JP2011208663A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing capable of reducing torque in bearing operation, without sacrificing the rolling fatigue service life and the grease service life, in the rolling bearing used in grease lubrication.SOLUTION: A groove shoulder height of an inner ring and an outer ring is respectively 0.2 time of a diameter of a ball, and a track groove, the groove shoulder height, a diameter of a ball, the number of balls and a pitch circle diameter of the ball of the inner-outer rings, are set in a range of formula (1), and 0.8d<d<dis satisfied. A grease storage recessed part GP is arranged in a crown-shaped cage 5, and a communicating port Rh is arranged for communicating the grease storage recessed part GP and a pocket Pt.

Description

  The present invention relates to a rolling bearing, and relates to a technique capable of reducing torque during bearing operation without sacrificing rolling fatigue life and grease life.

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 1).
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 2).
As a conventional technique for reducing torque by using other cages, for example, a structure in which a groove having a buffering action is provided between cage pockets when a rolling element collides with a pocket is disclosed (Patent Document 3).
As a prior art for reducing the torque of other bearings, there has been disclosed one in which the composition and shape of the bearing seal portion are changed (Patent Document 4).

Japanese Patent No. 3875108 Japanese Patent Laid-Open No. 10-238543 JP 2009-19766 Gazette Japanese Patent No. 3772688

Lundberg- Palmgren theory: T. Harris and M. Kotzalas, Rolling Bearing Analysis, Fifth Edition, Essential Concepts of Bearing Technology, CRC Press (2007), p. 221.)

Depending on the application of the bearing, the grease, seal, etc. cannot be changed, so the torque reduction method using grease, seal, etc. limits its use.
In the cage that takes in the minimum amount of lubricant between the inner circumferential surface of the cage pocket and the rolling surface of the ball, the effect of torque reduction can be obtained when a large amount of grease is sealed in the bearing space. Absent. 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.
In the cage with the above-mentioned groove having a buffering action between the cage pockets, torque reduction at the time of start-up and misalignment can be expected, but when the rotation is stable, it is not different from the conventional cage Torque.

  The present applicant has shown an invention for reducing the torque by extracting parameters between the bearing ring and the shape and number of balls, which are the internal design specifications of the rolling bearing, and defining the functional relationship between them. (Japanese Patent Application No. 2009-99705). In general, when these parameters are set so that the torque is low, the basic dynamic load rating is reduced and the rolling fatigue life is also reduced. However, in the present invention, both low torque and basic dynamic load rating are achieved. 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.

  In addition, the applicant of the present invention added hydrogen embrittlement by adding at least one compound selected from a plant-derived polyphenol compound and its decomposition compound as an antioxidant to a base grease comprising a base oil and a thickener. It has been shown that it is possible to provide a grease that has an excellent anti-peeling effect due to the use and can be used for a long time under high temperature or high speed conditions (Japanese Patent Application 2009-45709).

  An object of the present invention is a rolling bearing used in grease lubrication, which is not limited to the application of the bearing, and can reduce the torque during the bearing operation without sacrificing the rolling fatigue life and the grease life. Is to provide.

A rolling bearing according to a first aspect of the present invention is a rolling bearing in which a plurality of balls interposed between inner and outer rings are held in a cage and grease lubricated, and the groove shoulder heights of the inner ring and outer ring are each equal to the diameter of the ball. 0.2 times, set the inner and outer ring raceway grooves, groove shoulder height, ball diameter, number of balls, and ball pitch circle diameter within the range of the following formula,
And a _{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. It is characterized in that a communication port is provided.

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 (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 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 ball size are set so that 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 rolling bearing having a low torque while having a sufficient basic dynamic load rating can be realized.
The groove shoulder heights of the inner and outer rings 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 obtained based on the theory of Lundberg-Palmgren (Non-Patent Document 1) that 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 above 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 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.

