WO2023189431A1

WO2023189431A1 - Ball bearing

Info

Publication number: WO2023189431A1
Application number: PCT/JP2023/009355
Authority: WO
Inventors: 紘哉磯▲崎▼; 孝康田窪
Original assignee: Ntn株式会社
Priority date: 2022-03-28
Filing date: 2023-03-10
Publication date: 2023-10-05
Also published as: JP2023144210A

Abstract

Provided is a ball bearing using a crown type retainer, which has good lubrication performance, and a reduced contact surface pressure between an inner surface of a pocket and a ball, and is capable of further reducing a rotational torque. This ball bearing has a pocket 31 of a retainer 24 for storing a ball 23, the pocket 31 being formed by an annular base part 30, a recessed part 31a provided in the base part 30, and a pair of retaining claws 32 disposed on an opening rim of the recessed part 31a so as to be spaced apart from and face each other. Each of the retaining claws 32 is formed by an outer diameter-side claw part 34 and an inner diameter-side claw part 35 separated on the inner-diameter side and the outer-diameter side with a slit 33 therebetween.

Description

ball bearing

This invention eliminates the lack of lubricating oil in the pockets of a cage that houses balls, which are rolling elements, during high-speed rotation, and prevents heat generation and damage caused by interference between the cage and balls. Regarding ball bearings that can be applied to parts, industrial machinery, and all other high-speed rotation applications.

Generally, as shown in FIG. 10, a ball bearing includes an inner raceway member 1 having an inner raceway groove 1a formed on its outer periphery, an outer raceway member 2 having an outer raceway groove 2a formed on its inner periphery, and an inner raceway member 2 having an outer raceway groove 2a formed on its inner periphery. It includes a plurality of balls 3 interposed between the groove 1a and the outer raceway groove 2a, and a retainer 4 that holds the balls 3 at regular intervals.

As the retainer 4, a crown-shaped retainer 4 as shown in FIG. 11 may be used.

The crown-shaped retainer 4 includes an annular base portion 4a and a plurality of pockets 5 provided on one axial end surface of the base portion 4a to rotatably hold balls 3, which are rolling elements.
Each pocket 5 is formed of a recess 5a provided on one end surface in the axial direction of the base portion 4a, and a pair of holding claws 5b disposed opposite to each other at an interval at the opening edge of the recess 5a. The mutually opposing surfaces of the pair of holding claws 5b and the inner surface of the recess 5a continuously form one spherical concave surface.

By the way, in electric vehicles, in order to improve electricity consumption and driving performance, it is necessary to increase the rotational speed of the electric motor and make the electric motor smaller and lighter. As the electric motor rotates at higher speeds, the maximum rotational speed of the bearing used increases, and the centrifugal force acting on the internal components of the bearing increases.

When a crown-shaped cage 4 is used as a cage for such a ball bearing for high-speed rotation applications, the resistance gradually increases due to interference with the balls 3 due to deformation of the pair of holding claws 5b due to centrifugal force. In addition to the problem of heat generation, the problem of wear of the holding claws 5b and balls 3 occurs.

Patent Document 1 discloses a ball bearing in which the balls do not come into contact with the inner circumferential end of the pocket portion that accommodates the balls even if the cage is deformed by centrifugal force.

That is, in the ball bearing of Patent Document 1, as shown in FIGS. 12 and 13, the holding pawl 4b is formed into a straight column shape extending in the axial direction, so that even if the column-shaped holding pawl 4b is deformed by centrifugal force. , the ball 3 is prevented from interfering with the inner peripheral side end of the pocket that accommodates the ball 3.

Patent No. 6866564

However, in the ball bearing disclosed in Patent Document 1, a guide portion 4d for positioning the cage 4 by contacting the inner raceway groove 1a is provided on the inner diameter side of the column-shaped holding claw 4b, and the guide portion 4d of the cage 4 and the inner raceway groove 1a are brought into contact with each other. When the guide portion 4d of the retainer 4 and the inner raceway groove 1a come into contact with each other, the oil film of the inner raceway groove 1a may run out or friction may occur, leading to concerns about deterioration of the lubrication state. Further, since a sufficient distance and clearance between the retainer 4 and the inner raceway groove 1a cannot be ensured, there is a concern that oil permeability may deteriorate.

In view of this, the present invention aims to improve the lubrication performance by making it difficult for the oil film in the raceway groove to run out and friction to occur, while also making it easier for the lubricating oil to flow into the pocket that accommodates the balls, and the contact surface between the inner surface of the pocket and the balls. The present invention aims to provide a ball bearing using a crown-shaped retainer that can reduce pressure and further reduce rotational torque.

