JPH11201169A - Rolling bearing - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To suppress the generation of cage noise at the time of start-up at low temperatures, and to improve the bearing acoustic characteristics at low and high temperatures.
Provided is a rolling bearing having an extended acoustic characteristic life in a wide rotation speed range from high-speed rotation to low-speed rotation. A rolling bearing comprising a plurality of rolling elements rotatably held between an inner ring and an outer ring via a retainer, wherein the retainer has at least a pocket and a peripheral edge of an opening in a radial direction. And a thickener selected from lithium salts of fatty acids not containing hydroxyl groups, lithium salts of fatty acids containing hydroxyl groups, and mixtures thereof, and a kinematic viscosity at 40 ° C. of 30 to 80 mm ^2. / Sec
And a base oil containing an ester oil as an essential component, and a grease composition encapsulated therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing, and more particularly to a rolling bearing which has improved cage sound at low temperatures and bearing acoustic performance at high temperatures, and has a longer life of acoustic characteristics from high speed to low speed rotation. About bearings.

[0002]

2. Description of the Related Art In recent years, air conditioners (air conditioners) have become more sophisticated and multifunctional. For example, after cooling down a room temperature in a short time by rapid cooling by high-speed operation,
It has been practiced to maintain a constant temperature during low-speed operation. At the time of low-speed operation, low-noise operation in which air blowing noise, motor rotation noise, and the like are suppressed is required. However, during low-speed operation, the cooling efficiency inside the device decreases, and the temperature of the bearing incorporated in the motor may rise to around 100 to 120 ° C. As a result, the grease sealed in the bearing deteriorates, causing noise. Further, in an outdoor unit used for an air conditioner, there may be a problem of bearing initial sound (cage sound) at the time of startup at a low temperature such as winter.

[0003] By the way, as a rolling bearing for supporting a rotating part of an air conditioner, for example, a ball bearing as shown in FIG. 12 is widely used. In this ball bearing, an inner race 2 having an inner raceway 1 on an outer peripheral surface and an outer race 4 having an outer raceway 3 on an inner peripheral surface are arranged concentrically, and the inner raceway 1 and the outer raceway 3 are arranged.
And a plurality of balls 5, 5 are provided rotatably via a retainer 6. The retainer 6 is called a corrugated press retainer. The retainer 6 is formed by connecting a pair of elements 9, 9 formed by corrugating a metal plate material in an annular shape with rivets 10, and pockets formed by recesses 8 a, 8 a thereof. 8, 8 hold balls 5, 5. In addition, the portion between the outer peripheral surface of the inner ring 2 and the inner peripheral surface of the outer ring 4 is filled or continuously supplied with grease so that vibration and noise are not generated in the ball bearing.
Prevent failures such as burn-in.

However, in the case of the above-described ball bearing incorporating the retainer 6, even if a required amount of grease is filled or supplied, vibration is induced in the retainer 6, and the ball incorporating the retainer 6 is mounted. In some cases, noise or vibration called cage noise may occur in the bearing. Such vibration of the retainer 6 is based on the sliding friction between the balls 5 and 5, which are rolling elements, and the retainer 6 due to the large amount of movement of the retainer 6 relative to the balls 5 and 5. Occur. Therefore, in order to suppress the occurrence of such cage noise, conventionally, the gap between the inner peripheral surfaces of the pockets 8, 8 of the cage 6 and the rolling surfaces of the balls 5, 5 is reduced so that the ball 5, Although the amount of movement of the cages 6 with respect to 5 is reduced, a cage sound may be generated due to the shape of the inner peripheral surface of the cage 6.

The reason for this is shown in FIGS. 13 and 9 (B).
This will be described below. FIG. 9 is an enlarged cross-sectional view showing a portion corresponding to an inner peripheral surface of the retainer that holds the ball, and FIG.
Shows the structure of the present invention, and (B) shows the conventional structure. As shown, the opening periphery 17 of the pocket 8 of the cage 6
Has sharp (large curvature) corners 13, 13,
These corners 13 and 13 provide resistance to the flow of grease. Also, as shown by the dashed line in FIG. 9 (B), corners 15, 15 may also be present at the peripheral edge of the holding concave surface 11, and the corners 15, 15 may extend beyond the corners 13, 13 of the opening peripheral edge 17. The grease that tries to enter the pocket 8 is also scraped off at the corners 15 and 15 and is difficult to reach the interior of the pocket 8. Thus, these corners 13, 1
5, the gap 1 between the holding concave surface 11 and the rolling surface of the ball 5
4 does not take in a sufficient amount of grease, so that the frictional vibration of the sliding contact portion between the retainer 6 and the balls 5, 5 cannot be sufficiently suppressed, causing vibration and noise. In particular, as described above, in the outdoor unit used in the air conditioner, the cage sound at the time of startup at a low temperature such as in winter is remarkable.

