating oil existing in the gap is dragged by the protrusion 7f between the protrusion 7f and the flat surface 3f. At this time, the lubricating oil is dragged toward the narrow side of the wedge-shaped space to generate dynamic pressure, and a wedge effect is produced in which the pressure of the oil film increases. This effect promotes the formation of an oil film and thickens the oil film between the projection 7f and the flat surface 3f. Further, when many projections 7f rotate at a high speed, an oil film is formed continuously on the entire circumference of the flat surface 3f, and the wedge effect of the projections 7f is continuously produced. Therefore, when the peripheral speed difference between the retainer 3 and the locking member 7 is equal to or greater than a predetermined value, an oil film is formed to completely separate the projections 7f and the flat surface 3f. Therefore, the friction state between the retainer 3 and the locking member 7 becomes a fluid lubrication state.

Since the peripheral speed difference between the retainer 3 and the locking member 7 is also important for realizing the fluid lubricating state, the protrusion 7f is particularly effective when the outer bearing ring 1 is a stationary ring. For example, when the rotating shaft 5a of the motor 5 shown in FIG. Abrasion of the flat surface 3f does not substantially occur. The projections 7f may be provided in a manner capable of realizing a fluid lubricating state with a predetermined lubricating oil, oil temperature, and peripheral speed difference. not limited to

When the retainer 3 shown in FIG. 1 is loaded with an induced thrust load and tries to move in the other axial direction beyond the aforementioned clearance c, the flat surface 3f shown in FIG. In the case of fluid lubrication, it engages with each projection 7f in a non-contact manner via the oil film. This engagement prevents further movement of the retainer 3 (see also FIG. 1) in the other axial direction, so that the retainer 3 does not come off in the other axial direction.

Of course, the axial clearance c is set to a value within a range in which the circumferential position of the ball 4 can be maintained by the pocket portion 3a when the projection 7f and the flat surface 3f are engaged with each other. Also, the clearance c is set to be sufficiently larger than 1.5 μm in order to realize the fluid lubrication state described above.

The ball bearing 10 is as described above, with a locking member attached to the outer race 1 as either one of the outer race 1 and the inner race 2. 7, and the engaging member 7 has a facing portion 7e arranged in the other axial direction with respect to the retainer 3 so as to restrict movement of the retainer 3 in the other axial direction. The movement in the other direction can be restricted by the engagement between the retainer 3 and the facing portion 7e of the locking member 7. As shown in FIG. Therefore, it is possible to set the relationship between the axial depth H of the pocket portion 3a, which is open on one axial side surface of the retainer 3, and the diameter d of the balls 4 to H≦0.65d. is. Since the ball bearing 10 is set to H≤0.65d, the projecting portion for forming the pocket portion 3a is shortened to reduce weight, suppress deformation of the retainer 3 due to centrifugal force, and reduce the weight of the pocket portion. Shear resistance between 3a and ball 4 can be suppressed. Further, since the ball bearing 10 is set to 0.15d≦H, the original function of the retainer 3 to keep the circumferential positions of the balls 4 in the pocket portion 3a can be ensured.

Further, in the ball bearing 10, the outer bearing ring 1 as one bearing ring is continuous in the circumferential direction with depth in the radial direction at the other position in the axial direction than the raceway surface 1a of the bearing ring 1. It has a seal groove portion 1b, and the engaging member 7 is formed of a metal plate-made core metal 7a and an elastomer 7b attached to the core metal 7a, and consists of a seal attached to the seal groove portion 1b. One bearing ring 1 and locking member 7 can be realized based on the specifications of the bearing ring and seal for a sealed ball bearing, thereby suppressing an increase in cost. In addition, since the locking member 7 is only arranged on the other side of the retainer 3 in the axial direction, there is no effect on the layout in the axial direction of a general sealed deep groove ball bearing, and the assembly line and assembly process of the ball bearing 10 are not affected. , can be the same as a ball bearing with a conventional crown cage.

Since the ball bearing 10 employs a locking member 7 that also serves as a seal, the locking member 7 is used to prevent excessive inflow of lubricating oil from the outside of the bearing into the bearing. It is also possible to reduce the rotational torque of the ball bearing 10 and prevent heat generation during normal operation by suppressing the agitation resistance of the ball bearing 10 .