  A rolling bearing according to a second aspect of the present invention is a rolling bearing in which a plurality of balls interposed between inner and outer rings are held in a cage and grease lubricated, and the cage is partially on one side of an annular body. It has a crown shape that has pockets that are open and hold balls inside at a plurality of circumferential positions of the annular body, and is provided with a grease containing recess for collecting grease between pockets adjacent to the circumferential direction of the annular body. The grease containing recess and the pocket communicate with each other, provided with a communication port for moving the grease adhering to the ball to the grease containing recess by the relative movement of the ball and the cage, the grease comprises a base oil, A grease composition comprising an additive added to a base grease comprising a thickener, wherein the additive is selected from plant-derived polyphenol compounds and their decomposition compounds It contains at least one 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, and the plant-derived polyphenol compound contains curcumin or a derivative thereof, and quercetin or It is characterized by being either one or both of the derivatives.

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.

  By enclosing the grease composition in a bearing incorporating such a cage, 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.

1st invention WHEREIN: The said grease is a grease composition formed by mix | blending an additive with the base grease which consists of a base oil and a thickener, Comprising: The said additive is a plant-derived polyphenol compound and its decomposition | disassembly Containing at least one compound selected from the compounds, the compounding ratio of this compound being 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, 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 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 axis 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 recessed part in the bottom part of the inner surface of the said pocket. In this case, since a part of the base oil separated from the grease enters the recess, the viscous shear resistance due to the base oil between the ball and the pocket 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 expand 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 cage may include a synthetic resin material or a plant-derived resin material. When a cage is manufactured by injection molding with excellent mass productivity, it is easy to process and assemble and reduce costs by using a polyamide-based resin such as nylon as a synthetic resin material. By using polyether ether ketone, abbreviated as PEEK, as the synthetic resin material of the cage, 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 of the cage, it is possible to obtain a cage that is excellent in high temperature property and chemical resistance, and has high flame resistance and dimensional stability.
From the viewpoint of low environmental load that is strongly demanded for industrial products in recent years, plant-derived resin materials are used as cage materials. 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.

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.
The rolling bearing may be a deep groove ball bearing or an angular ball bearing.
A sealing device for closing the bearing space between the inner and outer rings may be provided on the outer ring.

A rolling bearing according to a first aspect of the present invention is a rolling bearing in which a plurality of balls interposed between inner and outer rings are held in a cage and grease lubricated, and the groove shoulder heights of the inner ring and outer ring are each equal to the diameter of the ball. 0.2 times, set the inner and outer ring raceway grooves, groove shoulder height, ball diameter, number of balls, and ball pitch circle diameter within the range of the following formula,
And a _{0.8d m <d P <d m} , the retainer pockets for holding the balls within a part is opened on one side surface of the annular body, having a plurality of circumferential locations of the annular body The crown-shaped body is provided with a grease receiving recess for collecting grease between pockets adjacent to each other in the circumferential direction of the annular body, and the grease attached to the ball is communicated with the grease storing recess and the pocket. Because the communication port that moves to the grease containing recess by relative movement with the cage is provided, the rolling bearing used in grease lubrication is not limited to the application of the bearing, without sacrificing rolling fatigue life and grease life, The torque can be reduced during the operation of the bearing.

  A rolling bearing according to a second aspect of the present invention is a rolling bearing in which a plurality of balls interposed between inner and outer rings are held in a cage and grease lubricated, and the cage is partially on one side of an annular body. It has a crown shape that has pockets that are open and hold balls inside at a plurality of circumferential positions of the annular body, and is provided with a grease containing recess for collecting grease between pockets adjacent to the circumferential direction of the annular body. The grease containing recess and the pocket communicate with each other, provided with a communication port for moving the grease adhering to the ball to the grease containing recess by the relative movement of the ball and the cage, the grease comprises a base oil, A grease composition comprising an additive added to a base grease comprising a thickener, wherein the additive is selected from plant-derived polyphenol compounds and their decomposition compounds It contains at least one 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, and the plant-derived polyphenol compound contains curcumin or a derivative thereof, and quercetin or Because it is one or both of its derivatives, in rolling bearings used in grease lubrication, it is not limited to bearing applications, and it can reduce torque during bearing operation without sacrificing rolling fatigue life and grease life. Can be planned.