[0006] On the other hand, as a grease conventionally sealed in a bearing of an air conditioner, lithium soap, lithium soap,
An ester grease composition using dioctyl sebacate (DOS), pentaerythritol (PET), or the like as a base oil, or a lithium complex grease composition added with polyoxyethylene ether is generally used. However, these grease compositions have excellent acoustic properties at the beginning of operation and at low temperatures,
On the other hand, there is a problem that the acoustic characteristics under high temperature deteriorate early.

[0007]

As described above, the conventional rolling bearing used in the air conditioner has a cage noise caused by the shape of the cage, and the grease composition sealed therein. Also, there is a problem that the acoustic characteristics of the object under high temperature deteriorate early. Therefore, the object of the present invention is to
Suppressed cage noise during startup at low temperatures, improved bearing acoustic characteristics at low and high temperatures, and extended the life of acoustic characteristics in a wide range of rotation speeds from high to low speed rotation. It is to provide a rolling bearing.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have developed a grease composition in which a cage is processed into a specific shape and the acoustic characteristics of a bearing at high temperatures are improved. By enclosing the object, it has been found that the acoustic characteristics over a wide temperature range and a rotational speed can be improved, including the sound of the cage at the time of starting at a low temperature, and arrived at the present invention. That is, an object of the present invention is a rolling bearing having a plurality of rolling elements rotatably held between an inner ring and an outer ring via a retainer, wherein the retainer has at least a pocket and a radial direction. And a thickener selected from a lithium salt of a fatty acid containing no hydroxyl group, a lithium salt of a fatty acid containing a hydroxyl group, and a mixture thereof, and a kinematic viscosity at 40 ° C. 30 ~
The rolling bearing is characterized in that a grease composition containing 80 mm ² / sec and a base oil containing an ester oil as an essential component is enclosed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a rolling bearing according to the present invention will be described in detail with reference to the drawings. The rolling bearing according to the present invention is characterized in that at least a part of a peripheral edge of an opening in a radial direction is chamfered at least in a pocket of a cage. In particular, a cage having a chamfered shape in the following (1) or (2) is preferable. (1) A retainer in which at least a part of the inner surface of each pocket is a convex surface having an arc-shaped cross section. (2) A cage in which at least a part of each pocket having a high frequency of contact with the rolling surface of the rolling element satisfies at least one of the following. The peripheral edge of the opening of each pocket is 1% of the outer diameter of the rolling element.
It is a convex surface having the above-described radius of curvature and having an arc-shaped cross section. An arcuate cross-section convex surface has a retaining surface peripheral edge between the opening peripheral edge of each pocket and the retaining surface, and the retaining surface peripheral edge has a radius of curvature of 10% or more of the outer diameter of the rolling element. It is.

Hereinafter, specific examples of preferred cages will be described.
FIG. 1 is a sectional view showing a first embodiment corresponding to the above (1), which is applied to a corrugated press retainer (see FIGS. 12 and 13). The retainer 25 includes a plurality of balls 5 as rolling elements, similarly to the above-described conventional corrugated press retainer.
In order to keep the rolling freely, the elements 26, 26, each of which is formed in a waveform, are combined to form an entire ring, and pockets 8 are provided at a plurality of positions in the circumferential direction. Each of the elements 26, 26 is formed by press-forming a metal plate material such as a steel plate into a corrugated shape. The cross-sectional shape of at least a portion constituting each pocket 8 is a beer barrel type or a rugby ball shape. Has a curved surface curved in a convex direction. Further, in the case of this example, the inner diameter of each pocket 8 is set to the outer peripheral side of the cage 25 (FIG. 1).
Is larger on the inner peripheral side (lower side in FIG. 1).