In particular, since the ball bearing 10 is set to H<0.5d, deformation of the retainer 3 due to centrifugal force and the aforementioned shear resistance can be further suppressed. dimensional accuracy is improved.

Further, since the ball bearing 10 is set to H<0.5d, it does not have claws like a conventional crown-shaped retainer. Balls 4 are not pushed into the pocket part 3a, and only the holder 3 is placed at a predetermined position on the plurality of balls 4 arranged between the bearing rings 1 and 2, so that the pocket part 3a can be easily charged with balls. Once the retaining member 7 is press-fitted into the seal groove portion 1b and attached to the outer bearing ring 1, the retainer 3 placed at the predetermined position cannot be removed any more. For these reasons, the ball bearing 10 can be easily assembled.

Further, in the ball bearing 10, an axial clearance c is set between the locking member 7 and the cage 3, and either the facing portion 7e of the locking member 7 or the cage 3 is used as the facing portion. 7e has two or more projections 7f forming a circumferentially axially narrowing space between it and the cage 3 on the other hand, the projections 7f being circumferentially spaced apart. Since they are arranged side by side, the lubricating oil enters between the facing portion 7e of the locking member 7 and the two opposing side surfaces of the retainer 3, and the wedge-shaped space formed between the projection 7f and the retainer 3 is filled. Dragging the lubricant in the narrowing direction creates a wedge effect. Therefore, the ball bearing 10 promotes the formation of an oil film between the two opposing side surfaces of the opposing portion 7e and the retainer 3, and can prevent wear of the retainer 3 and the opposing portion 7e.

In particular, when the circumferential speed difference between the retainer 3 and the locking member 7 exceeds a predetermined value, the projections 7f arranged at intervals in the circumferential direction rotate at high speed and drag the lubricating oil. At 3f, the oil film is kept continuous in the circumferential direction, the wedge effect is continuously generated, the friction state between the retainer 3 and the locking member 7 becomes a fluid lubrication state, and the opposing portion 7e and the retainer 3 The movement of the retainer 3 in the other axial direction is restricted by the non-contact engagement via the oil film. Therefore, the ball bearing 10 can satisfactorily prevent the aforementioned wear even during high-speed rotation.

Further, in the ball bearing 10, the opposing portion 7e of the locking member 7 has projections 7f, and these projections 7f are formed of the elastomer 7b. The dimensional accuracy of the projections 7f can be improved more than when the projections are press-worked on the core bar.

Moreover, since the retainer 3 of the ball bearing 10 is made of engineering plastics, the use of expensive super engineering plastics can be avoided, and the manufacturing cost of the retainer can be suppressed.

In the first embodiment, the locking member 7 based on the specification of a general non-contact type seal is used, but it is also possible to use a locking member based on the specification of a contact type seal. A second embodiment as an example thereof is shown in FIGS. 8 to 11. FIG. In addition, below, it stops at describing a difference with 1st embodiment.

As shown in FIG. 8, an inner bearing ring 20 as the other bearing ring opposite to one bearing ring 1 has a seal sliding surface 20a extending along the entire circumference along the circumferential direction. The seal sliding surface 20a is located on the other side in the axial direction of the inner raceway surface 2a and is formed into a cylindrical surface that continues to the chamfered outer circumference of the inner raceway ring 2 on the other side in the axial direction.

The locking member 21 has a seal lip 21a formed to be slidable in the circumferential direction with respect to the seal sliding surface 20a. An interference is set between the seal lip 21a and the seal sliding surface 20a.

As shown in FIGS. 9 and 10, the seal lip 21a has two or more elastic projections 21b which form a wedge-shaped space which narrows axially in the circumferential direction between the seal lip 21a and the seal sliding surface 20a. include. These elastic protrusions 21b extend in a direction perpendicular to the circumferential direction and are arranged at intervals in the circumferential direction. FIG. 10 shows the state of the elastic projection 21b in its natural state (corresponding to the transferred shape at the time of molding). In the state shown in the figure, the elastic projection 21b extends straight in the radial direction. As shown in FIG. 9, the height of the elastic projection 21b gradually decreases toward the tip end of the seal lip 21a. As shown in FIGS. 9 and 11, the elastic projections 21b adjacent in the circumferential direction form oil passages that communicate between the inside and outside of the bearing. Only these elastic protrusions 21b of the locking member 21 are slidable in the circumferential direction with respect to the inner bearing ring 20. As shown in FIG.

