WO2010119835A1

WO2010119835A1 - Deep groove ball bearing and method of designing same

Info

Publication number: WO2010119835A1
Application number: PCT/JP2010/056520
Authority: WO
Inventors: 藤原宏樹; 川村光生; 田口陽介
Original assignee: Ntn株式会社
Priority date: 2009-04-16
Filing date: 2010-04-12
Publication date: 2010-10-21

Abstract

Provided are a deep groove ball bearing which exhibits low torque characteristics and has a sufficient basic dynamic rated load, and a method of designing the deep groove ball bearing. The raceway grooves (2a, 3a) of inner and outer rings (2, 3), the heights (H_2a, H_3a) of groove shoulders, the diameter of balls, the number of the balls, and the pitch circle diameter of the balls are designed so as to satisfy the mathematical expression (9) with arbitrary values given to a and b which satisfy the relationship of a < b. 【９】S_i: The area of the clearance between the raceway groove of the inner ring and a ball in a radial cross-section of the bearing taken along an axial plane. S₀: The area of the clearance between the raceway surface of the outer ring and the ball in the radial cross-section. D_a: The diameter of the balls. d_m: The average of the inner and outer diameters of the bearing obtained by adding the outer diameter of the outer ring to the inner diameter of the inner ring and dividing the result by two. d_p: The pitch circle diameter of the balls. Z: The number of the balls.

Description

Deep groove ball bearing and design method thereof

Related applications

This application claims the priority of Japanese Patent Application No. 2009-099705 filed on Apr. 16, 2009 and Japanese Patent Application No. 2010-74327 filed on Mar. 29, 2010, which is incorporated herein by reference in its entirety. Cited as what constitutes

The present invention relates to a deep groove ball bearing and a design method thereof, and relates to a technique applied to the design of a deep groove ball bearing that supports rotating parts of various devices.

Among rolling bearings, deep groove ball bearings are the most widely used bearing types, and low torque and high torque are strongly required. In order to achieve this low torque, improvements have been made to the cage design, the grease composition for grease lubrication, and the seal design for a sealed type. Various inventions have also been made for the design of raceway raceway surfaces and balls (Patent Documents 1 and 2).

Many ball bearings are used in a state where grease is sealed as a lubricant and sealed with a seal or shield. Compared to lubrication with oil, a bearing using grease has advantages such as no need for lubrication facilities and maintenance-free operation.
The bearing has resistance to rotation, that is, rotational torque, and is affected by friction between the rolling elements and the inner and outer rings, friction between the rolling elements and the cage, stirring of the lubricant, and viscosity. In the case of grease lubrication, the torque of the bearing is a stirring resistance in which the balls and the cage stir the grease and a shear resistance in which the grease is sheared between the cage and the seal.

As a conventional technique for reducing the rotational torque in a grease-lubricated bearing, for example, a structure in which the rotational torque of the bearing becomes low even at low temperatures due to the composition of grease is disclosed (Patent Document 3).
As a conventional technique for reducing the torque of the bearing by the shape of the cage, for example, the cage is designed such that the minimum necessary lubricant is taken in between the inner peripheral surface of the cage pocket and the rolling surface of the ball. The thing which aimed at reduction of a sound and rotational torque is disclosed (patent document 4).
As a conventional technique for reducing the torque by other cages, for example, there is disclosed one in which a groove having a buffering action is provided between cage pockets when a rolling element collides with a pocket (Patent Document 5).
As a conventional technique for reducing the torque of other bearings, there is disclosed a technique in which the composition and shape of the bearing seal portion are changed (Patent Document 6).

JP 2003-74545 A US Pat. No. 6,647,792 Japanese Patent No. 3875108 Japanese Patent Laid-Open No. 10-238543 JP 2009-19766 A Japanese Patent No. 3772688

The inventions of

Patent Documents

1 and 2 are inventions that focus only on a part of the design parameters of the bearing raceway, and it is difficult to say that all parameters are considered. In general, when the bearing design is performed so that the torque is low, the basic dynamic load rating is reduced, and therefore the life is shortened. The “basic dynamic load rating” means that the direction and size are such that the basic rated life is 1 million revolutions when the same bearings are individually operated under the condition that the inner ring is rotated and the outer ring is stationary. A load that does not fluctuate. Radial bearings such as deep groove ball bearings take a radial load whose direction and size are constant.

In addition, according to the inventions of

Patent Documents

3 and 6, depending on the application of the bearing, there is a grease or seal that cannot be changed. Therefore, the use of the torque reduction method using grease or the seal is limited.
In the case of the invention of Patent Document 4, in a cage that takes in a minimum amount of lubricant between the inner peripheral surface of the cage pocket and the rolling surface of the ball, when a large amount of grease is sealed in the bearing space, the torque The effect of reduction cannot be obtained. In addition, since the area for holding the rolling elements is reduced in the cage, there is a possibility that the cage will swing and play.
According to the invention of Patent Document 5, in a cage in which a groove having a buffering action is provided between the cage pockets, torque reduction at the time of start-up or misalignment can be expected, but in a state where rotation is stable, The torque is the same as that of the cage.

A first object of the present invention is to provide a deep groove ball bearing capable of realizing a low torque and ensuring a sufficient basic dynamic load rating and a design method thereof.

A second object of the present invention is to reduce the torque during bearing operation without sacrificing rolling fatigue life and grease life in deep groove ball bearings used in grease lubrication, without being limited to bearing applications. It is to provide a deep groove ball bearing capable of

The deep groove ball bearing of the present invention is a deep groove ball bearing in which a ball is interposed between an inner ring and an outer ring, and the groove shoulder heights of the inner ring and the outer ring are each 0.2 times the diameter of the ball, and the inner and outer ring raceways The groove, groove shoulder height, ball diameter, the number of balls, and the pitch circle diameter of the balls are set within the following range.

The deep groove ball bearing may be lubricated with lubricating oil, grease, or solid lubricant. It may be provided with a cage that holds a plurality of balls interposed between the inner and outer rings.

According to this configuration, the area formed by the clearance between the inner ring raceway groove and the ball in the radial cross section viewed by cutting the bearing along the axial plane, and the outer ring raceway groove and the ball in the radial cross section. The area forming the clearance is set as a design parameter. If these areas are used as design parameters, the larger the area, the lower the torque.
Therefore, when (Si + So) / d _p D _a Z is large, the torque is low. This function depends on the size and diameter series of the bearing and is difficult to handle as it is. Therefore, each design parameter is made dimensionless as follows. The diameter series means a stepwise series of bearing outer diameters each having a bearing outer diameter with respect to a standard bearing inner diameter.

The inner and outer ring raceway grooves, groove shoulder height, ball diameter, number of balls, and balls so that the function f is larger than a certain value considering torque and smaller than an appropriate value considering basic dynamic load rating. If the pitch circle diameter is designed, a deep groove ball bearing with a low torque can be realized while having a sufficient basic dynamic load rating.

The groove shoulder heights of the inner ring and the outer ring are each 0.2 times the diameter of the ball, and a = 1 and b = 1.1. With this groove shoulder height, when a predetermined axial load is applied to the bearing, the contact ellipse between the ball and the race can be prevented from protruding from the race groove, and the bearing can be assembled. If the raceway groove curvature ratio of the inner and outer rings changes, the basic dynamic load rating changes. Here, the basic dynamic load rating is determined based on the theory of Lundberg-Palmgren (Non-Patent Document 1), which is the basis of this standard. In order to secure a basic dynamic load rating of 0.9 times or more than the basic dynamic load rating obtained by the same theory, the function f must be “1.1” or less. That is, by setting a = 1 and b = 1.1 and satisfying 1 <f <1.1, it is possible to design a low torque while ensuring a sufficient basic dynamic load rating.

In this invention, the deep groove ball bearing is a deep groove ball bearing in which the ball is held in a cage and lubricated by grease,
0.8d _m <d _P <d _m
The retainer has a crown shape that is partially open on one side surface of the annular body and has pockets for holding balls therein in a plurality of circumferential directions of the annular body, and the circumferential direction of the annular body A grease containing recess for storing grease is provided between the pockets adjacent to each other. The grease containing recess and the pocket communicate with each other, and the grease adhering to the ball is moved to the grease containing recess by the relative movement of the ball and the cage. A communication port is provided.

If _{_{_{0.8d m <d p <d m}}} , satisfying 1 <f <1.1. Therefore, it is possible to design a deep groove ball bearing capable of realizing a low torque and ensuring a sufficient basic dynamic load rating. In addition, the crown-shaped cage is provided with a grease-receiving recess, and a communication port that communicates with the grease-receiving recess and the pocket that holds the ball is provided. Move to. That is, when the ball rotates in the pocket, a part of the grease attached to the ball reaches the communication port, and further, the ball rotates in the pocket, so that a part of the grease is scraped by the edge of the communication port, for example. It moves by being pressed toward the grease-receiving recess through the communication port due to the take-off or ball pressure. Since the grease is stored in the grease containing recess and rotates together with the cage, the above-described stirring resistance and shear resistance can be reduced. In lubrication with grease, the base oil of grease acts on lubrication. Since the base oil separated from the grease held in the grease containing recess is supplied to the ball through the communication port, the base oil necessary for lubrication can be used.