It is sectional drawing of the rolling bearing which concerns on one Embodiment of this invention. (A) is the perspective view which looked at the retainer of the rolling 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 rolling bearing, (B) is the side view seen from the pocket side of the cage after operating the rolling bearing. (A) is a side view seen from the side opposite the pocket of the cage after operating a conventional rolling bearing as a comparative example, and (B) is a side view seen from the pocket side of the cage after operating the rolling bearing. It is. It is sectional drawing for demonstrating the detailed structure of the rolling bearing. 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 f. It is sectional drawing of the rolling bearing which concerns on other 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. It is sectional drawing which shows several examples of the cross-sectional shape of the grease accommodating recessed part in the holder | retainer which concerns on further another embodiment of this invention. It is a perspective view of the holder | retainer which concerns on other embodiment of this invention. It is sectional drawing of the principal part of the holder | retainer which concerns on further another embodiment of this invention. It is a perspective view of the holder | retainer which concerns on other embodiment of this invention. It is a perspective view of the holder | retainer which concerns on other 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 which concerns on further another 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.

  An embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the rolling bearing 1 according to this embodiment is a sealed deep groove ball bearing, and includes an inner ring 2, an outer ring 3, a plurality of balls 4, a cage 5, and inner and outer rings 2 and 3. And sealing devices 6 and 6 for closing the bearing space therebetween. A sealing device 6 is fitted and fixed in each seal groove 3 b 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. 1, a non-contact seal may be used. A shield made of a metal plate may be provided as the sealing device 6. The outer ring 3 has a raceway groove 3a on the inner periphery, and the inner ring 2 has a raceway groove 2a facing the raceway groove 3a. A plurality of balls 4 are interposed between the raceway grooves 2 a and 3 a, and a cage 5 holds the plurality of balls 4. Grease is sealed in the bearing space. The raceway groove may be referred to as a rolling surface or a raceway surface. The ball 4 is made of, for example, a steel ball.

The cage 5 will be described.
As shown in FIGS. 2 (A) and 2 (B), the retainer 5 has a pocket Pt that is partially opened on one side surface 7a of the annular body 7 and holds the ball 4 therein, and a circular shape of the annular body 7. It is a crown shape at a plurality of locations in the circumferential direction. The cage 5 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 5 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, 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 and 8 are opposed to 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 the 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. 3, between the pockets Pt and Pt adjacent to the circumferential direction of the annular body 7, a grease containing recess GP is provided as a grease pocket for collecting grease. As shown in FIG. 2 (B), the non-pocket side of the grease containing recess GP in the annular body 7 is opened. As shown in FIG. 4, 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 containing 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. 3, the grease accommodating recess GP is surrounded by the inner wall portion 9 of the annular body 7, the spherical outer wall portion Pa of the adjacent pockets Pt and Pt, and the connecting portion 10, so that grease can be accommodated. Provided.

  As shown in FIG. 3, the annular body 7 is provided with a communication port Rh that communicates with the grease receiving 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. 1) 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. 2A and 2B, 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. 5, 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. It is preferable that the angle α1 of the central portion of the communication port Rh with respect to the plane S1 is in the range of 20 degrees to 50 degrees. When the cage 5 is manufactured by injection molding, it is difficult to remove the cage from the mold if the angle α1 of the central portion of the communication port Rh with respect to the plane S1 is as small as 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. 6, the size of the communication opening Rh, that is, the maximum width dimension H along the circumferential direction of the cage 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 a cage according to an embodiment of the present invention was compared with a bearing incorporating a conventional crown cage. FIGS. 7A and 7B are bearings incorporating the cage according to the embodiment, and FIGS. 8A and 8B are bearings incorporating a conventional crown cage 50, respectively. The photograph after driving with is shown.
FIG. 24 is a perspective view of a conventional crown-shaped cage 50, and FIG. 25 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 5 of the present invention, the grease enters the grease containing recess GP through the communication port Rh regardless of the grease filling position with respect to the bearing, and is closer to the pocket Pt side than the conventional cage 50. Less grease. 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.