In order to solve the above problems, a ball bearing according to the present invention includes an inner raceway member having an inner raceway groove formed on its outer periphery, an outer raceway member having an outer raceway groove formed on its inner periphery, and an inner raceway member having an outer raceway groove formed on its inner periphery. The cage includes a plurality of balls interposed between the groove and the outer raceway groove, and a cage that holds the balls at regular intervals, and the cage includes an annular base portion and an axially aligned portion of the base portion. A plurality of pockets are provided on the end surface and hold the balls in a rollable manner, and each pocket is arranged opposite to a recess provided on one end surface in the axial direction of the base portion and an opening edge of the recess at a distance from each other. A ball bearing is formed from a pair of disposed retaining claws, and the mutually opposing surfaces of the pair of retaining claws and the inner surface of the recess continuously form one spherical concave surface, wherein each of the retaining claws is It is characterized by comprising an outer diameter side claw part and an inner diameter side claw part which are divided into an outer diameter side and an inner diameter side with a slit part in between.

It is preferable that the radial thickness of the outer diameter side claw portion is formed to be thicker than the radial thickness of the inner diameter side claw portion.

It is desirable that the edges of the outer diameter side claw portion and the inner diameter side claw portion on the slit portion side of the inner surface of the pocket that accommodates the ball be formed into an R shape.

Further, it is desirable that the pitch circle diameter of the pocket of the cage is set smaller than the pitch circle diameter of the balls stored in the pocket.

As described above, in the cage used for the ball bearing according to the present invention, the retaining claws forming the pocket portion for storing the balls are divided into the outer diameter side and the inner diameter side with the slit portion in between, so that the retainer is inside the pocket portion. This makes it easier for lubricating oil to flow into the tank. Further, since the lubricating oil can be held in the slit portion, even under dilute lubrication conditions, the lubricating oil held in the slit portion is supplied, so that poor lubrication between the retainer and the balls is less likely to occur.

In addition, by dividing the holding claw into an outer diameter side and an inner diameter side with a slit in between, it is possible to have multiple contact points between the balls and the cage, so the contact surface pressure between the balls and the cage can be increased. is dispersed and reduced, and heat generation and damage caused by interference between the retaining claw and the ball that occur during high-speed rotation can be prevented.

In addition, by making the outer diameter side claw part and the inner diameter side claw part thicker in the radial direction than the inner diameter side claw part, it is possible to lubricate the inside of the pocket part of the cage. It becomes easier for oil to flow in, the contact surface pressure between the inner surface of the pocket and the ball is reduced, and the rotational torque can be further reduced.

Furthermore, by making the pitch diameter of the pocket smaller than the pitch diameter of the ball, the effect of supplying the lubricating oil held in the slit portion is further improved.

Furthermore, by forming the edges of the outer and inner claws on the slit side of the inner surface of the pocket that accommodates the balls into an R shape, the lubricating oil on the ball surface is prevented from being scraped off. , the contact condition between the cage and balls is improved, and wear and heat generation of the cage and balls can be prevented.

Furthermore, compared to conventional cages, the mass of the cage is reduced by the slit portion, so centrifugal force during high-speed rotation can be reduced and costs can be reduced.

FIG. 1 is a longitudinal cross-sectional view of a ball bearing according to the present invention. FIG. 2 is a perspective view of a cage used in the ball bearing of FIG. 1; FIG. 3 is a partially enlarged view of the retainer in FIG. 2; FIG. 3 is an enlarged view showing an embodiment in which the edges of the outer diameter claw portion and the inner diameter claw portion on the slit portion side of the inner surface of the pocket that accommodates the balls are formed into an R shape. FIG. 3 is an enlarged view showing an embodiment in which the edges of the outer diameter claw portion and the inner diameter claw portion on the slit portion side of the inner surface of the pocket that accommodates the balls are not rounded. FIG. 7 is a partially enlarged view showing an embodiment in which the opposing curved surfaces of the holding claw are shaped like a Gothic arch having multiple curved surfaces. It is a partially enlarged view showing an embodiment in which the pocket PCD is smaller than the ball PCD. FIG. 3 is a plan view of the retainer in FIG. 2 viewed from the retaining claw side. FIG. 9 is a side view of the cage shown in FIG. 2 taken along line AA in FIG. 8; FIG. 2 is a longitudinal cross-sectional view of a conventional ball bearing. 11 is a perspective view of a cage used in the ball bearing of FIG. 10. FIG. FIG. 3 is a vertical cross-sectional view of another conventional ball bearing. 13 is a partially enlarged perspective view of a cage used in the ball bearing of FIG. 12. FIG.

Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

FIG. 1 shows a ball bearing 20 according to an embodiment of the present invention. Used in alternators, idler pulleys, electromagnetic clutches for car air conditioners, electric fan motors, etc.

The ball bearing 20 according to the embodiment shown in FIG. 1 includes an inner raceway member 21 having an inner raceway groove 21a formed on the outer circumferential surface, and an outer raceway groove 22a disposed on the outside of the inner raceway member 21, and an outer raceway groove 22a on the inner circumferential surface. The formed outer raceway member 22, a plurality of balls 23 rotatably interposed between the inner raceway groove 21a of the inner raceway member 21 and the outer raceway groove 22a of the outer raceway member 22, and the inner raceway member 21. A retainer 24 is arranged between the inner race member 21 and the outer race member 22 and holds the balls 23 at equal intervals in the circumferential direction; The main part is constituted by a seal member 26 that seals an annular space 25 formed between the member 21 and the outer raceway member 22. By filling the annular space 25 sealed by the seal member 26 with lubricating oil such as grease, the balls 23 can roll smoothly within the pockets of the retainer 24.

In this embodiment, the outer raceway member 22 is attached to a stationary member such as a housing, and the inner raceway member 21 is attached to an electric motor or a rotating shaft rotationally driven by engine output. The seal member 26 is composed of an annular core metal 26a and a rubber-like member 26b that is integrally fixed to the core metal 26a. Fixed in mated state. In the inner raceway member 21, a seal groove 28 consisting of a circumferential groove is formed at a position corresponding to the inner circumference of the seal member 26, and a seal lip 26c formed at the inner circumference side end of the seal member 26 is formed at a position corresponding to the inner circumference of the seal member 26. It is in sliding contact with the seal groove 28 of 21. Although this embodiment illustrates a type in which the inner raceway member 21 rotates, a type in which the inner raceway member 21 is attached to a stationary member such as a shaft and the outer raceway member 22 is attached to a rotating shaft and rotates may also be used. is also applicable.

During operation of the ball bearing 20, the inner raceway member 21 rotates while the seal lip 26c at the tip of the seal member 26 remains in sliding contact with the outer peripheral end of the inner raceway member 21. This prevents foreign matter such as water and dust from entering the bearing, or lubricant from leaking from the inside of the bearing to the outside.

As shown in FIGS. 2 and 3, the cage 24 includes an annular base portion 30 and a plurality of cages provided on one end surface of the base portion 30 in the axial direction to rotatably hold balls 23, which are rolling elements. It has 31 pockets.

Each pocket 31 is formed of a recess 31a provided on one end surface in the axial direction of the base portion 30, and a pair of holding claws 32 disposed opposite to each other at an interval at the opening edge of the recess 31a. The mutually opposing surfaces of the pair of holding claws 32 and the inner surface of the recess 31a continuously form one spherical concave surface.

The holding claw 32 is composed of an outer diameter claw portion 34 and an inner diameter claw portion 35, which are divided into an outer diameter side and an inner diameter side with the slit portion 33 in between.

In this way, by dividing the holding claw 32 into the outer diameter side and the inner diameter side with the slit portion 33 in between, it is possible to have multiple contact points between the balls 23 and the retainer 24. The contact surface pressure between them is dispersed and reduced, and it is possible to prevent heat generation and damage caused by interference between the holding claws 32 and balls 23 that occur during high-speed rotation.

The radial wall thickness of the outer diameter side claw part 34 and the inner diameter side claw part 35 is such that the outer diameter side claw part 34 is thicker than the inner diameter side claw part 35. This facilitates the flow of lubricating oil into the pockets 31 of the retainer 24, reduces the contact surface pressure between the inner surface of the pockets 31 and the balls 23, and further reduces the rotational torque.

Further, the radial width of the slit portion 33 is preferably 40% or less of the radial width of the retainer 24 in order to maintain the strength of the outer diameter claw portion 34 and the inner diameter claw portion 35.