In the retainer 25 configured as described above,
By forming the inner surface of each pocket 8 as a convex surface having an arcuate cross section, a sufficient distance between the peripheral edges of the openings at both ends of each pocket 8 and the rolling surface of the ball 5 is ensured. As a result, during operation of the ball bearing, a lubricant such as grease existing around the pocket 8 easily enters between the inner surface of the pocket 8 and the rolling surface of the ball 5 as the ball 5 rolls. The sliding friction between the inner surface of each pocket 8 and the rolling surface of the ball 5 is reduced. The sliding friction between these two surfaces is also reduced by reducing the contact area between these two surfaces. That is, in the cage having the conventional structure shown in FIGS. 12 and 13, the contact state between these two surfaces is close to the surface contact, and relatively large sliding friction acts between these two surfaces. In the case of the example, the contact state between the two surfaces is close to a line contact or a point contact, the sliding friction between the inner surface and the rolling surface is reduced, and vibration and noise called retainer sound are hardly generated. Become.

FIG. 2 is a sectional view showing a second embodiment of the corrugated press holder, which also corresponds to the above (1). In the case of this embodiment, the outer peripheral side of each pocket 8 (see FIG. The inner diameter of the opening (upper side) and the inner circumference (lower side of FIG. 2) are made substantially equal. Further, of the pair of elements 26a, 26a constituting the retainer 25a, at least the inner surface of each pocket 8 is formed as a curved surface curved in a direction in which the rolling surface side of the ball 5 held in each pocket 8 becomes convex. I have. Therefore, in the case of the present example, the inner diameter of each pocket 8 is the smallest at the intermediate portion. Also in the case of the present embodiment configured as described above, the vibration and noise called the retainer sound hardly occurs due to substantially the same operation as the above-described first embodiment.

FIGS. 3 to 5 show the above (1), respectively.
The third to fifth embodiments corresponding to FIG. However, each of these examples is different from the first and second embodiments described above, and is applied to a crown type cage. This crown type retainer is made of synthetic resin, and has pockets 8, 8 for holding balls (not shown) at a plurality of circumferential positions of an annular main portion 7 as shown in FIG. 6. The pockets 8, 8 of the crown-shaped retainer 6a are provided on one side of a pair of elastic pieces 12, 12, which are spaced from each other in the main part 7, and in the axial direction of the main part 7 (FIG. 6).
The pair of elastic pieces 1 on one surface (the upper surface in FIG. 6)
Spherical concave portions 20, 2 provided in a portion between
0. The radius of curvature of the concave portions 20, 20 is
The radius of curvature is set slightly larger than the radius of curvature of the outer surface of the ball.
Form a holding concave surface. In addition, as synthetic resin, 4-6 nylon, 6-6 nylon, polyacetal resin, polyphenylene sulfide resin and the like are used.

In the third to fifth embodiments,
By chamfering the pockets 8, 8 of the crown-shaped cage 6a, the cage noise is reduced. That is, in the third embodiment shown in FIG.
Are curved surfaces curved in a direction in which the rolling surface side of the ball held in each pocket 8 is convex. Further, in the fourth embodiment shown in FIG. 4, the inner diameter of the opening on the outer peripheral side (upper side in FIG. 4) of each pocket 8 of the crown type retainer 27a is smaller than the outer diameter of the ball, and the inner peripheral side (FIG. The inner diameter of the opening is larger than the outer diameter. In the fifth embodiment shown in FIG. 5, only the inner and outer ends (upper and lower ends in FIG. 5) of each pocket 8 of the crown-shaped cage 27b are directed toward the ball rolling surface. The curved surface is curved in a convex direction. In each of the third to fifth embodiments, the first,
By virtue of substantially the same operation as in the second embodiment, vibration and noise called cage sound hardly occur. In particular, in the fifth embodiment shown in FIG. 5, the grease is held (accumulates) between the intermediate portion of the inner surface of each pocket 8 and the rolling surface of the ball. Lubrication is performed well, and generation of cage noise can be more reliably prevented.

FIGS. 7 and 8 correspond to the above (2).
It is sectional drawing which shows 6th Example, and applied to the corrugated press holder (refer FIG. 12, FIG. 13). The retainer 16 abuts a pair of elements 9 having recesses 8a constituting the pocket 8 with the recesses 8a aligned with each other, and connects them with rivets (not shown). By fixing, the whole is formed in an annular shape.
The pair of elements 9 is formed by press-forming a metal plate material such as a steel plate into a corrugated shape. In addition, a holding concave surface 11 having an arcuate cross-section as a holding surface and having a radius of curvature R11 slightly larger than the radius of curvature r of the rolling surface of the ball 5 is provided in the middle part of the inner surface of each pocket 8.