A method for designing a deep groove ball bearing according to an embodiment of the present invention will be described.
The main dimensions of the deep groove ball bearing, that is, the inner diameter, the outer diameter, the width, and the chamfer dimension are standardized by the International Organization for Standardization, abbreviated ISO. The main dimensions of the rolling bearing defined in Japanese Industrial Standard JIS B 1512 are also defined in accordance with this ISO.
As shown in FIG. 9, the shape of the track portion of the deep groove ball bearings, the diameter of the ball 4 Da, pitch diameter dp, raceway groove 2a, 3a of the diameter _{d 2a,} (referred to as the groove diameter) _{d 3a,} Mizokatadaka It can be determined by the _length H _2a , 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. In FIG. 9, the seal groove of the inner and outer rings is omitted, and the sealing device 6 is simply shown.

  Here, it is considered that the friction torque between the ball 4 of the deep groove ball bearing and the race is generated by the traction of the lubricating oil and the rolling viscous resistance. Considering a deep groove ball bearing having an inner diameter of 30 mm, an outer diameter of 62 mm, and a width of 16 mm, bearing 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, if the diameter Da of the balls 4 is small, the number of balls Z is small, the pitch circle diameter dp is small, the raceway groove curvature ratio of the inner ring 2 is large, and the raceway groove curvature ratio of the outer ring 3 is large, the torque becomes low. I understand that. The raceway groove curvature ratio of the inner ring 2 is a value obtained by dividing the radius of curvature of the raceway groove 2a formed in the outer circumferential surface of the inner ring 2 by 1/2 of the diameter Da of the ball 4, that is, the raceway groove of the inner ring 2. Curvature ratio = (2 × radius of curvature of raceway groove 2a / diameter Da of 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 Da / 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. The ratio of the groove shoulder heights H _2a and H _{3a to} the ball diameter Da 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. 9, if the areas S _i , S _o forming the clearances between the raceway grooves 2a, 3a of the inner and outer rings 2, 3 and the balls 4 in the radial cross section are set as design parameters, these areas S _i , The greater the S _{o, 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.

Larger than a certain value which the 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 _3a If the diameter Da of the balls 4, the number of balls Z, and the pitch circle diameter dp of the balls 4 are designed, a low torque deep groove ball bearing having a sufficient basic dynamic load rating can be realized.

The ratio of the groove shoulder heights H _2a and H _3a to the diameter Da of the ball 4 is “0.2”, the raceway groove curvature ratio is “1.04” for the inner and outer rings 2 and 3, and the pitch circle diameter dp is the bearing diameter. The average of the inner and outer diameters, that is, the inner ring inner diameter is added to the outer ring outer diameter and divided by 2. When the diameter Da of the balls 4 and the number of balls Z are the values of a general commercially available bearing, the above f is obtained as shown in FIG. The track groove curvature ratio varies depending on the manufacturer and product number, but in order to generalize and discuss, in this embodiment, the value used for calculating the basic dynamic load rating defined in JIS B 1518 of the Japanese Industrial Standards It was. In this case, in a very general design, generally 0.9 <f <1
Holds. The larger f is, the lower the torque becomes, but 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 a rolling bearing is defined in Japanese Industrial Standard JIS B 1518. This is based on the assumption that the raceway groove curvature ratio of the inner and outer rings is “1.04”. It is configured as. 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 Da 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.

Raceway groove curvature ratio of the inner and outer rings 2,3 m _i, to the basic dynamic load rating obtained at design conditions considering the change in m _o, when attempting to reserve a basic load rating of 0.9 times or more, the function f 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.

According to the rolling bearing 1 described above, the raceway grooves 2a of the inner and outer rings 2,3, 3a, groove shoulder height _{H 2a, H 3a,} the diameter of the ball 4 Da, number of balls Z, and the pitch circle diameter dp such balls 4 Is set as described above, it is possible to secure a sufficient basic dynamic load rating and reduce torque.
Further, the retainer 5 is provided with a grease accommodating recess GP, and a communication port Rh is provided for communicating the grease accommodating recess GP with the pocket Pt for holding the ball 4, so that the grease adhering to the ball 4 is communicated during the bearing operation. The grease is moved to the grease containing recess GP by the opening Rh. 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 5, 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 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 grease at the edge (edge part) of the 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 5 is manufactured by injection molding can be simplified. Therefore, the manufacturing cost of the cage 5 can be reduced.
When the cage 5 is manufactured by injection molding with excellent 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 5, 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 of the cage 5, the cage 5 is excellent in high temperature property and chemical resistance, and has high flame resistance 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 5, it is generally necessary to increase the strength with glass fibers or carbon fibers.

