JP5101950B2 - Ball bearing - Google Patents

Description

  The present invention relates to a ball bearing, and relates to a ball bearing that can be applied to a bearing for electrical equipment of automobiles or auxiliary equipment by enclosing general-purpose grease or lubricating grease having a predetermined characteristic.

  In general, deep groove ball bearings and angular contact ball bearings are designed so that the radius of curvature of the rolling surface of the inner and outer rings is a constant value. In general-purpose products, the diameter of the rolling element is generally D, and the outer ring rolling surface If the radius of curvature is Ro and the radius of curvature of the inner ring rolling surface is Ri, then Ri = 0.51D and Ro = 0.52D. Further, a ball bearing for high-speed rotation is known in which Ro = Ri = 0.54D (Patent Document 1).

  For rolling bearings used in automobile electrical equipment or auxiliary equipment, as a means of solving the problem of suppressing cold noise during winter start, the composition of the lubricating grease has been adjusted, and the following lubricating greases have been adjusted: Compositions are known.

The base oil of the above lubricating grease has a pour point of −50 ° C. or less, a kinematic viscosity at 40 ° C. of 15 mm ² / s or more, and the thickener is a grease composition using a urea compound or a fluororesin or a combination of both. (Patent Document 2).

Further, the base oil an ether oil, ester oil or synthetic hydrocarbon oil or both in combination with the oil mixture, kinematic viscosity at 40 ° C. of the base oil is 15mm ² / s~200mm ² / s, poly as additives A grease composition containing (meth) acrylate is known (Patent Document 3).

  Furthermore, it contains a base oil, a thickener, and an additive, has a miscibility of not more than 300 at 25 ° C., and has an immiscibility of not more than 200 at −20 ° C. in heat and cold resistance. A grease composition is known (Patent Document 4).

JP-A-9-177795 JP 2005-290279 A JP 2006-169441 A JP 2006-225519 A

  However, the conventional rolling bearing described above has Ri = 0.51D, Ro = 0.52D, or Ro = Ri = 0.54D, and a specially prepared high-performance lubricating grease must be adopted. For example, there is a problem that it is impossible to reliably suppress the occurrence of cold abnormal noise when the automobile starts in winter.

  In other words, high-performance lubricating grease that can reliably suppress the occurrence of abnormal noise during cold requires high-level technology and materials required for preparation, and is demanded by customers who want to reduce the cost of rolling bearings. There is a problem that it is not possible to fully respond to the request.

  Therefore, the object of the present invention is to solve the above-mentioned problems, and to provide a ball bearing for automobiles that can sufficiently suppress the occurrence of cold abnormal noise at the start of winter without necessarily using a predetermined high-performance lubricating grease, Alternatively, a ball bearing that can similarly suppress the occurrence of abnormal noise during cold using a predetermined lubricating grease.

  In order to solve the above problems, in the present invention, the curvature radius Ro of the circular groove formed on the rolling surface of the outer ring in the ball bearing, and the curvature radius Ri of the circular groove formed on the rolling surface of the inner ring, However, the ball bearing is characterized by satisfying the relationship of the following formulas (I) and (II) with respect to the rolling element diameter D used in the ball bearing.

1.5 ≦ | 100 (Ro / D-Ri / D) | (I)
100 (Ro / D + Ri / D) <104 (II)

  The ball bearing of the present invention configured as described above is a general-purpose lubrication by satisfying a predetermined relationship that does not exist in the curvature radius of the circular groove formed on the rolling surface of the outer ring and the inner ring of the ball bearing. Even if grease is used, no noise is generated during cold start in winter.

  By providing a predetermined difference in the radius of curvature of the circular grooves formed on the rolling surfaces of the outer ring and the inner ring, the circular grooves on either or both of the inner and outer rings can be provided without impairing the function of the normal rolling surface. It is considered that a minute space or oil passage is formed to temporarily hold the required amount of lubricating grease for start-up lubrication, or lead to the lubrication point. A ball bearing that can be sufficiently suppressed can be configured.