Further, the opening peripheral portions 17, 1
7 and the peripheral edge portion 1 of the holding concave surface 11 shown in FIG.
Corresponding portions 8 and 18, that is, the periphery of the holding surface are formed as convex surfaces 21 and 22 having an arc-shaped cross section, respectively. In addition, although the above-mentioned peripheral portions 18 and 18 are present in a part of the portion surrounded by the alternate long and short dash line showing the opening peripheral portions 17 and 17 in FIG. 7, they are omitted from the drawing. Here, the peripheral portions 17 and 17 are
In the case of 1, 21, the curvature radius R of the convex surfaces 21, 21
21 is 1% or more of the outer diameter 2r of the rolling surface of the ball 5 (R21 ≧ 0.
02r). When the peripheral portions 18, 18 of the holding concave surface 11 are convex surfaces 22, 22, the radius of curvature R22 of the convex surfaces 22, 22 is the outer diameter 2 of the rolling surface of the ball 5.
It is preferable that r is 10% or more (R22 ≧ 0.2r). When the radius of curvature R21 is less than 1% of the outer diameter of the rolling surface of the ball 5, the curvature of the opening peripheral portions 17, 17 of the pocket 8 is large, and this portion serves as resistance to the flow of grease, and It is difficult for grease to flow into the inside.
When the radius of curvature R22 is less than 10% of the outer diameter of the ball 5, the curvature of the convex surfaces 22, 22 is too large, and the grease that attempts to enter the pocket 8 beyond the opening peripheral portions 17, 17 is generated. It is difficult to reach the inside of the pocket 8 by being scraped off at the convex surfaces 22 and 22. Each of these convex surfaces 21,
The operation for forming 22 can be easily performed by a conventionally known processing method such as barrel processing and shot blasting.

According to the retainer 16 configured as described above, the displacement of the retainer 16 with respect to the ball 5 is reduced to a small value.
Even if the gap 14 between the rolling surface of the ball 5 and the holding concave surface 11 is made small, grease easily flows into the gap 14, and furthermore,
This grease easily enters the pocket 8. That is, as shown in FIG.
By making the convex surfaces 21 and 21 the edge-like corner portions 13 and 13 as shown in FIG. Therefore, the lubricant easily flows into the pocket 8. Furthermore, by forming the peripheral portions 18, 18 as the convex surfaces 22, 22, the corner portions 15, 15 as shown in FIG. 9B do not exist. For this reason, the grease is not scraped off by the corners 15, 15, and the grease is less likely to flow back from the inside of the pocket 8 to the outside, and it is easy to enter the inside of the pocket 8. As a result, the lubrication state of the sliding contact portion between the rolling surface of the ball 5 and the holding concave surface 11 of the cage 16 is improved. Further, due to the wedge effect due to the presence of the respective convex surfaces 21 and 22, a strong grease film is formed in the gap 14, the thickness of the gap 14 is hardly changed, and the ball 5 and the retainer 16 are hardly displaced. Become.

In this embodiment, the opening edge 1
Each of the convex portions 21 and 22 and the peripheral portions 18 and 18 of the holding concave surface 11 are convex surfaces 21 and 22, respectively. Performance is improved. In addition, each of the above parts 17,
Even if both 18 are convex surfaces 21 and 22, respectively,
Alternatively, even when only the peripheral portions 18 and 18 are the convex surfaces 22,
The absence of the corners 15, 15 prevents the corners 15, 15 from contacting the rolling surface of the ball 5. For this reason, it can prevent that a rolling surface and a large curvature part contact. When the rolling surface comes into contact with a portion with a large curvature, it is difficult for a sufficient oil film to be formed at the contact portion,
Vibration is likely to occur in this portion, but in the case of the present embodiment, vibration and noise due to such causes can be suppressed.
Further, the convex surfaces 21 and 22 do not necessarily need to be formed over the entire periphery of the pocket 8, but may be formed at a portion where lubricating oil is easily taken in. For example, only the ends 24, 24, which have a high frequency of contact with the ball 5, and are indicated by the chain-line circles in FIG.
Convex surfaces 21 and 22 having an arc-shaped cross section having the above-mentioned curvature radii R21 and R22.
Can also be formed. In this case, the convex surfaces 21, 2
2 can be processed by a mechanical polishing method such as buff polishing. This is the same in the first to fifth embodiments.