Another embodiment of the present invention will be described.
In the following description, the same reference numerals are given to the portions corresponding to the matters described in the preceding forms in each embodiment, and the overlapping description is 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 rolling bearing 1 </ b> A in FIG. 16 incorporates the above-described grease receiving recess GP and the cage 5 provided with the communication port Rh, and the following grease is sealed in the bearing space between the inner and outer rings 2 and 3.
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 rolling bearings. An 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 present invention is an aromatic hydroxy compound having a plurality of hydroxyl groups in one molecule obtained by substituting a hydrogen atom of an aromatic hydrocarbon ring with a hydroxyl group (hydroxy group), and is derived from a plant.
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 invention include tannin, gallic acid, ellagic acid, chlorogenic acid, caffeic acid, quinic acid, curcumin, quercetin, pyrogallol, theaflavin, anthocyanin, rutin, lignan, Catechin etc. are mentioned. 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.
Tannin used in the present invention is a polyphenol compound containing a large number of phenolic hydroxyl groups in the molecule and having a relatively large molecular weight as an acidic organic substance. The tannin is an astringent plant component present in oak skin, fushi (eroded), cocoon and the like, and is roughly classified into hydrolyzable tannin and condensed tannin depending on the chemical structure.

  Hydrolyzable tannin is hydrolyzed into polyhydric phenol 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 obtained by condensing a plurality of molecules of catechin through carbon-carbon bonds. 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 the present invention 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 invention include gallic acid esters such as methyl gallate, ethyl gallate, propyl gallate, butyl gallate, pentyl gallate, hexyl gallate, heptyl gallate, octyl gallate, and gallic acid. Examples thereof include gallates such as bismuth. 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 the present invention 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 invention is a hydrolyzate of chlorogenic acid, and is an aromatic hydroxy compound having three hydroxyl groups in the molecule in which a hydrogen atom of an aromatic hydrocarbon ring is substituted with a hydroxyl group. ).

The quinic acid used in the present invention is a hydrolyzate of chlorogenic acid, and is an alicyclic hydroxy compound having five hydroxyl groups in the molecule in which the hydrogen atom of the alicyclic hydrocarbon ring is substituted with a hydroxyl group, and the following formula It has the structure shown in (5).

Curcumin used in the present invention is a polyphenol compound contained in turmeric and the like, and has a structure represented by the following formula (6).

Quercetin used in the present invention 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 degradation compound is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease. Furthermore, it is preferably 0.1 to 5 parts by weight. When the blending ratio of the above 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 improved.

  Examples of base oils that can be used in the present invention include mineral oils such as spindle oil, refrigerator oil, turbine oil, machine oil, dynamo oil, highly refined mineral oil, liquid paraffin oil, polybutene oil, GTL oil synthesized by the Fischer-Tropsch method, Hydrocarbon synthetic oil such as PAO oil, alkylnaphthalene oil, alicyclic compound, or natural oil, polyol ester oil, phosphate ester oil, polymer ester oil, aromatic ester oil, carbonate ester oil, diester oil, poly Non-hydrocarbon synthetic oils such as ester oils such as glycol oils, 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 oils are usually a mixture of α-olefins or 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 invention, it is preferable to use at least one oil selected from alkyl diphenyl ether oil, ester oil, and PAO oil because it is excellent in heat resistance and lubricity among the above base oils. . Alkyl diphenyl ether oil and ester oil are more preferably used in combination with PAO oil.

The kinematic viscosity of the base oil at 40 ° C. is preferably 10 to 100 mm ² / sec. More preferably, it is 10-70 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.

Thickeners of the grease composition of the present invention include soaps such as benton, silica gel, fluorine compound, lithium soap, lithium complex soap, strong lucium soap, calcium complex soap, aluminum soap, aluminum complex soap, diurea compound, polyurea Examples include urea compounds such as 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.