When lubricated with grease, the grease is a grease composition in which an additive is blended with a base grease comprising a base oil and a thickener, and the additive comprises a plant-derived polyphenol compound and its decomposition. Containing at least one compound selected from the compounds, and the blending ratio of this compound is from 0.05 parts by weight to 10 parts by weight with respect to 100 parts by weight of the base grease, and the plant-derived polyphenol compound is curcumin or a derivative thereof And / or quercetin or a derivative thereof. In this case, the occurrence of peculiar peeling due to hydrogen embrittlement can be suppressed. Further, the oxidation deterioration resistance can be improved as compared with a grease composition containing a conventional antioxidant or the like, and the life of the bearing can be extended under high temperature and high speed.

The communication port may be a notch that allows the grease-receiving recess and the pocket to communicate with each other and that opens to the inner diameter side of the annular body. In this case, it is possible to enhance the effect of scraping off the grease at the edge of the notch, and to easily move the grease to the grease receiving recess. Further, the communication port can be provided without complicating the cage shape.

The angle of the central portion of the communication port with respect to the plane that is perpendicular to the axis of the annular body and passes through the center of the pocket may be in the range of 20 degrees to 50 degrees. When the cage is manufactured by injection molding, it is difficult to remove the cage from the mold if the angle of the central portion of the communication port with respect to the plane is as small as less than 20 degrees. Further, the contact portion between the balls and the inner and outer rings, that is, the raceway surface, has a small amount of grease attached. Therefore, if the angle is small, the effect of scraping the grease into the grease receiving recess is small. By making the angle in the range of 20 degrees or more and 50 degrees or less, it becomes easy to manufacture and the effect of scraping the grease into the grease receiving recess can be enhanced and the torque can be reduced.

The maximum width dimension along the circumferential direction of the cage of the pocket at the communication port may be in the range of 10% to 40% of the inner diameter of the pocket. If the maximum width dimension of the communication port is smaller than 10% of the inner diameter of the pocket, it becomes difficult to move the grease through the communication port. When the maximum width dimension of the communication port is larger than 40% of the inner diameter of the pocket, it becomes difficult for the pocket to hold the ball.

A cross-sectional shape of the annular body, where a portion where the grease containing recess is provided, is cut by a plane including the axial center of the annular body, and the inner wall portion of the annular body and a pocket adjacent in the circumferential direction are connected. The connecting portion forms the grease containing recess, the inner wall portion has an inclined surface inclined with respect to the axis, and the connecting portion has an inclined surface inclined with respect to a plane perpendicular to the axis. It is good also as what includes either or both of things.

When the inner wall portion has an inclined surface that is inclined with respect to the shaft center, the inner wall portion has an inclined surface that becomes thinner as it goes toward the anti-pocket side. The grease can be smoothly discharged from the inclined surface into the bearing space by centrifugal force due to rotation. On the contrary, if the inner wall portion has an inclined surface that becomes thicker toward the opposite pocket side, the grease accumulated in the grease receiving recess can be held so as not to leak out during the bearing operation.

When the connecting portion has an inclined surface that is inclined with respect to a plane perpendicular to the axis, if the connecting portion is an inclined surface that becomes thinner toward the inner diameter side, the rigidity of the cage is increased and high-speed rotation is achieved. In this case, the strength of the cage can be ensured. Further, during the bearing operation, the grease accumulated in the grease receiving recess can be smoothly discharged from the inclined surface into the bearing space through the inner wall portion by centrifugal force due to rotation. Conversely, if the connecting portion is an inclined surface that becomes thicker toward the inner diameter side, the grease accumulated in the grease-receiving recess can be held so as not to leak.

A partition plate may be provided in the grease containing recess. With this partition plate, the grease can be easily held in the grease containing recess.
You may provide the cover part which covers the other side surface of the non-pocket side of a grease accommodating recessed part among the said annular bodies. In the case of high-speed rotation, it is possible to prevent the grease held in the grease-receiving recess by the cover portion from leaking out.

You may provide a recessed part in the pocket opening edge of the annular body outer diameter side in the inner surface of the said pocket. The grease that has entered the pocket from the recess moves to the inner ring side and is leveled around the ball arrangement pitch circle. For this reason, it becomes possible to draw more grease in the bearing into the grease receiving recess.
You may provide a groove part in the bottom part of the inner surface of the said pocket. In this case, since part of the base oil separated from the grease enters the groove portion, the viscous shear resistance due to the base oil between the balls and the pockets can be reduced. Therefore, it can contribute to lower torque.

The retainer may be manufactured by injection molding, and the communication port may be provided so as to extend in parallel with the axis of the annular body or from the pocket side toward the grease containing recess. In this case, it is possible to easily remove the cage from the injection mold. In addition, a mold for forming a communication port can be applied to a mold on the side of a grease receiving recess that is relatively easy to process, not on the pocket side where high-precision processing is required for the mold. Therefore, the manufacturing cost of the mold can be reduced.

The grease containing recess may be initially filled with grease. The “initial stage” means a grease filling stage at the time of assembling the bearing. The grease moves to the grease-receiving recess in a very short time, resulting in low torque. For example, the grease should be initially sealed in the grease-receiving recess without changing the amount of grease itself sealed in the bearing space. Thus, the torque at the time of starting can be reduced.
Further, a sealing device that closes the bearing space between the inner and outer rings may be provided in the outer ring.

The design method of the deep groove ball bearing of the present invention is a design method of a deep groove ball bearing in which a ball is interposed between an inner ring and an outer ring, and an arbitrary value is set to a and b in the following formulas under the condition of a <b. Given this, the raceway groove, groove shoulder height, ball diameter, number of balls, and pitch circle diameter of the balls are designed to satisfy the following formula.

According to this configuration, a low torque deep groove ball bearing having a sufficient basic dynamic load rating can be realized.

The groove shoulder height of the inner ring and the outer ring may be 0.2 times the diameter of the ball, and a = 1 and b = 1.1. With this groove shoulder height, when a predetermined axial load is applied to the bearing, the contact ellipse between the ball and the race can be prevented from protruding from the race groove, and the bearing can be assembled.

The design may be realized by changing any variable of the function f, or two or more variables may be changed simultaneously. For example, by changing only the pitch circle diameter _{d p} of the ball is to be realized a low _torque, if _{_{0.8d m <d p <d m}} , satisfying 1 <f <1.1. Therefore, it is possible to design a deep groove ball bearing capable of realizing a low torque and ensuring a sufficient basic dynamic load rating.
The radial cross section is a cross section obtained by cutting a portion where a ball is brought into contact with the raceway groove of the inner and outer rings along the axial plane. In this case, the radial cross section can be uniquely obtained regardless of the radial clearance of the deep groove ball bearing.

The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in a plurality of drawings indicate the same or corresponding parts.
It is sectional drawing of the deep groove ball bearing which concerns on 1st Embodiment of this invention. It is a figure showing the relationship between a ball diameter and a torque. It is a figure showing the relationship between the number of balls and torque. It is a figure showing the relationship between the pitch circle diameter of a ball | bowl, and a torque. It is a figure showing the relationship between an inner ring groove curvature ratio and torque. It is a figure showing the relationship between an outer ring groove curvature ratio and torque. It is a figure showing the relationship between a deep groove ball bearing product number and the function f. It is sectional drawing of the deep groove ball bearing which concerns on 2nd Embodiment of this invention. It is an expanded sectional view of the same deep groove ball bearing. (A) is the perspective view which looked at the retainer of the deep groove ball bearing from the pocket side, (B) is the perspective view which looked at the retainer from the non-pocket side. It is sectional drawing of the principal part which cut | disconnected and extended | deployed the same holder | retainer by the cylindrical surface containing a pitch circle. It is sectional drawing seen by cut | disconnecting the location in which the grease accommodating recessed part was provided among the annular bodies of the holder | retainer by the plane containing the axial center of the annular body. It is sectional drawing of the principal part which cut | disconnected and extended | deployed the same holder | retainer by the cylindrical surface containing a pitch circle, and is sectional drawing explaining the position of a notch. It is sectional drawing of the principal part which cut | disconnected and extended | deployed the same holder | retainer by the cylindrical surface containing a pitch circle, and is sectional drawing explaining the magnitude | size of a notch. (A) is the side view seen from the non-pocket side of the cage after operating the same deep groove ball bearing, (B) is the side view seen from the pocket side of the cage after operating the same deep groove ball bearing. . (A) is a side view of the conventional deep groove ball bearing as a comparative example, viewed from the side opposite to the cage after operation, and (B) is viewed from the side of the cage after operation of the deep groove ball bearing. It is a side view. It is sectional drawing of the deep groove ball bearing which concerns on 3rd Embodiment of this invention. It is a figure which shows the relationship between the grease filling amount of a curcumin addition product and an additive-free product, and lifetime. (A) to (D) are cross-sectional views showing a cross-sectional shape of a grease receiving recess in a cage according to fourth to seventh embodiments of the present invention. It is a perspective view of the holder | retainer which concerns on 8th Embodiment of this invention. It is sectional drawing of the principal part of the holder | retainer which concerns on 9th Embodiment of this invention. It is a perspective view of the holder | retainer which concerns on 10th Embodiment of this invention. It is a perspective view of the holder | retainer based on 11th Embodiment of this invention. It is sectional drawing of the principal part which provided the partition plate in the grease accommodation recessed part of the holder | retainer based on 12th Embodiment of this invention. It is a perspective view of the conventional coronal cage. It is sectional drawing of the principal part of the crown-shaped cage.