In order to confirm the effect of the chamfering of the cage, the cage 16 chamfered as described above and the conventional cage without chamfering (see FIG. 13) are incorporated into a ball bearing. A comparative test was performed to measure the frequency spectrum of the noise generated by each of the ball bearings. The ball bearing used in the experiment had an outer ring with an outer diameter of 35 mm and a width of 11 mm.
mm, inner ring inner diameter is 15mm, ball diameter is 6mm, ball number is 8
Individual. R21 was set to 0.1 mm for the product of the present invention and 0.05 mm for the conventional product. Further, R22 was 0.6 mm for the product of the present invention and 0.1 mm for the conventional product. FIG. 10 shows the results of experiments performed under such conditions as frequency spectra of the respective ball bearings. FIG.
At 0, the horizontal axis represents frequency and the vertical axis represents noise level. Among the two lines representing the measurement results, the solid line a represents the frequency spectrum of the noise generated by the ball bearing formed by using the cage 16 according to the present invention, and the two-dot chain line b represents the conventional cage. Respectively represent the frequency spectrum of the noise generated by the ball bearings configured using.
Note that, among the components constituting the respective ball bearings, the same (equivalent) components were used for the components other than the retainer. From FIG. 10, in the case of the ball bearing using the cage 16 according to the present invention, the peak of the frequency spectrum is small, and further, the unpleasant high-frequency components are drastically reduced.
It can be seen that the acoustic characteristics have been improved. Although the experimental results are not shown, similar tests were performed on the cages of the first to fifth embodiments shown in FIGS. 1 to 5, and it was confirmed that the cage sound could be similarly reduced. .

FIG. 11 is a sectional view showing a seventh embodiment corresponding to the above (2), which is applied to the crown type cage shown in FIG. The retainer 16a is made of a synthetic resin and is provided at an annular main portion 7 at a plurality of positions in the circumferential direction of the main portion 7, and holds the balls 5 which are rolling elements one by one inside the inside so as to freely roll. And a plurality of pockets 8 to be provided. Each pocket 8 has a pair of elastic pieces 12 arranged on the main part 7 at an interval from each other, and one surface in the axial direction of the main part 7 (upper surface in FIG. 11).
A concave portion 2 provided at a portion between the pair of elastic pieces 12.
0. The concave portion 20 is provided in the cage 1
6a is a spherical concave surface having a radius of curvature R20 slightly larger than the radius of curvature r of the rolling surface of the ball 5 to be held. The concave portion 20 and one side surface of the pair of elastic pieces 12 are a holding surface (corresponding to the holding concave surface 11 in the sixth embodiment described above). In addition, the opening peripheral portions 19, 19 of each pocket 8, which are surrounded by alternate long and short dash lines in the figure, are convex surfaces 23, 23 having an arc-shaped cross section. And this convex surface 23, 23
Is 1% or more (R23 ≧ 0.02r) of the outer diameter (= 2r) of the ball 5. The reason is as described in the sixth embodiment. In this embodiment, the convex surface 2 having an arc-shaped cross section is formed only on the opening peripheral portions 19 and 19.
3, 23. Other configurations and operations are the same as those in the sixth embodiment.

The rolling bearing constructed by incorporating the chamfered cage as described above is injected with the following grease composition and sealed with a suitable sealing member. The base oil used in the grease composition has an ester oil as an essential component. The ester oil is not particularly limited, but is a diester oil obtained from a reaction between a dibasic acid and a branched alcohol, an aromatic ester oil obtained from a reaction between an aromatic tribasic acid and a branched alcohol, and a polyhydric alcohol and a monobasic oil. Hindered ester oils obtained from acid reactions are preferably used. When heat resistance is taken into consideration, it is particularly preferable to use an aromatic ester oil or a hindered ester oil, which is selected alone or in combination. As diester oils, dioctyl adipate (DOA), diisobutyl adipate (DIBA), dibutyl adipate (DBA), dioctyl azelate (DOZ), dibutyl sebacate (D
BS), dioctyl sebacate (DOS), methyl acetyl ricinoleate (MAR-N) and the like. Examples of the aromatic ester oil include trioctyl trimellitate (TOTM), tridecyl trimellitate, and tetraoctyl pyromellitate.