  A diurea compound is obtained by reaction of a diisocyanate and a monoamine, for example. 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, Examples include 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 by blending a thickener such as a urea compound with the base oil can be obtained. 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 not be obtained. Become.

  In addition to the plant-derived polyphenol compound, a known grease additive may be contained 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 the present invention can improve the life of a grease-sealed bearing by suppressing the occurrence of peculiar delamination due to hydrogen embrittlement and improving the oxidation resistance degradation of 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 Nippon Steel Chemical's trade name Sinfluid 601 with a kinematic viscosity of 30 mm2 / sec at 40 ° C, and the alkyl diphenyl ether oil is a kinematic fluid at 40 ° C. The product name Moresco High Lube LB100 made by Matsumura Oil Co., Ltd. with a viscosity of 97 mm2 / sec, and the ester oil made by Nippon Steel Chemical Co., Ltd. with a kinematic viscosity of 72 mm2 / sec at 40 ° C. Using. 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 manufactured by Nippon Polyurethane Industry Co., Ltd., hereinafter referred to as MDI) is dissolved in the proportion shown in Table 1, and the remaining half In this base oil, a monoamine that was twice the equivalent of MDI was dissolved. 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 for 30 minutes at 100 ° C. to 120 ° C. to produce a diurea compound in the base oil. To this, a plant-derived polyphenol compound and the like and an antioxidant were added at a blending ratio 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 sealed in a rolling bearing for rotating an inner ring that supports a rotating shaft, and a rapid acceleration / deceleration test was performed. The rapid acceleration / deceleration test conditions are as follows: the load load on 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, the rapid acceleration / deceleration tests of Examples 1 to 10 all 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. On the other hand, in Comparative Example 1 in which only the antioxidant (hindered phenol) was blended as an additive, the peeling occurrence life was significantly shorter than those in Examples 1 to 10.

Example 11 to Example 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 for 30 minutes at 100 ° C. to 120 ° C. 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>
Rolling 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 It was rotated at a rotational speed of 10000 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 Example 4, two types of antioxidants were used in combination using the same base oil as in Examples 11 to 17, but the life was significantly shorter than in Examples 11 to 17. It was.

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 adding 25% grease with the addition of curcumin indicated by the square mark than in the case of adding 38% grease 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 rolling bearing 1A of FIG. 16 described above, the grease is stored in the grease accommodating recess GP (FIG. 2) and rotates together with the cage 5, 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. 2), the base oil necessary for lubrication can be used.
By enclosing the grease composition in a bearing incorporating such a cage 5, it is possible to suppress the occurrence of peculiar 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. 9 was designated as “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 as “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 250 N, axial load: 0 to 150 N

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

  The standard bearing is bearing type “6206”, standard nylon crown cage, and 38% of Maltemp SRL grease. In Table 3, a deep groove ball bearing with internal specifications shown in FIG. 9 is incorporated with a crown-shaped cage with a grease receiving recess GP and a communication port Rh, and curcumin is added to a 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 in which the internal specifications of FIG. 9 are set and the crown-shaped cage provided with the grease containing recess GP and the communication port Rh are incorporated 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. 9 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.

Another embodiment of the cage will be described.
As shown in FIGS. 18A and 18B, the portion of the annular body 7 of the cage 5 where the grease accommodating recess GP is provided is cut by a plane including the axis L1 of the annular body 7 and viewed. With respect to the cross-sectional shape, the connecting portion 10 of the annular body 7 may have an inclined surface 10a that is inclined with respect to the plane S1 perpendicular to the axis L1.
The cage 5 shown in FIG. 18 (A) 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. 4, and the strength of the cage 5 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.
The cage 5 shown in FIG. 18B has an inclined surface 10a that becomes thicker as the thickness of the connecting portion 10 goes 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.

The cage 5 shown in FIG. 18C 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.
The cage 5 shown in FIG. 18D has an inclined surface 9a 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 5A of FIG. 19 includes a cover 11 that covers the other side 7b of the annular body 7 on the side opposite to the pocket of the grease containing recess GP. 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 5A, 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.