A first embodiment of the present invention will be described with reference to FIGS. The deep groove ball bearing according to this embodiment supports, for example, rotating parts of various devices such as automobiles, electric motors, household electric appliances, instruments, internal combustion engines, construction machinery, railway vehicles, transporting machinery, agricultural machinery, industrial machinery, and robots. To be provided. This deep groove ball bearing can be loaded with a radial load, an axial load in both directions, and a combined load thereof.

As shown in FIG. 1, the deep groove ball bearing 1 has an inner ring 2, an outer ring 3, a plurality of balls 4, and a cage 5. A plurality of balls 4 are interposed between the

raceway grooves

2 a and 3 a of the inner and

outer rings

2 and 3, and the cage 5 holds these balls 4. The deep groove ball bearing 1 of this embodiment is shown as an open type without a seal member, but is not necessarily limited to this open type. For example, a non-contact type or a contact type sealing member that seals the bearing space may be provided on both side surfaces or one side surface. Lubricating oil, grease, solid lubricant, etc. are provided inside the bearing and contribute to lubrication. The cage 5 is made of, for example, two annular members manufactured by punching and forming a plate material made of an iron-based metal material, that is, a so-called iron plate by a press. The material of the cage 5 is not particularly limited only to the iron-based metal material, and a copper-based metal material, an aluminum-based metal material, a resin material, or the like can be used. Instead of the cage 5, a crown-shaped cage having pockets that are partially opened on one side surface of the annular body and hold the balls 4 inside is provided at a plurality of locations in the circumferential direction of the annular body. It is also possible. For example, steel balls or ceramic balls are used as the balls 4.

A design method of the deep groove ball bearing will be described. The main dimensions, that is, the inner diameter, outer diameter, width, and chamfer dimension of the deep groove ball bearing 1 are standardized by the International Organization for Standardization, abbreviated ISO. The main dimensions of deep groove ball bearings defined in Japanese Industrial Standard JIS B 1512 are also defined in accordance with this ISO. The shape of the raceway portion of the deep groove ball bearing 1 is as follows: the diameter D _{a of the} balls 4, the pitch circle diameter d _p , the diameters d _2a and d _3a (referred to as groove diameters) of the

race grooves

2a and 3a, the groove shoulder height H _2a , It can be determined by H _3a and the number of balls Z. The groove shoulder height H _2a in the inner ring 2 refers to the radial dimension from the bottom of the raceway groove that forms the smallest diameter of the raceway grooves 2a of the inner ring 2 to the outer diameter of the inner ring. The groove shoulder height H _3a in the outer ring 3 refers to the radial dimension from the bottom of the raceway groove forming the maximum diameter of the raceway groove 3a of the outer ring 3 to the inner diameter of the outer ring.

Here, it is considered that the friction torque between the ball 4 of the deep groove ball bearing 1 and the bearing ring is generated by the traction of the lubricating oil and the rolling viscous resistance. Considering the deep groove ball bearing 1 having an inner diameter of 30 mm, an outer diameter of 62 mm, and a width of 16 mm and having a bearing part number “6206”, the friction torque changes as shown in FIGS. This tendency does not change even in the case of solid contact where no lubricating oil is interposed between the balls 4 and the races.

That is, Qualitatively, the diameter D _a small ball 4, number of balls Z small, the pitch circle diameter d _p small, raceway groove curvature ratio of the inner ring 2 large, if the raceway groove curvature ratio is high the outer ring 3, a low torque It turns out that it becomes. The raceway groove curvature ratio of the inner ring 2, the radius of curvature of the arcuate section of the track groove 2a formed on the outer peripheral surface of the inner ring 2, divided by the diameter D _a of the ball 4, i.e. the inner ring 2 of the raceway groove curvature ratio = This is a value obtained by (the radius of curvature of the raceway groove 2a / the diameter D _{a of the} ball 4). The raceway groove curvature ratio of the outer ring 3 is a value obtained by dividing the radius of curvature of the raceway groove 3 a having a circular arc shape formed on the inner peripheral surface of the outer ring 3 by the radius D _a / 2 of the ball 4. The groove shoulder heights H _2a and H _3a are determined so that the contact ellipse between the ball 4 and the raceway does not protrude from the

raceway grooves

2a and 3a when a predetermined axial load is applied to the bearing. However, if the groove shoulder heights H _2a and H _3a are excessive, the bearing cannot be assembled. Groove shoulder height _H _2a, the ratio of the ball diameter _{D a} of _{H 3a} is about 0.2. As for the size of the

raceway grooves

2a and 3a, attention is paid to the clearance between the

raceway grooves

2a and 3a and the balls 4 in the radial cross section. As shown in FIG. 1, if the areas S _i and S _o forming the clearances between the

raceway grooves

2a and 3a of the inner and

outer rings

2 and 3 and the balls 4 in the radial cross section are set as design parameters, these areas Si and So The larger the value, the lower the torque. Therefore, when (S _i + S _o ) / d _p D _a Z is large, the torque is low. This function depends on the size and diameter series of the bearing and is difficult to handle as it is. Therefore, each design parameter is made dimensionless as follows. The radial cross section is a cross section obtained by cutting a portion where the balls 4 are brought into contact with the

raceway grooves

2a and 3a of the inner and

outer rings

2 and 3 along the axial plane.

Greater than a value in which the function f is considering torque, and to be less than the appropriate value in consideration of the basic dynamic load rating, raceway groove 2a of the inner and

outer rings

2,3, 3a, groove shoulder height H _2a, H _If the diameter D _{a of the} balls 4, the number of balls Z, and the pitch circle diameter d _p of the balls 4 are designed, a deep groove ball bearing having a low basic torque and a sufficient basic dynamic load rating can be realized.

The ratio of the groove shoulder heights H _2a and H _3a to the diameter D _a of the ball 4 is “0.2”, the raceway groove curvature ratio is “1.04” for both the inner and

outer rings

2 and 3, and the pitch circle diameter d _p is The average value of the inner and outer diameters of the bearing, that is, the inner ring inner diameter is added to the outer ring outer diameter and divided by 2. With respect to the function f, when the diameter D _a and the number of balls Z of the balls 4 are values of a general commercially available bearing, the function f is obtained as shown in FIG. The raceway groove curvature ratio varies depending on the manufacturer and product number, but in order to generalize and discuss, in this embodiment, it is used for calculation of the basic dynamic load rating defined in JIS B 1518 of the Japanese Industrial Standard. Value. In this case, 0.9 <f <1 is generally satisfied in a very general design. The larger the function f is, the lower the torque becomes. At the same time, the basic dynamic load rating decreases and the service life is shortened.

By the way, the calculation method of the basic dynamic load rating of the deep groove ball bearing is stipulated in Japanese Industrial Standard JIS B 1518. This means that the raceway groove curvature ratio of the inner and outer rings is “1.04”. Configured as a premise. However, since the basic dynamic load rating changes when the raceway groove curvature ratio of the inner and outer rings changes, the Lundberg-Palmgren theory (Non-Patent Document 1), which is the basis of this standard, is used here. Determine the basic dynamic load rating. That is, when the diameter D _a of the ball 4 is less deep groove ball bearing 25.4 mm, basic dynamic load rating C _r can be calculated by the following expression.

If we try to secure a basic load rating of 0.9 times or more than the basic dynamic load rating obtained under the design conditions considering the changes in the raceway groove curvature ratios mi and mo of the inner and

outer rings

2 and 3, the function f becomes Must be "1.1" or less. That is,
1 <f <1.1
By doing so, it is possible to design a deep groove ball bearing with low torque while ensuring a sufficient basic dynamic load rating. The design may be realized by changing any variable of the function f, or two or more variables may be changed simultaneously. For example, by changing only the pitch circle diameter _{d p} of the ball is to be realized a low _torque, if _{_{0.8d m <d p <d m}} , satisfying 1 <f <1.1. Therefore, it is possible to design a deep groove ball bearing capable of realizing a low torque and ensuring a sufficient basic dynamic load rating. 1 <When deep groove ball bearing which satisfies f <1.1, raceway groove curvature ratio of the inner and outer rings 2,3 m _i, even when the m _o while varying, ensure sufficient basic dynamic load rating In addition, it is possible to obtain a deep groove ball bearing with reduced torque.