  If a ball bearing that satisfies the relations of the formulas (I) and (II) in the above and further satisfies the relation of the following formula (III) is obtained, a ball bearing that can more reliably suppress the occurrence of cold abnormal noise is obtained.

50 <100 Ri / D <50.5 <100 Ro / D <54 (III)
If it is a ball bearing which has such a preferable characteristic, it will become a ball bearing sufficiently excellent also as a ball bearing used for the electrical equipment of an automobile, or an auxiliary machine.

Further, in order to obtain a ball bearing that can sufficiently suppress the occurrence of abnormal noise during cold, lubricating grease is prepared, that is, a grease composition containing a base oil and a thickener, and the base oil has a pour point. Is a grease composition (hereinafter referred to as “thickener”) having a viscosity of not more than −50 ° C. and a kinematic viscosity at 40 ° C. of 15 mm ² / s or more, and the thickener is at least one compound selected from urea compounds and fluororesins. It is preferable to employ abbreviated as grease composition A).

Further, for the same reason, as a lubricating grease, a grease composition containing a base oil, a thickener and an additive, wherein the base oil is at least one selected from ether oil, ester oil and synthetic hydrocarbon oil. It comprises oil, the is the kinematic viscosity of 15mm ² / s~200mm ² / s at 40 ° C. of the base oil, the additive is a poly (meth) grease composition comprising acrylate (hereinafter, the grease composition B and abbreviations Is more preferable.

  For the same reason, the lubricating grease contains a base oil, a thickener, and an additive, has a miscibility of not more than 300 at 25 ° C., and an immiscibility of not more than 200 at −20 ° C. It is more preferable to employ a heat-resistant and cold-resistant abnormal sound grease composition (hereinafter abbreviated as grease composition C).

  In the present invention, the curvature radius Ro of the circular groove formed on the rolling surface of the outer ring in the ball bearing and the curvature radius Ri of the circular groove formed on the rolling surface of the inner ring satisfy the predetermined relationship. This is a ball bearing for automobiles that can sufficiently suppress the occurrence of cold noise at the start of winter without necessarily using the specified high-performance lubrication grease. There is an advantage that it becomes a ball bearing which can suppress generation.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
As shown in FIGS. 1 and 2, the first embodiment is a deep groove ball bearing in which a rolling element 4 made of a steel ball held by a cage 3 between an inner ring 1 and an outer ring 2 is interposed. The radius of curvature Ro of the circular groove 2a formed on the running surface and the radius of curvature Ri of the circular groove 1a formed on the rolling surface of the inner ring 1 are relative to the rolling element diameter D of the steel ball used in this ball bearing. The circular groove shape is formed so as to satisfy the relationship of the mathematical expressions (I) and (II).

1.5 ≦ | 100 (Ro / D-Ri / D) | (I)
100 (Ro / D + Ri / D) <104 (II)

  When the absolute value of 100 (Ro / D-Ri / D) represented by Formula I is smaller than 1.5, both the inner ring and outer ring circular grooves are in contact with the rolling element with the same contact area, and lubrication grease is used at the start. It is considered that there is no gap for efficiently flowing the water, and such an effect is eliminated, and the effect of suppressing cold noise is insufficient as in the test results described later.

Further, when the value of 100 (Ro / D + Ri / D) represented by the formula II is larger than 104, the required action of the present invention is lost, and the effect of suppressing cold abnormal noise is not as shown in the test results described later. It will be enough.
Further, it is preferable that the ball bearing satisfy the relations of the mathematical expressions (I) and (II) as described above and further satisfy the relation of the following mathematical expression (III).
50 <100 Ri / D <50.5 <100 Ro / D <54 (III)
In order to balance the contact surface pressure, it is preferable to make the curvature radius Ri of the inner ring smaller than the curvature radius Ro of the outer ring. Further, as is clear from the test results described later, the occurrence of abnormal noise during cold can be more reliably suppressed by setting the inner ring groove curvature to less than 50.5%. However, of course, the groove curvature cannot be made smaller than 50%.