  The cage 5B shown in FIG. 20 is manufactured by injection molding, and the communication port Rh is provided so as to expand 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 5B 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 5C in FIG. 21 is provided with a recess 13 at 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 L2 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 5C provided with the recess 13, the recess 13 reduces the scraping of grease at the pocket opening edge 12 on the outer diameter side of the annular body. The grease that has entered the pocket Pt from the recess 13 moves to the inner ring 2 (FIG. 1) 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. Note that one or more indentations 13 may be provided.

  The cage 5D of FIG. 22 has a recess 14 at the bottom of the inner surface of the pocket Pt. The recess 14 is formed by a single groove formed along a ball arrangement pitch circle on the bottom surface of the 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 recess 14 shown in FIG. 22, the viscous shear resistance due to the base oil between the ball 4 (FIG. 1) and the pocket Pt can be reduced. Therefore, it can contribute to lower torque.

  Like the cage 5E shown in FIG. 23, 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 through the communication port Rh, the base oil necessary for lubrication can be used.

An angular ball bearing may be applied as the rolling 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.

DESCRIPTION OF SYMBOLS 1,1A ... Rolling bearing 2 ... Inner ring 3 ... Outer ring 4 ... Balls 5-5E ... Cage 6 ... Sealing device 7 ... Ring body 8 ... Claw 9 ... Inner wall part 10 ... Connection part 11 ... Cover part 12 ... Pocket opening edge 13 , 14 ... Recess 15 ... Partition plate GP ... Grease housing recess Pt ... Pocket Rh ... Communication port

Claims (16)

In a rolling bearing in which a plurality of balls interposed between inner and outer rings are held by a cage and grease lubricated,
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 Set to range,
And a _{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 rolling bearing characterized in that a communication port is provided. In rolling bearings in which a plurality of balls interposed between the inner and outer rings are held in a cage and grease lubricated,
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 that allows
The grease is a grease composition formed by adding an additive to a base grease composed of 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 rolling bearing according to claim 1, wherein the plant-derived polyphenol compound is one or both of curcumin or a derivative thereof and quercetin or a derivative thereof. The grease composition according to claim 1, wherein the grease is a grease composition obtained by blending an additive with a base grease composed of 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. ,
A rolling bearing, wherein the plant-derived polyphenol compound is one or both of curcumin or a derivative thereof and quercetin or a derivative thereof.   4. The rolling bearing according to claim 1, wherein the communication port is a notch that allows the grease-receiving recess and the pocket to communicate with each other and opens toward an inner diameter side of the annular body.   5. 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 is 20 degrees or more and 50 degrees according to claim 1. Rolling bearing with the following range.   The maximum width dimension along the cage circumferential direction of the pocket in the communication port according to any one of claims 1 to 5 is in a range of 10% to 40% of the inner diameter of the pocket. Rolling bearing. In any one of Claim 1 thru | or 6, About the cross-sectional shape seen by cut | disconnecting the location in which the grease accommodating recessed part was provided among the said annular bodies by the plane containing the axial center of the said 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 rolling 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.   The rolling bearing according to any one of claims 1 to 7, wherein a partition plate is provided in the grease containing recess.   9. The rolling bearing according to claim 1, wherein a cover portion that covers the other side surface of the annular portion opposite to the pocket of the grease receiving recess is provided in the annular body.   The rolling bearing according to any one of claims 1 to 9, wherein a recess is provided at a pocket opening edge on the outer diameter side of the annular body on the inner surface of the pocket.   The rolling bearing according to claim 1, wherein a recess is provided at the bottom of the inner surface of the pocket.   12. The holder according to claim 1, wherein the retainer is manufactured by injection molding, and the communication port is parallel to the axis of the annular body or from the pocket side toward the grease containing recess. Rolling bearing provided to spread according to.   The rolling bearing according to any one of claims 1 to 12, wherein the cage includes a synthetic resin material or a plant-derived resin material.   The rolling bearing according to any one of claims 1 to 13, wherein grease is initially sealed in the grease containing recess.   The rolling bearing according to any one of claims 1 to 14, wherein the rolling bearing is a deep groove ball bearing or an angular ball bearing.   The rolling bearing according to claim 15, wherein when the rolling bearing is a deep groove ball bearing, a sealing device for closing a bearing space between the inner and outer rings is provided on the outer ring.