A second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 8, the deep groove ball bearing 1 according to this embodiment is not an open-type deep groove ball bearing as in the first embodiment but a sealed deep groove ball bearing, and is the same as the first embodiment. Corresponding portions are denoted by the same reference numerals, and detailed description thereof is omitted. The deep groove ball bearing 1 </ b> A of the second embodiment is different from the first embodiment in a closed type deep groove ball bearing and has sealing

devices

6 and 6 that close the bearing space between the inner and

outer rings

2 and 3. Only the point and the point where the cage 5 </ b> A has a crown shape made of the annular body 7. Other configurations and internal specifications are the same as those in the first embodiment. Here, “the same internal dimensions” means that the groove shoulder heights of the inner ring 2 and the outer ring 3 of the bearing are each 0.2 times the diameter of the ball 4, and the function f is “1 <f <1.1. It means that the bearing is designed so as to satisfy.

As shown in FIG. 9, the sealing device 6 is fitted and fixed in a seal groove 3b formed on the inner peripheral surface of the outer ring 3. In the deep groove ball bearing, either one or both of the sealing devices 6 can be omitted. Although a contact seal is shown as the sealing device 6 in FIG. 9, a non-contact seal may be used. A shield made of a metal plate may be provided as the sealing device 6. Grease is sealed in the bearing space. The raceway groove may be referred to as a rolling surface or a raceway surface.

The cage 5A will be described. As shown in FIGS. 9A and 9B, the retainer 5A has a pocket Pt that is partially opened on one side surface 7a of the annular body 7 and holds the ball 4 inside, and is formed in a circle of the annular body 7. It is a crown shape at a plurality of locations in the circumferential direction. The cage 5A is formed, for example, by injection molding or machining a synthetic resin material. As the synthetic resin material, for example, polyamide resin such as nylon, polyether ether ketone, abbreviation PEEK, polyphenylene salside, abbreviation PPS, or the like is used. The cage 5A is formed into a rolling element guide type in which the inner surface of each pocket Pt is a spherical surface having the same curvature, and the ball 4 is fitted in each pocket Pt, thereby restraining in the axial direction, the radial direction, and the circumferential direction. It is configured.

A pair of

claws

8 and 8 projecting axially from both circumferential ends of the pocket Pt on the open side surface of the pocket Pt of the annular body 7 are provided for each pocket Pt. The pair of

claws

8, 8 oppose each other in the circumferential direction, and constitute a part of the pocket Pt between each other. In other words, the inner surfaces of the pair of

claws

8 and 8 are formed along a spherical surface having the same curvature center position and the same curvature radius as the spherical surface forming the pocket bottom surface.

As shown in FIG. 11, a grease containing recess GP is provided between the pockets Pt and Pt adjacent to each other in the circumferential direction of the annular body 7 as a grease pocket for collecting grease. As shown in FIG. 10 (B), the non-pocket side of the grease containing recess GP in the annular body 7 is opened. As shown in FIG. 12, the inner wall portion of the annular body 7 with respect to the cross-sectional shape of the annular body 7 as viewed by cutting the portion where the grease accommodating recess GP is provided along the plane including the axis L <b> 1 of the annular body 7 9 and the connecting portion 10 connecting the circumferentially adjacent pockets Pt and Pt form a grease containing recess GP. As shown in FIG. 11, the grease containing recess GP is surrounded by the inner wall 9 of the annular body 7, the spherical outer wall Pa of the adjacent pockets Pt and Pt, and the connecting portion 10, so that grease can be received. Provided.

The annular body 7 is provided with a communication port Rh that communicates with the grease containing recess GP and the pocket Pt. The communication port Rh has a function of supplying the base oil of the grease stored in the grease receiving recess GP to the balls 4 (FIG. 9) in the pocket Pt. Further, during the bearing operation, the grease adhering to the ball 4 is moved to the grease containing recess GP through the communication port Rh by the relative movement of the ball 4 and the cage 5.

As shown in FIGS. 10A and 10B, the communication port Rh is a notch that communicates with the grease receiving recess GP and the pocket Pt and opens to the inner diameter side of the annular body 7. Here, as shown in FIG. 13, when the plane S1 perpendicular to the axis L1 of the annular body 7 and passing through the center C1 of the pocket Pt is used as a reference, the central portion CP of the communication port Rh with respect to the plane S1. The angle α1 is preferably in the range of 20 degrees to 50 degrees. Here, the central portion CP of the communication port Rh refers to the central portion CP of the pocket Pt in the circumferential direction at the communication port Rh, and in other words, the angle α1 is the center portion CP and the center C1 of the pocket Pt. The angle formed by the straight line L2 connecting the plane S1 and the plane S1. When the cage 5A is manufactured by injection molding, it is difficult to remove the cage from the mold when the angle α1 of the central portion CP of the communication port Rh with respect to the plane S1 is less than 20 degrees. Further, the contact portions between the balls 4 and the inner and

outer rings

2 and 3, that is, the raceway surfaces 2a and 3a, have a small amount of grease. Therefore, if the angle α1 is small, the effect of scraping the grease into the grease containing recess GP is small. By making the angle α1 in the range of 20 degrees or more and 50 degrees or less, it becomes easy to manufacture and the effect of scraping the grease into the grease containing recess GP can be enhanced and the torque can be reduced.

As shown in FIG. 14, the size of the communication port Rh, that is, the maximum width dimension H along the circumferential direction of the pocket Pt is preferably 10% or more and 40% or less of the inner diameter d1 of the pocket Pt. If the maximum width dimension H of the communication port Rh is smaller than 10% of the inner diameter d1 of the pocket Pt, it becomes difficult to move the grease through the communication port Rh. When the maximum width dimension H of the communication port Rh is larger than 40% of the inner diameter d1 of the pocket Pt, it is difficult for the pocket Pt to hold the ball 4.

A comparative test will be described. A bearing incorporating the cage according to the second embodiment of the present invention was compared with a bearing incorporating a conventional crown cage. FIGS. 15A and 15B are bearings incorporating the cage according to the second embodiment, and FIGS. 16A and 16B are bearings incorporating a conventional crown cage 50, respectively. The photograph after driving | running on driving | running conditions is shown.
FIG. 25 is a perspective view of a conventional crown-shaped cage 50, and FIG. 26 is a cross-sectional view of the main part of the crown-shaped cage 50. The operating conditions are a deep groove ball bearing bearing model number “6206”, a rotational speed of 1800 min ⁻¹ , and an operating time of about 30 sec.

According to the comparative test, in the cage 5A of the second embodiment, the grease enters the grease accommodating recess GP through the communication port Rh regardless of the grease filling position with respect to the bearing, and compared with the conventional cage 50, the pocket Pt. Less grease on the side. The grease moves to the grease containing recess GP in a very short time and becomes low torque. If grease is initially sealed in the grease containing recess GP, the torque at the time of starting can be reduced.

According to the second embodiment described above, the same effects as those of the first embodiment can be obtained. In addition, the cage 5A of FIG. 11 is provided with the grease accommodating recess GP, and the grease accommodating recess GP and the ball 4 (FIG. 9). Since the communication port Rh that communicates with the pocket Pt that holds the grease is provided, the grease adhering to the ball 4 is moved to the grease containing recess GP through the communication port Rh during the bearing operation. That is, when the ball 4 rotates in the pocket Pt, a part of the grease adhering to the ball 4 reaches the communication port Rh, and further, the ball 4 rotates (that is, relative movement) in the pocket Pt. The part is scraped off by the communication port Rh and is moved by being pressed toward the grease containing recess GP through the communication port Rh by the pressure of the balls 4. Since the grease is stored in the grease containing recess GP and rotates together with the cage 5A, the above-described stirring resistance and shear resistance can be reduced.

In grease lubrication, the base oil of grease acts on lubrication. Since the base oil separated from the grease held in the grease containing recess GP is supplied to the ball 4 through the communication port Rh, the base oil necessary for lubrication can be used. As described above, the present invention is not limited to the use of the bearing, and it is possible to reduce the torque during the operation of the bearing without sacrificing the rolling fatigue life and the grease life, and from the grease held in the grease containing recess GP. The separated base oil can be used for lubrication.

Since the communication port Rh is not a hole but a notch, the effect of scraping off the grease at the edge (edge part) of this notch can be enhanced, and the effect of scraping into the grease containing recess GP can be enhanced. In this case, the mold structure when the cage 5A is manufactured by injection molding can be simplified. Therefore, the manufacturing cost of the cage 5A can be reduced. When the cage 5A is manufactured by injection molding that is excellent in mass productivity, it is easy to process and assemble and reduce costs by using a polyamide-based resin such as nylon as the synthetic resin material. By using polyether ether ketone, abbreviated as PEEK, as the synthetic resin material of the cage 5A, it can be made excellent in high strength, heat resistance, wear resistance, and hydrolysis resistance. By using polyphenylene salside, abbreviated as PPS, as the synthetic resin material for the cage 5A, it is possible to obtain a cage 5A that is excellent in high temperature property, chemical resistance, flame retardancy, and dimensional stability.