  As shown in FIG. 2, in the deep groove rolling bearing in which various types of lubricating grease G are enclosed, an annular seal member 5 is attached to the inner ring 1 or the outer ring 2, and both axial ends of the inner ring 1 and the outer ring 2 are sealed. A lubricating grease G is sealed around at least the rolling elements 4 in the sealed bearing. The illustrated seal member 5 is exemplified by a member in which an outer peripheral edge is fixedly supported on an outer ring and a seal lip is formed on the inner peripheral edge.

Next, the grease composition A used in the present invention will be described.
The grease composition A is a grease composition containing a base oil and a thickener, and the base oil has a pour point of −50 ° C. or lower and a kinematic viscosity at 40 ° C. of 15 mm ² / s or higher. And the thickener is at least one compound selected from a urea compound and a fluororesin.

  The penetration degree of the grease composition A is preferably 250 to 350, and the base oil is preferably at least one oil selected from PAO oil and perfluoroether oil. The pour point is a value measured by a method defined in JIS K2269, and the penetration degree is a 60-times penetration value measured by a method defined in JIS K2220.

  It is considered that the blending of the above base oil prevents an increase in the viscosity of the grease composition A during cold weather, and suppresses the occurrence of oil film unevenness on the bearing raceway surface, thereby increasing the cold noise prevention effect.

As the base oil, a mineral oil, a synthetic oil, or a mixed oil used for general-purpose grease can be used as long as the above pour point and kinematic viscosity conditions are satisfied. A pour point depressant such as polymetacrete may be added, and in order not to lower the lubrication performance and lubrication life at high temperature and high speed, the kinematic viscosity at 40 ° C. is a high viscosity of 30 mm ² / s or more. preferable.

  Examples of mineral oils include paraffinic mineral oils and naphthenic mineral oils, and examples of synthetic oils include synthetic hydrocarbon oils, ether oils, ester oils, and fluorine oils.

PAO oil or the like as the synthetic hydrocarbon oil, dialkyl diphenyl ether oil, alkyl triphenyl ether oil, alkyl tetraphenyl ether oil or the like as the ether oil, diester oil, polyol ester oil or complex ester oil thereof as the ester oil, An aromatic ester etc. can be mentioned.
Moreover, perfluoropolyether oil can be mentioned as fluorine oil.

  Among these, in consideration of lubrication performance at high temperature and high speed and lubrication life, it is preferable that synthetic hydrocarbon oil, alkyldiphenyl ether oil, ester oil, and synthetic oil of fluorine oil are contained, PAO oil of synthetic hydrocarbon oil and It is particularly preferable that at least one oil selected from perfluoroether oils of fluorine oil is contained.

Examples of the thickener include urea compounds, fluororesin powders, and mixtures thereof. It is preferable to use the urea compound as a thickener in the synthetic oil and the fluororesin powder as the thickener in the perfluoropolyether oil, respectively. The urea compound is preferably a diurea having two urea bonds in the molecule as shown in Chemical Formula 1 below.

(In the formula, R ₁ and R ₃ are an aromatic hydrocarbon group having 6 to 12 carbon atoms, an aliphatic hydrocarbon group having 6 to 20 carbon atoms, and an alicyclic hydrocarbon group having 6 to 20 carbon atoms. R ₁ and R ₃ may be the same or different, and R ₂ represents an aromatic hydrocarbon group having 6 to 12 carbon atoms.

  Fluororesin that can be used to increase perfluoropolyether oil can use powders that have high affinity with perfluoropolyether oil and have high-temperature stability, and polytetrafluoroethylene (PTFE) has excellent high-temperature stability. Therefore, it is preferable.

  The blending ratio of the thickener is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the total amount of base oil and thickener. If it is less than 5 parts by weight, it becomes a liquid having a low viscosity and easily leaks, making it difficult to seal the bearing. On the other hand, if it exceeds 50 parts by weight, it will solidify to a consistency of 100 or less, so that it will not be practical as a grease for bearings.

  The blending degree of the grease composition A is preferably in the range of 250 to 350. If it is less than 250, the lubricating performance at a low temperature is deteriorated, and if it exceeds 350, the grease composition tends to leak, which is not preferable.