Examples of the hindered ester oil include those obtained by appropriately reacting a polyhydric alcohol shown below with a monobasic acid. The monobasic acid reacted with the polyhydric alcohol may be used alone or in combination. Further, it may be used as a complex ester which is an oligoester of a polyhydric alcohol and a mixed fatty acid of a dibasic acid / monobasic acid. Examples of the polyhydric alcohol include trimethylolpropane (TMP), pentaerythritol (PE), dipentaerythritol (DPE), neopentyl prechol (NPG), 2-methyl-2-propyl-1,3-propanediol (MPPD). ) And the like. The monobasic acids, mainly monovalent fatty acids from C ₄ C ₁₈ are used. Specifically, for example, butyric acid, valeric acid, caproic acid, caprylic acid, enanthic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, mystyric acid, palmitic acid, tallow fatty acid, sularic acid, caproleic acid, undecylenic acid, Lindelic acid, tuzunic acid, physeteric acid, myristolic acid, palmitoleic acid, petroselinic acid,
Oleic acid, elaidic acid, asclepic acid, vaccenic acid, sorbic acid, linoleic acid, linolenic acid, savininic acid, ricinoleic acid and the like. The amount of ester oil
It contains at least 50 wt% of the total amount of the base oil. If the ester oil content is less than 50% by weight, sufficient high-temperature durability, especially at low speeds, cannot be obtained.

Further, the grease composition includes
Synthetic hydrocarbon oil, ether
Oil can be blended. As a synthetic hydrocarbon oil
Is a poly-α-olefin oil, α-olefin and ethylene
And co-oligomer synthetic oils. Ether oil
As diphenyl, triphenyl, tetraphenyl
C₁₂~ C ₂₀Phenyl derived from the (di) alkyl chain of
Ruether oil. Especially considering high temperature and high speed durability
For example, (di) alkyl polyphenyl ether oil is preferred
No. These compounding ratios are within 50 wt%.

Base oil viscosity: 40 ° C. Kinematic viscosity: 30-80 mm
² / sec, especially 50 to 80 mm ² / s
ec is preferred. When the kinematic viscosity is less than 30 mm ² / sec, the film-forming property is not sufficient especially at low speed rotation, and
^A high viscosity exceeding ² / sec is not preferable because a bearing cage noise is generated at the time of startup at a low temperature.

The thickener used in the grease composition is referred to as a lithium salt of a fatty acid containing no hydroxyl group (hereinafter referred to as lithium soap A) and a lithium salt of a fatty acid containing a hydroxyl group (hereinafter referred to as lithium soap B). ) Are used alone or in combination. Lithium soap B has a high affinity for the base oil due to the action of the hydroxyl group contained in the structure, has good dispersibility, and can improve the acoustic characteristics of the bearing to which the grease composition is applied. Further, by using lithium soap A in combination, the soap structure is more stable, a dense soap structure is obtained, and the durability under high temperature conditions is improved. When lithium soap A and lithium soap B are used as a mixture, lithium soap A is 0 to 70 watts.
It is preferable that lithium soap B is blended so as to be in the range of 30 to 100 wt%. In particular, lithium soap A is 0 to 60 wt%, and lithium soap B is 4 wt%.
It is preferable to be in the range of 0 to 100 wt%. Also,
The thickener is contained in the grease composition in an amount of 5 wt% or more and less than 20 wt%, preferably 5 to 18 wt%. If the thickener is less than 5 wt%, the consistency increases, the grease softens, and the grease leaks out of the bearing, failing to obtain sufficient acoustic characteristics. If it is at least 20 wt%, the torque and the acoustic characteristics at high temperatures will be poor.