From the viewpoint of low environmental load that is strongly demanded for industrial products in recent years, a plant-derived resin material may be used as the cage material. This means the use of bioplastics with zero CO ₂ balance (carbon neutral). This category includes, for example, polylactic acid, polybutylene succinate synthesized from sugars such as sugar cane and corn, or castor oil. Such as polyamide. In order to apply these synthetic resin materials and plant-derived resin materials to the cage 5A, it is generally necessary to increase the strength with glass fibers or carbon fibers.

A third embodiment of the present invention will be described. In the following description, the same reference numerals are given to portions corresponding to the matters described in the preceding forms in each embodiment, and overlapping descriptions are omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in the preceding section. Not only the combination of the parts specifically described in each embodiment, but also the embodiments can be partially combined as long as the combination does not hinder.

The deep groove ball bearing 1B of FIG. 17 incorporates the same grease containing recess GP and the cage 5B provided with the communication port Rh as in the second embodiment, and the following grease is sealed in the bearing space between the inner and

outer rings

2 and 3 Has been. The grease is a grease composition in which an additive is blended with a base grease comprising a base oil and a thickener, and the additive is at least selected from a plant-derived polyphenol compound and its decomposition compound One compound is contained, and the compounding ratio of this compound is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease.

The present applicant encloses a grease composition containing at least one compound selected from (1) plant-derived polyphenol compounds and (2) plant-derived polyphenol compound decomposition compounds for deep groove ball bearings, A quick acceleration / deceleration test and a high temperature durability test were conducted, and it was found that the bearing life could be extended. This is because the compound is easily attached to the metal surface of the bearing rolling surface by the action of the polar group (A), and the substance reacts on the frictional wear surface or the newly formed metal surface exposed by wear, causing the oxide film to roll on the bearing. By forming on the running surface, generation of hydrogen due to decomposition of the grease composition can be suppressed, and unique peeling due to hydrogen embrittlement on the bearing rolling surface can be prevented. (B) The above compound prevents oxidation of the grease composition. This is considered to be because it acts as an agent and can suppress oxidative deterioration. The present invention is based on these findings.

The polyphenol compound that can be used in the third embodiment is an aromatic hydroxy compound having a plurality of hydroxyl groups in one molecule, in which a hydrogen atom of an aromatic hydrocarbon ring is substituted with a hydroxyl group (hydroxy group), and is derived from a plant. It is. Moreover, the degradation compound of the plant-derived polyphenol compound is an aromatic or alicyclic hydroxy compound produced by hydrolysis of the polyphenol compound. In order to obtain the same effect as that of the polyphenol compound, the decomposition compound also preferably has a plurality of hydroxyl groups in one molecule.

Examples of plant-derived polyphenol compounds or degradation compounds that can be used in the present embodiment include tannin, gallic acid, ellagic acid, chlorogenic acid, caffeic acid, quinic acid, curcumin, quercetin, pyrogallol, theaflavin, anthocyanin, rutin, lignan. And catechins. In addition, polyphenol compounds obtained from plant-derived sesamin, isoflavones, coumarins and the like can also be used. The above polyphenol compounds or their decomposition compounds may be used alone or in combination of two or more.

Among these, tannin, gallic acid or derivatives thereof, ellagic acid or derivatives thereof, chlorogenic acid or derivatives thereof, caffeic acid or derivatives thereof, quinic acid or derivatives thereof, curcumin or It is preferable to use a derivative thereof, quercetin or a derivative thereof. The tannin used in this embodiment is a polyphenol compound that contains many phenolic hydroxyl groups in the molecule and has a relatively large molecular weight as an acidic organic substance. The tannin is an astringent plant component present in oak peel, fushi (garlic), cocoon and the like, and is roughly classified into hydrolyzable tannin and condensed tannin depending on the chemical structure.

Hydrolyzable tannin is hydrolyzed to polyhydric phenolic acid and polyhydric alcohol by acid, alkali and enzyme. As the polyhydric phenol obtained, there are mainly two types of gallic acid and its dimer (in the free state, dehydration cyclization becomes tetracyclic ellagic acid). Examples of the polyhydric alcohol obtained include pyrogallol. Condensed tannin is a product in which multiple molecules of catechin are condensed at a carbon-carbon bond. In the present invention, it is preferable to use a hydrolyzable tannin from which a decomposition product such as gallic acid, ellagic acid, pyrogallol and the like can be obtained.

Gallic acid and ellagic acid used in this embodiment are polyhydric phenol acids (polyphenol compounds) obtained by hydrolyzing hydrolyzable tannin as described above. Gallic acid has a structure shown in the following formula (1), and ellagic acid has a structure shown in the following formula (2).

Derivatives of gallic acid used in the present embodiment include gallic acid esters such as methyl gallate, ethyl gallate, propyl gallate, butyl gallate, pentyl gallate, hexyl gallate, heptyl gallate, and octyl gallate. Examples thereof include gallates such as bismuth acid. Of these, ethyl gallate is more preferred because of its excellent solubility in lubricating oil. Moreover, the same derivative can be used also about ellagic acid.

Chlorogenic acid used in this embodiment is a polyphenol compound contained in coffee beans and the like, and has a structure represented by the following formula (3).

The caffeic acid used in the present embodiment is a hydrolyzate of chlorogenic acid, and is an aromatic hydroxy compound having three hydroxyl groups in the molecule in which the hydrogen atom of the aromatic hydrocarbon ring is substituted with a hydroxyl group. It has the structure shown in 4).

The quinic acid used in the present embodiment is a hydrolyzate of chlorogenic acid, and is an alicyclic hydroxy compound having five hydroxyl groups in the molecule in which hydrogen atoms of the alicyclic hydrocarbon rings are substituted with hydroxyl groups. It has a structure shown in Formula (5).

Curcumin used in this embodiment is a polyphenol compound contained in turmeric or the like and has a structure represented by the following formula (6).

Quercetin used in the present embodiment is a polyphenol compound contained in citrus fruits and has a structure represented by the following formula (7).

The blending ratio of at least one compound selected from a plant-derived polyphenol compound and its decomposition compound is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease. Further, it is preferably 0.1 to 5 parts by weight. When the compounding ratio of the compound is less than 0.05 parts by weight, peeling on the rolling surface due to hydrogen embrittlement cannot be effectively prevented. In addition, the grease cannot be effectively prevented from being deteriorated by oxidation. Even if the compounding ratio of the above compound exceeds 10 parts by weight, the anti-peeling effect and the effect of preventing the oxidative deterioration of the lubricant are hardly further improved.

Examples of base oils that can be used in this embodiment include mineral oils such as spindle oil, refrigerator oil, turbine oil, machine oil, dynamo oil, highly refined mineral oil, liquid paraffin oil, polybutene oil, and GTL oil synthesized by the Fischer-Tropsch method. , Hydrocarbon synthetic oils such as PAO oil, alkylnaphthalene oil, and alicyclic compounds, or natural oils, polyol ester oils, phosphate ester oils, polymer ester oils, aromatic ester oils, carbonate ester oils, diester oils, Non-hydrocarbon synthetic oils such as ester oils such as polyglycol oil, silicone oils, polyphenyl ether oils, alkyl diphenyl ether oils, alkyl benzene oils, and fluorinated oils can be used. These may be used alone or in combination of two or more.

PAO oil is usually an α-olefin or a mixture of isomerized α-olefin oligomers or polymers. Specific examples of α-olefins include 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, -Nonadecene, 1-eicosene, 1-docosene, 1-tetracocene and the like can be mentioned, and usually a mixture thereof is used. As the base oil of the grease composition of the present embodiment, at least one oil selected from alkyl diphenyl ether oil, ester oil and PAO oil is used because of excellent heat resistance and lubricity among the above base oils. preferable. Alkyl diphenyl ether oil and ester oil are more preferably used in combination with PAO oil.

The kinematic viscosity at 40 ° C. of the base oil is preferably 10 to 100 mm ² / sec. More preferably, it is 10 to 70 mm ² / sec. When the kinematic viscosity is less than 10 mm ² / sec, the base oil deteriorates in a short time, and the resulting deterioration promotes the deterioration of the entire base oil. Become. Also, if it exceeds 100 mm ² / sec, the temperature rise of the bearing will increase due to the increase of rotational torque, especially at high speed rotation, and the temperature rise will be large. become unable.

As a thickener of the grease composition of the present embodiment, benton, silica gel, fluorine compound, lithium soap, lithium complex soap, strong lucium soap, calcium complex soap, aluminum soap, aluminum complex soap and other soaps, diurea compounds, Examples include urea compounds such as polyurea compounds. Of these, urea compounds are desirable in view of heat resistance, cost, and the like. A urea compound is obtained by reacting an isocyanate compound and an amine compound. In order not to leave a reactive free radical, the isocyanate group of the isocyanate compound and the amino group of the amine compound are preferably blended so as to be approximately equivalent.

The diurea compound can be obtained, for example, by a reaction between diisocyanate and monoamine. Examples of the diisocyanate include phenylene diisocyanate, tolylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, etc., and monoamines include octylamine, dodecylamine, hexadecylamine, stearylamine, And oleylamine, aniline, p-toluidine, cyclohexylamine and the like. The polyurea compound can be obtained, for example, by reacting diisocyanate with a monoamine or diamine. Examples of the diisocyanate and monoamine include those similar to those used for the production of the diurea compound. Examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, And diaminodiphenylmethane.