As shown in FIG. 11, the elastic protrusion 21b forms a wedge-shaped space with the seal sliding surface 20a that narrows in the axial direction in the circumferential direction. The aforementioned wedge shape is defined based on the wedge angle formed by the tangent to the elastic projection 21b and the seal sliding surface 20a in the cross-sectional view of FIG. The elastic projection 21b has a semicircular shape in any cross section along the circumferential direction. Therefore, the wedge angle becomes smaller as it gets closer to the tip of the elastic projection 21b (the highest position in the axial direction in the elastic projection 21b). With such a shape of the elastic projection 21b that gradually decreases the wedge angle, the elastic projection 21b does not have a sharp tip toward the seal sliding surface 20a. Therefore, when the ball bearing rotates at high speed, even if the tip of the elastic projection 21b is pressed against the oil film by the straining force of the seal lip 21a, it is possible to prevent the oil film from running out. In addition, the area of sliding contact, which greatly affects seal torque, is reduced. The seal specifications for fluid lubrication such as the seal lip 21a are disclosed in Japanese Patent Application No. 2016-044050.

As the bearing rotates, the elastic protrusions 21b of the seal lip 21a drag the lubricating oil in the oil passage toward the seal sliding surface 20a toward the narrow wedge-shaped space. Formation is promoted. When the circumferential speed difference between the locking member 21 and the inner raceway ring 20 exceeds a predetermined value, the number of passages of the elastic projection 21b per rotation increases, and the oil film continues over the entire circumference of the seal sliding surface 20a. The wedge effect between the elastic protrusions 21b is continuously generated, and the friction state between the seal lip 21a and the seal sliding surface 20a becomes a fluid lubrication state. Therefore, the ball bearing according to the second embodiment can suppress wear of the seal lip 21a, reduce seal torque to the same level as the first embodiment, and can cope with high-speed rotation of the ball bearing. In addition, since heat generation during high-speed rotation is suppressed by reducing the seal torque, pressure fluctuations inside the bearing are also suppressed, and adsorption of the seal lip 21a to the seal sliding surface 20a is also prevented.

Further, in the ball bearing according to the second embodiment, the particle size of foreign matter that can pass through the oil passage between the elastic projections 21b adjacent in the circumferential direction can be determined based on the projection height of the elastic projections 21b. , it is also possible to prevent foreign matter of a predetermined particle size from entering.

In each of the above-described embodiments, an example in which the locking member is attached to the outer bearing ring was shown, but the locking member may be attached to the inner bearing ring.

Further, in each embodiment, an example in which projections are formed on the facing portion of the locking member is shown, but two or more projections are formed on the other side surface of the retainer in the axial direction, and the facing portion of the locking member is circular. It may also form an annulus. In this case, if the annular surface of the opposing portion is made of elastomer, the induced thrust force will bite the protrusions of the retainer, increasing the seal torque.

In addition, in each of the embodiments, as an attachment structure of the locking member, the base end portion of the locking member and the seal groove portion have a general form, but in this case, the base end portion is mounted against the induced thrust load. If they cannot be fixed, they can be modified into specially designed forms that can resist induced thrust forces and restrict cage movement. That is, if the generation of the radial component force that pushes the base end portion of the locking member toward the other bearing ring (the inner bearing ring 2) on the other side in the axial direction of the seal groove portion that receives the induced thrust load is suppressed, It is possible to make the end difficult to come off from the seal groove. For example, the contact surface between the other side of the seal groove in the axial direction and the base end portion of the locking member is preferably a surface with an inclination angle of 10° or less toward the other bearing ring in the radial direction toward the other side of the axial direction. . In this case, in order to improve the discharge of shavings when grinding the seal groove portion with a rotary grindstone, one side of the seal groove portion in the axial direction has an inclination angle toward the other bearing ring in the radial direction. , and this inclination angle should be set larger than the above-mentioned inclination angle of the contact surface.