When the edges of the outer diameter side claw part 34 and the inner diameter side claw part 35 on the inner surface of the pocket 31 on the slit part 33 side are formed into an R shape as shown by the dot-dashed circle in FIG. 4, as shown in FIG. 5. Compared to the case where the R shape is not formed, it is possible to prevent the lubricating oil from being scraped off by the edges of the outer diameter side claw part 34 and the inner diameter side claw part 35, and to set the contact point of the ball 23 and the holding claw 32 to the slit part 33. Since it can move from the edge into the plane of the outer diameter side claw part 34 and the inner diameter side claw part 35, the lubrication performance is improved.

The shape of the opposing curved surfaces of the holding claws 32 is not a single curved surface shape in which all the center dimensions of the curved surfaces are the same, but may be a Gothic arch shape with multiple curved surfaces having multiple centers as shown in FIG. good. For example, the centers of the curved surfaces of the outer diameter claw portion 34 and the inner diameter claw portion 35 may be different. By making the opposing curved surfaces of the holding claw 32 into a gothic arch shape with multiple curved surfaces, the contact points between the balls 23 and the holding claws 32 are increased, so the contact surface pressure between the balls 23 and the holding claws 32 is dispersed. - It is possible to more effectively prevent heat generation and damage due to interference between the holding claws 32 and the balls 23 that occur during high-speed rotation. In FIG. 6, the x mark indicates the contact point between the ball 23 and the holding claw 32.

Next, the pitch circle diameter (pocket P.C.D.) of the pocket 31 of the retainer 24 and the pitch circle diameter (ball P.C.D.) of the balls 23 may be the same, but as shown in FIG. , the pocket P.C.D. of the retainer 24 may be smaller than the ball P.C.D. By making the pocket P.C.D. of the retainer 24 smaller than the ball P.C.D., the balls 23 are guided by the outer diameter side pawl portion 34 during non-high speed operation, and the holding pawls are guided during high speed rotation. 32 is deformed, by guiding the ball 23 by the inner diameter side claw portion 35, it is possible to prevent an increase in rotational torque due to interference between the holding claw 32 and the ball 23.

As shown in FIG. 7, the radial width w1 of the outer diameter claw portion 34 and the radial width w2 of the inner diameter claw portion 35 are larger than the radial width w1 of the outer diameter claw portion 34 to which centrifugal force is applied more. It is preferable to increase the strength by making the width wider than the radial width w2 of the inner claw portion 35.

Further, the radial width w3 of the slit portion 33 between the outer diameter side claw portion 34 and the inner diameter side claw portion 35 is set so that the retainer 24 is preferably 40% or less of the radial width w.

Furthermore, it is preferable that the minimum width in the radial direction of the slit portion 33 be at least one half of the radial width w2 of the inner claw portion 35. If the minimum width in the radial direction of the slit portion 33 is less than half of the radial width w2 of the inner claw portion 35, the radial width of the slit portion 33 will be too narrow and the lubricating oil will not flow (inflow). (sexuality) etc.

In addition, from the viewpoint of formability, the radial upper end surface of the slit portion 33 may be located below the center line of the radial width w of the retainer 24, or the radial lower end surface of the slit portion 33 may be located below the center line of the radial width w of the retainer 24. , the center line of the radial width w of the retainer 24 may be located within the radial width of the slit portion 33 without being located above the center line of the radial width w of the retainer 24. preferable.

In order to reduce the weight of the retainer 24, the depth of the slit portion 24d (h shown in FIG. It is desirable to make the distance deeper than the center of the pocket 31, as shown in FIGS. 3 and 9.

As described above, the retainer 24 used in the ball bearing 20 according to the present invention has the slit portion 33 between the outer diameter claw portion 34 and the inner diameter claw portion 35. It is possible to reduce the weight of the cage 24 compared to one without it, and the center of gravity of the cage 24 can be moved toward the back side, so that the eccentricity of the cage 24 can be lowered. Thereby, when centrifugal force acts on the holding claws 32 during high-speed rotation, the moment applied to the holding claws 32 can be reduced, and the amount of deformation of the holding claws 32 can be reduced.

Furthermore, by reducing the weight of the retainer 24, it is possible to reduce centrifugal force during high-speed rotation and reduce costs.

As the material for the retainer 24, a resin with excellent wear resistance and seizure resistance can be used, and in particular, a resin with excellent tensile elongation, tensile strength, impact resistance, abrasion resistance, lubricity, etc. Polyamide resins such as PA66 (polyamide 66), PA46 (polyamide 46), PA9T (polyamide 9T), PA11 (polyamide 11) or PA6 (polyamide 6) are desirable.

Furthermore, the inner raceway member 21, the outer raceway member 22, and the balls 23 are formed of metal such as bearing steel or carburized steel.