A base grease for blending the above-mentioned polyphenol compound and the like can be obtained by blending a thickener such as a urea compound with the base oil. A base grease using a urea compound as a thickener is prepared by reacting an isocyanate compound and an amine compound in a base oil. The blending ratio of the thickener in 100 parts by weight of the base grease is 1 to 40 parts by weight, preferably 3 to 25 parts by weight. If the content of the thickener is less than 1 part by weight, the thickening effect will be reduced, making it difficult to make grease, and if it exceeds 40 parts by weight, the resulting base grease will be too hard and the desired effect will be difficult to obtain. Become.

In addition to the plant-derived polyphenol compound, a known grease additive may be included as necessary. Examples of the additives include antioxidants such as organic zinc compounds and amine compounds, metal deactivators such as benzotriazole, viscosity index improvers such as polymethacrylate and polystyrene, and solid lubricants such as molybdenum disulfide and graphite. Rust preventives such as metal sulfonates and polyalcohol esters, friction reducing agents such as organic molybdenum, oily agents such as esters and alcohols, and antiwear agents such as phosphorus compounds. These can be added alone or in combination of two or more.

The grease composition of this embodiment can improve the life of the grease-sealed bearing by suppressing the occurrence of peculiar delamination due to hydrogen embrittlement and improving the oxidation resistance of the grease under high temperature and high speed.

In each of the following Examples and Comparative Examples, the PAO oil used as the base oil is trade name Sinfluid 601 manufactured by Nippon Steel Chemical Co., Ltd. having a kinematic viscosity of 30 mm ² / sec at 40 ° C., and the alkyl diphenyl ether oil is at 40 ° C. The product name Moresco High Lube LB100 made by Matsumura Sekiyu Co., Ltd. with a kinematic viscosity of 97 mm ² / sec, and the ester oil made by Nippon Steel Chemical Co., Ltd. having a kinematic viscosity of 72 mm ² / sec at 40 ° C. Were used respectively. Moreover, the reagent made from Tokyo Chemical Industry was used for each polyphenol compound.

Examples 1 to 10
In half of the base oil shown in Table 1, 4,4-diphenylmethane diisocyanate (trade name Millionate MT, hereinafter referred to as MDI) manufactured by Nippon Polyurethane Industry Co., Ltd. was dissolved in the proportion shown in Table 1, and the remaining half Monoamine that is twice the equivalent of MDI was dissolved in this base oil. The respective blending ratios and types are shown in Table 1. A solution in which monoamine was dissolved was added while stirring the solution in which MDI was dissolved, and then the reaction was continued at 100 ° C. to 120 ° C. for 30 minutes to produce a diurea compound in the base oil. To this, a plant-derived polyphenol compound and the like and an antioxidant were added in the proportions shown in Table 1, and the mixture was further stirred at 100 to 120 ° C. for 10 minutes. Thereafter, the mixture was cooled and homogenized with three rolls to obtain a grease composition. The obtained grease composition was subjected to a rapid acceleration / deceleration test. Test methods and test conditions are shown below. The results are shown in Table 1.

<Rapid acceleration / deceleration test>
An alternator, which is an example of an electrical accessory, was simulated, and the grease composition was enclosed in an inner ring rotating deep groove ball bearing that supports a rotating shaft, and a rapid acceleration / deceleration test was performed. The rapid acceleration / deceleration test conditions are as follows: the load applied to the pulley attached to the tip of the rotating shaft is set to 1960 N, the operating speed is set to 0 rpm to 18000 rpm, and a current of 0.1 A flows through the test bearing. The test was conducted. Then, abnormal peeling occurred in the bearing, and the time when the vibration of the vibration detector exceeded the set value and the generator stopped (peeling life time, h) was measured. The test was terminated after 500 hours.

Comparative Examples 1 to 3
A base grease was prepared by selecting a thickener and a base oil in the blending ratio shown in Table 1 by the method according to Example 1, and further blended with additives to obtain a grease composition. The obtained grease composition was evaluated by performing the same test as in Example 1. The results are shown in Table 1.

As shown in Table 1, all the rapid acceleration / deceleration tests of Examples 1 to 10 showed 400 hours or more. This is considered to be due to the fact that the specific peeling accompanied with the white structure change generated on the bearing rolling surface could be prevented by the action of the plant-derived polyphenol compound blended as an additive of the grease composition. In contrast, Comparative Examples 1 to 3 containing only an antioxidant (hindered phenol) as an additive resulted in a significantly shorter peel life compared to Examples 1 to 10. It was.

Examples 11 to 17
In half of the base oil shown in Table 2, MDI was dissolved in the proportion shown in Table 2, and in the remaining half of the base oil, monoamine that was twice the equivalent of MDI was dissolved. The blending ratio and type of each are shown in Table 2. A solution in which monoamine was dissolved was added while stirring the solution in which MDI was dissolved, and then the reaction was continued at 100 ° C. to 120 ° C. for 30 minutes to produce a diurea compound in the base oil. To this, a plant-derived polyphenol compound and the like were added at a blending ratio shown in Table 2, and the mixture was further stirred at 100 to 120 ° C. for 10 minutes. Thereafter, the mixture was cooled and homogenized with three rolls to obtain a grease composition. The obtained grease composition was subjected to a high temperature durability test. Test methods and test conditions are shown below. The results are also shown in Table 2.

<High temperature durability test>
Deep groove ball bearing (bearing dimensions: inner diameter 20 mm, outer diameter 47 mm, width 14 mm) is filled with 0.7 g of lubricating composition, bearing outer ring outer diameter temperature 150 ° C, radial load 67 N, axial load 67 N Was rotated at a rotation speed of 10,000 rpm, and the time until seizure was measured. The results are also shown in Table 2.

Comparative Example 4 and Comparative Example 5
In accordance with the method according to Example 11, the base grease was prepared by selecting the thickener and the base oil at the blending ratio shown in Table 2, and the additive was further blended to obtain a grease composition. The obtained grease composition was evaluated by conducting the same test as in Example 11. The results are also shown in Table 2.

As shown in Table 2, Examples 11 to 17 showed excellent high temperature durability with a lifetime of 1400 hours or more in the high temperature durability test. This is considered to be because the plant-derived polyphenol compound blended as an additive of the grease composition was able to suppress oxidative deterioration of the grease composition. On the other hand, in Comparative Examples 4 and 5, the same base oil as in Examples 11 to 17 was used and two kinds of antioxidants were used in combination, but the life was significantly shorter than in Examples 11 to 17. It became.

Here, the life (high temperature durability) of the curcumin-added grease added with curcumin as a plant-derived polyphenol compound was tested with a deep groove ball bearing having a bearing model number “6204” having an inner diameter of 20 mm, an outer diameter of 47 mm, and a width of 14 mm. As shown in FIG. The inner ring rotational speed is 10000 min ⁻¹ , and the outer ring outer diameter portion temperature is 150 ° C. In the figure, the horizontal axis shows the ratio of the amount of grease charged to the total space volume inside the bearing, and the vertical axis shows the grease life, that is, the time until seizure.

According to the test results, the life is slightly longer in the case of 25% grease with the addition of curcumin indicated by the square mark than when the grease life is 38% without the addition of curcumin indicated by the circle in the figure. It can be seen that if 22% grease is added with the addition of curcumin, the life is almost the same as when 38% grease is added without the addition of curcumin. Generally, the smaller the amount of grease charged, the lower the resistance due to the agitation and shearing of the grease by the cage, so that lower torque can be expected. That is, when curcumin is added, the torque can be reduced while maintaining the grease life.

According to the deep groove ball bearing 1B of FIG. 17 described above, the grease is stored in the grease containing recess GP (FIG. 10A) and rotates together with the cage 5B, so that stirring resistance and shear resistance can be reduced. Since the base oil separated from the grease held in the grease containing recess GP is supplied to the ball 4 through the communication port Rh (FIG. 10A), the base oil necessary for lubrication can be used. . By enclosing the grease composition in a bearing incorporating such a cage 5B, it is possible to suppress the occurrence of specific peeling due to hydrogen embrittlement. Further, the oxidation deterioration resistance can be improved as compared with a grease composition containing a conventional antioxidant or the like, and the life of the bearing can be extended under high temperature and high speed.

The torque measurement result will be described. The deep groove ball bearing having the internal specifications shown in FIG. 8 was designated “A”, and the deep groove ball bearing having the crown-shaped cage provided with the grease containing recess GP and the communication port Rh was designated “B”. A deep groove ball bearing in which 25% of grease obtained by adding 2 parts by weight of curcumin to 100 parts by weight of base grease in standard Multemp SRL grease was designated as “C”. The deep groove ball bearing subjected to the torque test is a bearing model number “6206” having an inner diameter of 30 mm, an outer diameter of 62 mm, and a width of 16 mm. The test is performed by fixing the test bearing to a hydrostatic gas bearing capable of supporting both radial load and axial load, and applying radial load to the shaft fitted to the inner ring of the test bearing or applying axial load to the hydrostatic gas bearing. The outer ring rotational torque was measured when a load was applied to the bearing and the shaft was rotated by an external motor. Torque measurement was performed under the following conditions.
Torque measurement conditions Rotational speed: 3000 to 5000 min ⁻¹ , radial load: 0 to 250N, axial load: 0 to 150N

Table 3 shows the results of measuring the outer ring rotational torque under the above torque measurement conditions.