Moreover, in each embodiment, although the ball bearing provided with only one retainer was illustrated, you may provide two retainers. In this case, cages are arranged on both sides of the balls. Since the bearing ring 1 has seal grooves 1b on both sides, it is also possible to attach two locking members for regulating each retainer. In order to accommodate the balls in the pocket portions of the two cages, the depth H of the pocket portions should be made smaller than 0.5d so that the cages on both sides of the balls do not abut each other in the axial direction. good.

In addition, in each embodiment, a standard bearing ring for a deep groove ball bearing is illustrated in which the shoulders on both sides of the raceway surface are at the same height. can be changed to

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. Therefore, the scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and scope of equivalents of the scope of the claims.

1 Outer ring (one ring)
1a Outer raceway surface 1b Seal grooves 2, 20 Inner bearing ring (other bearing ring)
2a Inner raceway surface 3 Cage 3a Pocket portion 4 Balls 7, 21 Locking member 7a Core metal 7b Elastomers 7d, 21a Seal lip 7e Opposed portion 7f Projection 10 Ball bearing 20a Seal sliding surface 21b Elastic projection

Claims (4)

an outer raceway ring having an outer raceway surface; an inner raceway ring having an inner raceway surface; a ball and a resin retainer for evenly arranging the plurality of balls in a circumferential direction,
The retainer has pocket portions at a plurality of locations in the circumferential direction for maintaining the circumferential positions of the balls,
In a ball bearing in which the pocket portion is open on one side surface in the axial direction of the retainer,
further comprising a locking member attached to one of the outer bearing ring and the inner bearing ring,
the locking member has a facing portion disposed on the other axial side with respect to the retainer so as to restrict the movement of the retainer in the other axial direction;
When the axial depth of the pocket portion is H and the diameter of the ball is d, the relationship between H and d is set to 0.15d≦H≦0.65d,
one of the bearing rings has a seal groove portion that is radially deep at a position on the other side in the axial direction relative to the raceway surface of the bearing ring and that continues along the entire circumference in the circumferential direction;
the locking member is formed of a metal plate-made core and an elastomer attached to the core, and comprises a seal attached to the seal groove,
an axial clearance is set between the locking member and the retainer;
Either one of the facing portion of the locking member and the retainer has two or more projections forming a space between the other and the other that narrows in the axial direction in the circumferential direction, The protrusions are arranged so as to be spaced apart in the circumferential direction,
The core metal includes an annular plate portion extending along the entire circumference along the radial direction and the circumferential direction, a base end portion of the annular plate portion bent in one axial direction from the seal groove portion side, and the annular plate. and a tip portion bent in one axial direction from the opposite side of the bearing ring of the portion,
The locking member includes a seal lip formed by the elastomer so as to extend from the bonding surface of the core bar to the opposite side of the bearing ring, and the elastomer to enclose the base end of the core bar. and a base end portion held in the seal groove portion formed as
The facing portion of the locking member has the two or more projections, and these projections connect the base end portion of the locking member and the seal lip and extend in the axial direction of the annular plate portion of the core bar. A ball bearing characterized in that it is formed by the elastomer covering one side surface . 2. The ball bearing according to claim 1, wherein the relationship between the depth H of said pocket portion and the diameter d of said ball is set to H<0.5d. Of the outer bearing ring and the inner bearing ring, the one bearing ring and the other bearing ring opposite to the one bearing ring have a seal sliding surface that extends along the entire circumference along the circumferential direction,
The locking member has a seal lip formed by the elastomer so as to be circumferentially slidable against the seal sliding surface, and the seal lip is circularly disposed between the seal sliding surface and the seal sliding surface. two or more elastic projections forming spaces that narrow axially in the circumferential direction, the elastic projections being spaced apart in the circumferential direction and between circumferentially adjacent elastic projections 3. The ball bearing according to claim 1 or 2, wherein is an oil passage communicating between the inside of the bearing and the outside of the bearing. 4. A ball bearing according to any one of claims 1 to 3 , wherein said retainer is made of engineering plastic.

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