  The grease composition A of the invention comprises the above base oil and thickener as essential components, and further includes an extreme pressure agent, an antioxidant, a rust inhibitor, a metal deactivator, an oil agent, and the like. Conventional grease additives may be further blended.

Next, the grease composition B used in the present invention will be described.
The grease composition B includes a base oil, a thickener, and an additive, and the base oil includes at least one oil selected from ether oils, ester oils, and synthetic hydrocarbon oils. Kinematic viscosity at 40 ° C. of the base oil is 15mm ² / s~200mm ² / s, additive it is preferable to adopt those containing poly (meth) acrylate.

  The poly (meth) acrylate is polymethacrylate, polyacrylate, or a mixture of polymethacrylate and polyacrylate, and such poly (meth) acrylate is based on the total amount of the base oil and the thickener. It is preferable that 3 to 10% by weight is blended.

  The additive is preferably a poly (meth) acrylate added with zinc dithiophosphate, and the thickener is preferably a urea compound as represented by the formula 1 above. . As an example of a method for producing a urea compound, it can be obtained by reacting a diisocyanate compound with an amine compound equivalent to an isocyanate group. In addition to diurea, polyurea and the like can also be used.

  The blending degree of the grease composition B is preferably in the range of 150 to 400. If it is less than 150, the lubricating performance at a low temperature is deteriorated, and if it exceeds 400, the grease composition tends to leak, which is not preferable.

  The blending ratio of the base oil is preferably 50 to 95 parts by weight with respect to 100 parts by weight of the total amount of the base oil and the thickener. When the blending ratio of the base oil is less than 50 parts by weight, the grease is hard and the lubricity at low temperatures is poor. On the other hand, if it exceeds 95 parts by weight, it becomes soft and easily leaks.

  The blending ratio of the thickener is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the total amount of the base oil and the thickener. If it is less than 5 parts by weight, it becomes a liquid having a low viscosity and easily leaks, making it difficult to seal the bearing. On the other hand, if it exceeds 50 parts by weight, it will solidify to a consistency of 100 or less, so that it will not be practical as a grease for bearings.

  The grease composition B contains the above base oil and thickener as essential components, and further contains poly (meth) acrylate, and further includes an extreme pressure agent, an antioxidant, a rust inhibitor, a metal deactivator, Conventional grease additives such as oiliness agents can be further blended.

  In the grease composition B, the blending ratio of the additives is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the total amount of the base oil and the thickener. When the blending ratio of the additive is less than 0.1 parts by weight, the effect of adding the additive is poor, and when it exceeds 20 parts by weight, the grease is softened and easily leaks.

Next, the grease composition C used in the present invention will be described.
Grease composition C is a heat and cold resistant noise composition used in rolling bearings, and includes a base oil, a thickener, and an additive, and has a miscibility of 300 or less at 25 ° C. The unmixed penetration at −20 ° C. is preferably 200 or more.

  As a thickener, it is preferable to contain the urea compound shown by said Chemical formula 1. For the measurement of the consistency, a method defined in JISK2220 is adopted.

  Grease composition C is a grease composition that has achieved a long life at high temperatures by adjusting the blending consistency at 25 ° C. Further, by adjusting the non-mixing consistency at −20 ° C., By preventing the increase in the viscosity of the grease composition and suppressing the occurrence of oil film unevenness on the bearing raceway surface, the effect of preventing cold noise is increased.

  Grease composition C uses PAO oil, GTL oil synthesized by Fischer-Tropsch method and other additives such as viscosity index improvers such as polymethacrylate to improve the base oil viscosity index. Is obtained by blending.

The base oil that can be used is a mineral oil, a synthetic oil or a mixed oil usually used for grease. Synthetic hydrocarbon oils that have cold noise resistance are essential components to achieve both cold-proof noise resistance and high-temperature and high-speed durability, and either ether oil or ester oil that has excellent high-temperature and high-speed durability resistance. Is preferably blended. Among these, it is preferable to use PAO oil as the synthetic hydrocarbon oil, alkyl diphenyl ether oil as the ether oil, and polyol ester oil as the ester oil.
Further, high temperatures, for lubrication performance and lubrication life at a high speed is not lowered, it is preferable that the kinematic viscosity of the base oil at 40 ° C. is 15mm ² / s~200mm ² / s.