Suppose that the standard bearing is a bearing model number “6206”, a standard nylon crown cage, and 38% of Maltemp SRL grease. In Table 3, the deep groove ball bearing with the internal specifications shown in FIG. 8 incorporates a crown-shaped cage with a grease containing recess GP and a communication port Rh, and curcumin is added to the standard Multemp SRL grease with 100 weight base grease. A grease containing 2% by weight of grease added with 25% by weight is expressed as “A * B * C”. In Table 3, the torques of the A, B, C, and A * B * C bearings are shown as relative values when the torque value of the standard bearing is 100. Among these bearings, “C” and “A * B * C” bearings were filled with 25% of grease obtained by adding 2 parts by weight of curcumin to 100 parts by weight of base grease in standard Multemp SRL grease. The “A” and “B” bearings are the same as the standard bearings in terms of grease, with respect to the additive and the amount of sealing.

As shown in Table 3, the torque reduction effect is recognized with each of the bearings A, B, and C with respect to the standard bearing, but the bearing of A * B * C has a greater synergistic effect than the simple combination effect (A + B + C). The torque value is about half that of the standard bearing. The bearings A, B, and C are technically different torque reduction methods, but it can also be determined from the above results that they do not work in the direction of suppressing the torque reduction effect due to mutual interference. The deep groove ball bearing having the internal specifications shown in FIG. 8 and incorporating a crown-shaped cage having a grease containing recess GP and a communication port Rh is referred to as “A * B”. A standard deep groove ball bearing is equipped with a grease retaining recess GP and a crown-shaped cage with a communication port Rh, and a standard maltemp SRL grease with 2 parts by weight of curcumin added to 100 parts by weight of base grease. 25% encapsulated material is designated as “B * C”. In addition, a deep groove ball bearing with the internal specifications shown in FIG. 8 and 25% encapsulated grease with 2 parts by weight of curcumin added to 100 parts by weight of the base grease is added to the standard Multemp SRL grease. " Even with these “A * B”, “B * C”, and “C * A” bearings, a synergistic effect more than a simple additive effect can be expected. With respect to the bearing “C”, not only curcumin but also a derivative of curcumin and quercetin or a derivative thereof may be used as an additive. Even in these cases, the above-mentioned effects are recognized.

The cage according to the fourth to seventh embodiments will be described.
As shown in FIGS. 19A and 19B, the portion of the annular body 7 of the

cages

5C and 5D where the grease accommodating recess GP is provided is cut by a plane including the axis L1 of the annular body 7. With regard to the cross-sectional shape seen, the connecting portion 10 of the annular body 7 may have

inclined surfaces

10a and 10b that are inclined with respect to the plane S1 perpendicular to the axis L1. A cage 5C according to the fourth embodiment shown in FIG. 19A has an inclined surface 10a that becomes thinner as the thickness of the connecting portion 10 moves toward the inner diameter side indicated by the arrow A1. In this case, the cage rigidity is higher than that of the cage of FIG. 12, and the strength of the cage 5C can be ensured when rotating at high speed. Further, during the bearing operation, the grease accumulated in the grease accommodating recess GP can be smoothly discharged into the bearing space from the inclined surface 10a through the inner wall portion 9 by the centrifugal force caused by the rotation. A cage 5D according to the fifth embodiment shown in FIG. 19B has an inclined surface 10b that becomes thicker as the thickness of the connecting portion 10 moves toward the inner diameter side indicated by the arrow A1. In this case, the grease stored in the grease receiving recess GP can be held so as not to leak during the bearing operation.

A cage 5E according to the sixth embodiment shown in FIG. 19C has an inclined surface 9a that becomes thinner as the thickness of the inner wall portion 9 moves toward the opposite pocket side indicated by the arrow A2. In this case, during the bearing operation, the grease stored in the grease accommodating recess GP can be smoothly discharged from the inclined surface 9a into the bearing space by the centrifugal force due to the rotation. A cage 5F according to the seventh embodiment shown in FIG. 19D has an inclined surface 9b that becomes thicker as the wall thickness of the inner wall portion 9 goes toward the non-pocket side. In this case, it is possible to hold the grease stored in the grease receiving recess GP so as not to leak during the bearing operation.

The cage 5G according to the eighth embodiment in FIG. 20 is provided with a cover portion 11 that covers the other side surface 7b on the opposite side of the grease receiving recess GP in the annular body 7. For example, the shape having the cover portion 11 can be easily manufactured by machining using a machining center or the like. According to the cage 5G, in the case of high-speed rotation, it is possible to prevent the grease held in the grease containing recess GP by the cover portion 11 from leaking.

21. The cage 5H according to the ninth embodiment in FIG. 21 is manufactured by injection molding, and the communication port Rh is provided so as to widen from the pocket Pt side toward the grease containing recess GP side. In particular, the non-pocket side portion Rha of the communication port Rh is formed parallel to the axis L1 of the annular body 7. In this case, it is possible to easily remove the cage 5H from the injection mold. In addition, a mold for forming the communication port Rh can be applied not to the pocket Pt side where high-precision machining is required for the mold but to the mold on the grease housing recess GP side that is relatively easy to process. Therefore, the manufacturing cost of the mold can be reduced.

The cage 5I according to the tenth embodiment in FIG. 22 has a recess 13 in the pocket opening edge 12 on the outer diameter side of the annular body on the inner surface of the pocket Pt. In this example, two recesses 13 are provided on the pocket opening edge 12. Each of these recesses 13 extends from the pocket opening edge 12 to the vicinity of the ball arrangement pitch circle toward the inner diameter side of the annular body. The two recessed portions 13 are located on both sides of the center L3 in the cage circumferential direction at the pocket opening edge 12 of the pocket Pt. The shape of the inner surface of each recess 13 is an arc having a radius of curvature smaller than the radius of curvature of the concave spherical surface that forms the inner surface of the pocket Pt. The cross-sectional shape is synonymous with a cross-sectional shape obtained by cutting the recess 13 along a plane perpendicular to the axis L1 of the annular body 7. Each dent 13 has a shape that gradually decreases from the annular body outer diameter side toward the ball arrangement pitch circle in the radial direction of the cage, that is, gradually becomes shallower and narrower.

In the bearing incorporating the crown-shaped cage 5I provided with the recess 13, scraping of grease at the pocket opening edge 12 on the outer diameter side of the annular body is reduced by the recess 13. The grease that has entered the pocket Pt from the recess 13 moves to the inner ring 2 (FIG. 8) side and is leveled around the ball arrangement pitch circle. For this reason, it becomes possible to draw more grease in the bearing into the grease containing recess GP. In addition, you may provide the recessed part 13 only in one place, or three or more places.

23. The cage 5J according to the eleventh embodiment in FIG. 23 is provided with a groove 14 at the bottom of the inner surface of the pocket Pt. This groove part 14 consists of a single groove | channel formed along the ball | bowl arrangement pitch circle | round | yen of the bottom face in a pocket inner surface. Grease containing a thickener and base oil is stored in the grease containing recess GP, and base oil necessary for lubrication separated from the grease is moved to the pocket Pt through the communication port Rh, thereby contributing to lubrication. Since a part of the base oil separated from the grease enters the groove portion 14 shown in FIG. 22, the viscous shear resistance due to the base oil between the balls 4 (FIG. 8) and the pocket Pt can be reduced. Therefore, it can contribute to lower torque.

As in the cage 5K according to the twelfth embodiment shown in FIG. 24, the partition plate 15 may be provided in the grease containing recess GP. The partition plate 15 in this example divides the grease containing recess GP in two, and is arranged in parallel to the axis L1. Such a partition plate 15 restricts the movement of the grease in the grease accommodating recess GP, and the grease easily adheres to the inner wall portion 9 of the grease accommodating recess GP. Therefore, the grease can be easily held in the grease containing recess GP. The partition plate 15 can be applied in a form that does not completely partition the grease containing recess GP or in a form that is not parallel to the axis L1.

The grease may be initially sealed in the grease containing recess GP, and the grease on the pocket Pt side may be reduced in advance. In this case, the effect that a part of the grease is scraped off at the communication port Rh is lower than that of the above embodiments, but the torque at the time of starting can be reduced by the amount of grease on the pocket Pt side being small. Further, since the base oil separated from the grease enclosed in the grease containing recess GP is supplied to the ball 4 (FIG. 8) through the communication port Rh, the base oil necessary for lubrication can be used.

In the second to twelfth embodiments, an angular ball bearing may be applied instead of the deep groove ball bearing. In the case of an angular ball bearing with a small load load, it is possible to further reduce the torque by reducing the number of balls of the entire bearing, reducing the rotational torque, and using any one of the cages of the present embodiment. In each embodiment, the grease containing recesses are provided between all the pockets of the annular body, but this is not a limitation. It is sufficient to provide at least one grease receiving recess between any pockets.