The fatty acids of both lithium soaps A and B preferably have 12 to 24 carbon atoms, and specific compounds are shown below. Examples of lithium soap A include lithium laurate (C ₁₂ ), lithium myristate (C ₁₄ ), lithium palmitate (C ₁₆ ), and margaric acid (C
₁₇₎ Lithium stearate (C ₁₈₎ lithium, arachidic acid (C ₂₀₎ lithium, behenic acid (C ₂₂₎ lithium,
Examples thereof include lithium lignoceric acid (C ₂₄ ) and lithium tallow fatty acid, and preferred are lithium stearate and lithium tallow fatty acid. As lithium soap B, for example, lithium 9-hydroxystearate, 10
Lithium-hydroxystearate, lithium 12-hydroxystearate, lithium 9,10-dihydroxystearate, lithium ricinoleate, lithium ricinoelaidate and the like are preferable, and lithium 12-hydroxystearate is preferable.

The grease composition contains the above base oil and a thickener. However, as long as the preferable properties are not impaired, in addition to the base oil and the thickener, a rust inhibitor, an antioxidant, a metal inactive agent, and the like. Agents, extreme pressure agents, antiwear agents, viscosity index improvers and the like can be added alone or in combination of two or more. These may be any of known ones. For example, other thickeners such as metal soaps made of metal salts other than lithium, benton and silica gel; antioxidants such as amine type, phenol type, sulfur type and zinc dithiophosphate;
Extreme pressure agents such as chlorine-based, sulfur-based, phosphorus-based, zinc dithiophosphate, organic molybdenum; oil-based agents such as fatty acids and vegetable oils; rust inhibitors such as petroleum sulfonate, dinonylnaphthalene sulfonate, sorbitan esters; benzotriazole and nitrous acid A metal deactivator such as soda; a viscosity index improver such as polymethacrylate, polyisobutylene, and polystyrene may be added alone or in combination of two or more.

The present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples. Examples 1 to 6, Comparative Examples 1 to 5 Each grease composition was prepared by mixing a thickener and a base oil as shown in Tables 1 and 2. The total amount of lithium stearate, lithium 12-hydroxystearate (described as lithium 12-OH stearate in the table) and the base oil was 950 g,
To this, an antioxidant, a rust inhibitor, and a metal deactivator were added in a total amount of 50 g to obtain a grease composition having a total amount of 1000 g.
The base oil viscosity (40 ° C.) is also shown in the table.

[0029]

[Table 1]

[0030]

[Table 2]

Each grease composition is applied to a test bearing,
(1) The bearing acoustic test and (2) the bearing cage sound measurement were performed.

(1) Bearing Acoustic Endurance Test In Examples 1 to 6 and Comparative Examples 1 and 2,
A crown-shaped cage having an inner diameter of 6 mm, an outer diameter of 15 mm, and a width of 5 mm and chamfered as shown in the third embodiment was used.
In the case of ~ 5, a crown type cage with the same dimensions and no chamfer was used,
Each of them was subjected to rotary washing twice with petroleum benzene, allowed to stand at room temperature, dried, and completely degreased.
6). Then, 0.050 g of each grease composition was sealed in the test bearing using a syringe and sealed with a non-contact metal seal (Z type). Sixteen bearings were prepared for each grease composition, and mounted on a grease life tester shown in FIGS. In this grease life tester, a test bearing placed in a housing 28 is rotated by a motor 31 via a rubber belt 29 and a pulley 30. Then, the grease life tester was housed in a thermostatic chamber adjusted to 120 ° C.
It was rotated for 1000 hours at rpm and 5600 rpm (both in axial load 2 kgf). After 1000 hours, the bearing was taken out, and the acoustic characteristics of the bearing were examined according to the following evaluation criteria.

The acoustic measurement of the bearing is performed using an Anderon meter, and the acoustic characteristic is determined by comparing the Anderon value of the bearing immediately after the grease composition is sealed and the Anderon value of the bearing after 1000 hours of rotation. Was. The results of the determination are shown in Tables 1 and 2 above as “な し”, no decrease in acoustic characteristics, “△” and “×”.

(2) Measurement of bearing cage sound In Examples 1 to 6 and Comparative Examples 1 and 2, it was made of synthetic resin.
A crown type cage having an inner diameter of 8 mm, an outer diameter of 22 mm, and a width of 7 mm and chamfered as shown in the third embodiment was used.
In the case of ~ 5, a crown type cage with the same dimensions and no chamfer was used,
Each of them was washed twice with petroleum benzene, washed twice, allowed to stand at room temperature, dried and completely degreased (call number: 60).
8). Then, 0.16 g of each grease composition was sealed in the test bearing using a syringe, and sealed with a non-contact metal seal (Z type). Five bearings were prepared for each grease composition. The bearing was rotated at 1800 rpm and the cage sound at 0 ° C. and −10 ° C. was measured using a frequency analyzer. The results of the determination are shown in Tables 1 and 2 above, as “○” without generation of cage sound, “有 り” slightly with cage sound “△”, and “×” with large cage sound.