As a thickener, it contains a urea compound as an essential component, but in order to achieve both noise resistance during cold resistance and high temperature resistance at high temperature, an aliphatic amine that has noise resistance during cold resistance and high temperature resistance and high speed durability. It is preferable to use an alicyclic amine excellent in properties and an aromatic amine in combination.
As an example, octylamine can be cited as an aliphatic amine, cyclohexylamine as an alicyclic amine, and p-toluidine as an aromatic amine.

  The heat- and cold-resistant abnormal sound grease composition C contains the above-described base oil and thickener as essential components. Further, as well-known additives, extreme pressure agents, antioxidants, rust inhibitors, metals Additives for grease such as an inactivating agent and an oily agent can be blended.

  The blending ratio of the additive in the grease composition C is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the total amount of the base oil and the thickener. If the blending ratio of the additive is less than 0.1 parts by weight, the effect of adding the additive is poor, and if it exceeds 20 parts by weight, the grease composition C is softened and easily leaks.

  The blending ratio of the base oil is preferably 50 to 95 parts by weight with respect to 100 parts by weight of the total amount of the base oil and the thickener. When the blending ratio of the base oil is less than 50 parts by weight, the grease is hard and the lubricity at low temperatures is poor. On the other hand, if it exceeds 95 parts by weight, it becomes soft and easily leaks.

  The blending ratio of the thickener is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the total amount of the base oil and the thickener. If it is less than 5 parts by weight, it becomes a liquid having a low viscosity and easily leaks, making it difficult to seal the bearing. On the other hand, if it exceeds 50 parts by weight, it will solidify to a consistency of 100 or less, so that the grease composition C for sealing a bearing will not be practical.

  Ball bearings filled with lubricating grease such as the grease compositions A, B, and C as described above are used for fan coupling devices, alternators for automotive electrical equipment and accessories, belt tensioners for automotive accessory drive belts, and accessory drive. The present invention can be applied to all electric auxiliary equipment for automobiles such as belt pulleys, electromagnetic clutches and fan clutches.

  The fan coupling device, in which the fan supported by the ball bearing rotates, changes the rotation speed of the fan according to the temperature change, so that warm-up is accelerated and cooling water is not overcooled, effectively cooling the engine can do. When the engine temperature is low, the fan is equivalent to being disconnected from the drive shaft, and when the engine temperature is high, it is equivalent to being connected. Thus, the ball bearing is used in a wide temperature range from a low temperature to a high temperature and in a wide rotation speed range.

  In the alternator, a rotor rotating shaft, on which a rotor is mounted, is rotatably supported by a pair of ball bearings on a pair of frames forming a housing that is a stationary member. The rotor rotation shaft is transmitted by a belt to a pulley attached to the tip of the rotor rotation shaft, and is driven to rotate by rotational torque. Since the pulley is attached to the rotor rotation shaft in a cantilever state, and vibration is also generated as the rotor rotation shaft rotates at high speed, the ball bearing that supports the pulley side in particular receives a severe load.

An idler pulley used for an accessory driving belt of an automobile includes a pulley body and a grease-filled ball bearing such as a single-row deep groove ball bearing fitted to the inner diameter of the pulley body.
As described above, in automobile electrical equipment or auxiliary equipment, ball bearings are used under severe conditions in a wide temperature range and a wide rotation speed range from a low temperature to a high temperature.