As application modes that do not require “internal specifications” as a requirement in each of the embodiments described above, there are the following.

[Aspect 1]
The rolling bearing according to aspect 1 is a rolling bearing in which a plurality of balls interposed between inner and outer rings are held in a cage and are grease-lubricated, and the cage is partially opened on one side surface of an annular body. And a pocket for holding a ball inside the annular body at a plurality of locations in the circumferential direction of the annular body, provided with a grease containing recess for collecting grease between pockets adjacent in the circumferential direction of the annular body, There is provided a communication port that communicates with the grease containing recess and the pocket, and moves the grease adhering to the ball to the grease containing recess by the relative movement of the ball and the cage. A grease composition comprising an additive and a base grease comprising an additive, wherein the additive is at least one selected from plant-derived polyphenol compounds and degradation compounds thereof The compound is contained in an amount of 0.05 to 10 parts by weight based on 100 parts by weight of the base grease, and the plant-derived polyphenol compound contains curcumin or a derivative thereof, and quercetin or a derivative thereof. Either one or both.

According to this configuration, when the ball rotates in the pocket, a part of the grease attached to the ball reaches the communication port, and further, the ball rotates in the pocket, so that a part of the grease is, for example, the communication port. The grease is pressed and moved through the communication port by scraping with the edge of the ball or the pressure of the balls. Since the grease is stored in the grease containing recess and rotates together with the cage, the above-described stirring resistance and shear resistance can be reduced. In lubrication with grease, the base oil of grease acts on lubrication. Since the base oil separated from the grease held in the grease containing recess is supplied to the ball through the communication port, the base oil necessary for lubrication can be used.

The occurrence of peculiar peeling due to hydrogen embrittlement can be suppressed by enclosing the grease composition in a bearing incorporating such a cage. Further, the oxidation deterioration resistance can be improved as compared with a grease composition containing a conventional antioxidant or the like, and the life of the bearing can be extended under high temperature and high speed.

[Aspect 2]
In the first aspect, the communication port may be a notch that allows the grease-receiving recess and the pocket to communicate with each other and opens to the inner diameter side of the annular body.

[Aspect 3]
In the aspect 1, the angle of the central portion of the communication port with respect to the plane that is a plane perpendicular to the axis of the annular body and passes through the center of the pocket may be in the range of 20 degrees to 50 degrees.

[Aspect 4]
In aspect 1, the maximum width dimension along the circumferential direction of the cage of the pocket at the communication port may be in the range of 10% to 40% of the inner diameter of the pocket.

[Aspect 5]
In aspect 1, with respect to a cross-sectional shape obtained by cutting a portion where the grease containing recess is provided in the annular body along a plane including the axis of the annular body, adjacent to the inner wall portion and the circumferential direction of the annular body A connecting portion connecting the pockets forming the grease containing recess, the inner wall portion having an inclined surface inclined with respect to the axis, and the connecting portion inclined with respect to a plane perpendicular to the axis. It is good also as what includes any one or both of what has an inclined surface.

[Aspect 6]
In the first aspect, a partition plate may be provided in the grease containing recess.

[Aspect 7]
In aspect 1, you may provide the cover part which covers the other side surface of the said annular body opposite the pocket side of a grease accommodation recessed part.

[Aspect 8]
In the first aspect, a recess may be provided on the pocket opening edge on the outer diameter side of the annular body on the inner surface of the pocket.

[Aspect 9]
In the first aspect, a groove may be provided at the bottom of the inner surface of the pocket.

[Aspect 10]
In aspect 1, the cage is manufactured by injection molding, and the communication port may be provided so as to extend in parallel with the axis of the annular body or from the pocket side toward the grease-accommodating concave portion.

[Aspect 11]
In aspect 1, the cage may include a synthetic resin material or a plant-derived resin material.

[Aspect 12]
In the first aspect, grease may be initially sealed in the grease receiving recess.

[Aspect 13]
In aspect 1, the rolling bearing may be a deep groove ball bearing or an angular ball bearing.

[Aspect 14]
In aspect 1, when the rolling bearing is a deep groove ball bearing, a sealing device that closes the bearing space between the inner and outer rings may be provided in the outer ring.

As described above, the preferred embodiments have been described with reference to the drawings. However, those skilled in the art will readily assume various changes and modifications within the obvious scope by looking at the present specification. Accordingly, such changes and modifications are to be construed as within the scope of the invention as defined by the appended claims.

1, 1A, 1B Deep groove ball bearing 2 Inner ring 2a Raceway groove 3 Outer ring 3a Raceway groove 4 Balls 5 to 5K Cage 6 Sealing device 7 Annular body 8 Claw 9 Inner wall part 10 Connection part 11 Cover part 12 Pocket opening edge 13 Recess part 14 Groove GP Grease receiving recess Pt Pocket Rh Communication port

Claims

A deep groove ball bearing in which a ball is interposed between an inner ring and an outer ring,
The inner and outer ring groove shoulder heights are each 0.2 times the ball diameter, and the inner and outer ring raceway grooves, groove shoulder height, ball diameter, number of balls, and ball pitch circle diameter are given by Deep groove ball bearing set to range.
The deep groove ball bearing according to claim 1, wherein the ball is held in a cage and lubricated by grease,
0.8d m <d P <d m
The retainer has a crown shape that is partially open on one side surface of the annular body and has pockets for holding balls therein in a plurality of circumferential directions of the annular body, and the circumferential direction of the annular body A grease containing recess for storing grease is provided between the pockets adjacent to each other. The grease containing recess and the pocket communicate with each other, and the grease adhering to the ball is moved to the grease containing recess by the relative movement of the ball and the cage. Deep groove ball bearings with communication ports
The grease composition according to claim 2, wherein the grease is a grease composition obtained by blending an additive with a base grease comprising a base oil and a thickener.
The additive contains at least one compound selected from a plant-derived polyphenol compound and its decomposition compound, and the compounding ratio of this compound is 0.05 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the base grease. ,
The plant-derived polyphenol compound is a deep groove ball bearing which is one or both of curcumin or a derivative thereof and quercetin or a derivative thereof.
3. The deep groove ball bearing according to claim 2, wherein the communication port is a notch that communicates the grease-receiving recess and the pocket and opens to the inner diameter side of the annular body.
3. The deep groove ball bearing according to claim 2, wherein an angle of a central portion of the communication port with respect to the plane that is perpendicular to the axis of the annular body and passes through the center of the pocket is in a range of 20 degrees to 50 degrees.
3. The deep groove ball bearing according to claim 2, wherein the maximum width dimension along the circumferential direction of the cage of the pocket at the communication port is in the range of 10% to 40% of the inner diameter of the pocket.
The cross-sectional shape of the annular body according to claim 2, wherein the portion where the grease containing recess is provided is cut by a plane including the axis of the annular body.
The connecting portion that connects the inner wall portion of the annular body and the pockets adjacent in the circumferential direction forms the grease containing recess,
A deep groove ball bearing including one or both of the inner wall portion having an inclined surface inclined with respect to the axis and the connecting portion having an inclined surface inclined with respect to a plane perpendicular to the axis.
3. The deep groove ball bearing according to claim 2, wherein a partition plate is provided in the grease containing recess.
3. The deep groove ball bearing according to claim 2, wherein a cover portion for covering the other side surface of the annular body on the side opposite to the pocket of the grease containing recess is provided.
3. The deep groove ball bearing according to claim 2, wherein a concave portion is provided at a pocket opening edge on the outer diameter side of the annular body on the inner surface of the pocket.
3. The deep groove ball bearing according to claim 2, wherein a groove is provided at the bottom of the inner surface of the pocket.
3. The deep groove ball bearing according to claim 2, wherein the cage is manufactured by injection molding, and the communication port is provided so as to extend in parallel with the axial center of the annular body or from the pocket side toward the grease receiving recess side. .
3. The deep groove ball bearing according to claim 2, wherein grease is initially sealed in the grease receiving recess.
3. The deep groove ball bearing according to claim 2, wherein the outer ring is provided with a sealing device for closing a bearing space between the inner and outer rings.
A method of designing a deep groove ball bearing in which a ball is interposed between an inner ring and an outer ring,
Arbitrary values are given to the following formulas a and b under the condition of a <b, and the inner and outer ring raceway grooves, groove shoulder heights, ball diameters, the number of balls, and the pitch circles of the balls so as to satisfy the following formulas Design method of deep groove ball bearings to design the diameter.
The method for designing a deep groove ball bearing according to claim 15, wherein groove shoulder heights of the inner ring and the outer ring are each 0.2 times the diameter of the ball, and a = 1 and b = 1.1.
According to claim 15, 0.8d m <d p < d m
Design method for deep groove ball bearings.
16. The method for designing a deep groove ball bearing according to claim 15, wherein the radial cross section is a cross section obtained by cutting a portion of the inner and outer races in contact with the raceway groove along the axial plane.