From the above test results, the bearings of Examples 1 to 6 have excellent acoustic characteristics at both low speed rotation and high speed rotation, and generate cage noise at low temperatures (0 ° C., -10 ° C.). It can be seen that it is practically preferable. On the other hand, the bearings of Comparative Examples 1 to 5 tend to have poor acoustic characteristics.
The generation of cage noise at low temperatures is also observed. Further, from Comparative Examples 1 and 2, the ester oil blending of the encapsulated grease composition,
When the base oil viscosity was out of the range of the present invention, it was confirmed that the retainer sound increased.

As described above, the rolling bearing of the present invention has been mainly described by taking a ball bearing as an example. However, the present invention is not limited to the ball bearing but can be applied to a roller bearing and the like.

[0037]

As described above, according to the rolling bearing of the present invention, the cage is chamfered to improve the inflow of the grease into the pocket, and the grease having excellent acoustic characteristics at high temperatures is enclosed. By doing so, the acoustic characteristics at low and high temperatures are improved, the life of the acoustic characteristics at high to low speed rotation is prolonged, and the generation of cage noise at low temperatures can be suppressed.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a first embodiment of a retainer incorporated in a rolling bearing of the present invention, and showing a part of the retainer in a state of holding a ball.

FIG. 2 is a view similar to FIG. 1, showing the second embodiment;

FIG. 3 is a view similar to FIG. 1, showing the third embodiment.

FIG. 4 is a view similar to FIG. 1, showing the fourth embodiment.

FIG. 5 is a view similar to FIG. 1, showing the fifth embodiment.

FIG. 6 is a perspective view for explaining a crown type cage.

FIG. 7 is a sectional view taken along the line AA of FIG. 8, showing the sixth embodiment.

FIG. 8 is a sectional view taken along line BB of FIG. 7;

9 is a cross-sectional view showing, in an enlarged manner, a portion corresponding to a portion C in FIG. 7 in each of the present invention example and the conventional example.

FIG. 10 is a diagram showing the results of a test performed to confirm the effects of the present invention.

FIG. 11 is a view showing a seventh embodiment of the present invention and corresponding to a section taken along line DD of FIG. 6;

FIG. 12 is a partially cutaway perspective view showing one example of a conventionally known ball bearing.

FIG. 13 is an enlarged cross-sectional view showing a state where a ball is held by the cage shown in FIG. 12;

FIG. 14 is a schematic view of an apparatus used for a bearing acoustic durability test.

FIG. 15 is a cross-sectional view of a main part for describing a rotation mechanism of the apparatus in FIG. 14;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inner raceway 2 inner race 3 outer raceway 4 outer race 5 ball 6, 6 a retainer 7 main part 8 pocket 8 a recess 9 element 10 rivet 11 retaining concave surface 12 elastic piece 13 corner 14 gap 15 corner 16, 16 a retainer 17 opening periphery Part 18 peripheral part 19 opening peripheral part 20 concave part 21, 22, 23 convex surface 24 end part 25, 25a retainer 26, 26a element 27, 27a, 27b retainer 28 housing 29 rubber belt 30 pulley 31 motor

Continued on the front page (72) Inventor Michiharu Naka 1-5-50 Kugenuma Shinmei, Fujisawa City, Kanagawa Prefecture Inside NSK Ltd. Inside the corporation

Claims (1)

[Claims] 1. A rolling bearing having a plurality of rolling elements rotatably held between an inner ring and an outer ring via a retainer, wherein the retainer has at least a pocket and a peripheral edge of an opening in a radial direction. A part of the part is chamfered, and a thickener selected from a lithium salt of a fatty acid containing no hydroxyl group, a lithium salt of a fatty acid containing a hydroxyl group and a mixture thereof, and a kinematic viscosity at 40 ° C of 30 to 80 mm ² / sec
And a base oil containing an ester oil as an essential component, and a grease composition encapsulated therein.