Furthermore, the grease filled in this ball bearing 20 is a semi-solid lubricant consisting of base oil, thickener, and additives. Examples of the base oil constituting the lubricating grease include mineral oils such as paraffinic mineral oil and naphthenic mineral oil, hydrocarbon synthetic oils such as polybutene, poly-α-olefin, alkylbenzene, alkylnaphthalene, and alicyclic compounds; Natural oils and fats, polyol ester oils, phosphate esters, diester oils, polyglycol oils, silicone oils, polyphenyl ether oils, alkyldiphenyl ether oils, non-hydrocarbon synthetic oils such as fluorinated oils, etc. are generally used as base oils for lubricating greases. Any conventional oil can be used without particular limitation.

Examples of thickeners include metal soap thickeners such as aluminum soap, lithium soap, sodium soap, composite lithium soap, composite calcium soap, and composite aluminum soap, and urea compounds such as diurea compounds and polyurea compounds. These thickeners may be used alone or in combination of two or more.

Known additives for lubricating greases include extreme pressure agents, amine-based and phenolic antioxidants, metal deactivators such as benzotriazole, viscosity index improvers such as polymethacrylate and polystyrene, and molybdenum disulfide. , solid lubricants such as graphite, etc. These can be added alone or in combination of two or more.

The retainer 24 used in the ball bearing 20 according to the present invention is of a type in which rotational motion is guided by balls 23 as rolling elements. Furthermore, the rotational motion may be either a so-called inner ring guide type in which the rotational motion is guided by the outer diameter surface of the inner raceway member 21 or a so-called outer ring guide type in which the rotational motion is guided by the inner diameter surface of the outer raceway member 22. It is desirable that the sliding portion of the outer raceway member 22 with the retainer 24 be ground.

As described above, in the ball bearing 20 according to the present invention, the holding claw 32 is divided into the outer diameter claw part 34 and the inner diameter claw part 35 with the slit part 33 in between, and lubricating oil can be retained in the slit part 33. , the weight can be reduced compared to the one without the slit part 33, and even in the ultra-high speed rotation region, lubricating oil can be retained and supplied well, the frictional resistance between the cage 24 and the balls 23 is eased, and the cage Heat generation and damage due to interference between the ball 24 and the ball 23 can be prevented, and rotational torque can be further reduced.

This invention is not limited to the embodiments described above, and it goes without saying that it can be implemented in various forms without departing from the gist of the invention. and includes the meaning of equivalents recited in the claims and all changes within that range.

20 Ball bearing 21 Inner raceway member 21a Inner raceway groove 22 Outer raceway member 22a Outer raceway groove 23 Balls 24 Cage 24d Slit portion 25 Annular space 26 Seal member 30 Base portion 31 Pocket 31a Recessed portion 32 Holding claw 33 Slit portion 34 Outer diameter side Claw portion 35 Inner diameter side claw portion

Claims

An inner raceway member having an inner raceway groove formed on its outer periphery, an outer raceway member having an outer raceway groove formed on its inner periphery, and a plurality of balls interposed between the inner raceway groove and the outer raceway groove. , a retainer that holds the balls at regular intervals, the retainer having an annular base portion and a plurality of pockets provided on one axial end surface of the base portion to rotatably hold the balls. Each pocket is formed of a recess provided in one end surface in the axial direction of the base portion, and a pair of holding claws arranged opposite to each other with a gap between them at the opening edge of the recess. A ball bearing in which the surfaces facing each other and the inner surface of the recess continuously form one spherical concave surface, and each of the retaining claws has an outer diameter side divided into an outer diameter side and an inner diameter side with a slit section in between. A ball bearing characterized by comprising a diameter side pawl portion and an inside diameter side pawl portion.
The ball bearing according to claim 1, wherein the radial thickness of the outer diameter side claw portion is formed to be thicker than the radial thickness of the inner diameter side claw portion.
The ball bearing according to claim 1 or 2, wherein the edges of the outer diameter claw portion and the inner diameter claw portion on the slit portion side of the inner surface of the pocket portion that accommodates the balls are formed into an R shape.
The ball bearing according to any one of claims 1 to 3, wherein the pitch circle diameter of the pocket of the retainer is set smaller than the pitch circle diameter of the balls stored in the pocket.
Any one of claims 1 to 4, wherein the rotational movement of the retainer is guided by an inner raceway member or an outer raceway member, and a sliding portion between the inner raceway member or the outer raceway member and the retainer is subjected to a grinding process. Ball bearings described in the above section.