[Examples 1 and 2 and Comparative Examples 1 to 3]
In a deep groove ball bearing (NTN 6203), the circular groove formed on the rolling surface of the outer ring has a radius of curvature of 100% to the ball diameter = 100 Ro / D, and the circular groove formed on the rolling surface of the inner ring. 100 parts ratio = 100 Ri / D with respect to the ball diameter is prepared as shown in Table 1, and a grease composition having predetermined characteristics is prepared from the following raw materials. 9g was sealed in the bearing of each test example, placed in a low temperature bath at -50 ° C for a certain period of time, then taken out, attached to a bearing rotating device installed at room temperature, and when the bearing temperature reached -20 ° C, radial The sample was rotated at a rotational speed of 2700 rpm under a load of 127 N, and the presence or absence of cold noise was confirmed by hearing.
Each example bearing test product (number of 10 pieces) was tested 7 times (10 × 7 = 70 times), and at that time, the cold noise was evaluated by the ratio (%) of the number of cold noises generated, The evaluation results are shown in Table 1. In Table 2, the variable values on the right side or the left side of the adjusted formulas I and II of the tested ball bearings are shown.
In the above grease composition, the base oil is an ether-based synthetic oil, aromatic diurea is used as a thickener, the base oil dynamic viscosity (40 ° C.) is 123.0 mm ² / s, and the base oil dynamic viscosity ( 100 ° C.) is 15.0 mm ² / s, and the consistency is 300.

  As is clear from the results of Tables 1 and 2, the value of 100 Ro / D (hereinafter referred to as the outer ring groove curvature) is set to a fixed value of 53%, and the value of 100 Ri / D (hereinafter referred to as the inner ring groove curvature). When the inner ring groove curvature is smaller, the incidence of cold abnormal noise is lower, and it was not generated at 50.5% as in Example 1. It has also been found that the occurrence of cold abnormal noise can be suppressed by setting the inner ring groove curvature to less than 50.5%.

  On the other hand, when the inner ring groove curvature was fixed to 50.5%, no cold noise was generated at the outer ring groove curvature of 53% (Example 1), but slightly at 50.5% (Comparative Example 1). Occurred. Further, when the inner ring groove curvature was fixed at 52%, it did not occur at the outer ring groove curvature of 50.5% (Example 2), but it occurred at a high probability at 53% (Comparative Example 3). From this, it can be seen that when the difference between the inner and outer ring groove curvatures is greater than 1.5, the cold noise suppression effect is excellent.

Further, it can be seen that the bearing in which abnormal noise is generated with a high probability has a groove curvature sum of 104% or more of the inner and outer rings, and that the sum of curvature is less than 104% is a high condition for suppressing noise.
From the above results, it was possible to suppress the occurrence of abnormal noise during cold without relying on the enclosed grease.

Exploded parts sectional view showing the main part of the ball bearing, showing the embodiment Sectional view of a ball bearing filled with lubricating grease, showing an embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 1a, 2a Circular groove 2 Outer ring 3 Cage 4 Rolling element 5 Seal member G Lubrication grease

Claims (4)

The radius of curvature Ro of the circular groove formed on the rolling surface of the outer ring in the ball bearing and the radius of curvature Ri of the circular groove formed on the rolling surface of the inner ring are relative to the rolling element diameter D used in this ball bearing. A ball bearing that satisfies the following mathematical formulas (I) , (II), and (III) , and that is used in electrical equipment or auxiliary equipment for automobiles by enclosing lubricating grease .
1.5 ≦ | 100 (Ro / D-Ri / D) | (I)
100 (Ro / D + Ri / D) <104 (II)
50 <100 Ri / D <50.5 <100 Ro / D <54 (III) The lubricating grease is a grease composition containing a base oil and a thickener, and the base oil has a pour point of −50 ° C. or lower and a kinematic viscosity at 40 ° C. of 15 mm ² / s or higher. the thickener ball bearing according to claim 1 Ru least one compound der selected from urea compounds and fluorocarbon resins. The lubricating grease is a grease composition containing a base oil, a thickener, and an additive, wherein the base oil contains at least one oil selected from an ether oil, an ester oil, and a synthetic hydrocarbon oil, kinematic viscosity at 40 ° C. oil is 15mm ² / s~200mm ² / s, the ball bearing of claim 1 wherein the additive is you comprising a poly (meth) acrylate. The lubricating grease contains a base oil, a thickener, and an additive, has a miscibility of not more than 300 at 25 ° C., and an immiscibility of not more than 200 at −20 ° C. The ball bearing according to claim 1, which is an abnormal sound grease composition.

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