JP2008169920A - Greased bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a greased bearing capable of being made advantageous against rolling fatigue of a rolling contact surface and running on a shoulder by reducing bearing pressure applied to the rolling contact surface, and becoming advantageous in terms of peeling by heat generation and slide. <P>SOLUTION: This greased bearing is provided with: an outer ring 23 having a raceway groove 22 on the inner peripheral surface; an inner ring 25 having a raceway groove 24 on the outer peripheral surface; rolling elements 27 rollably interposed between the raceway groove 22 of the outer ring 23 and the raceway groove 24 of the inner ring 25; and a cage 26 holding the rolling elements 27. In the raceway grooves 22 and 24 of the outer ring 23 and the inner ring 25, the curvature radii R1 and R3 of groove bottom parts 22a and 24a are set equal to the radius R of the rolling element 27. The curvature radii R2 and R4 of groove openings 22b and 24b are set larger than the curvature radii R1 and R3 of the groove bottom parts 22a and 24a. The groove bottom parts 22a and 24a and the groove openings 22b and 24b are formed into a combined groove curvature shape formed by combining them as a smoothly continuing circular arc, and the groove openings 22b and 24b are used as parts without contact with the rolling elements. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease-filled bearing, and in particular, electrical auxiliary equipment such as an alternator (automotive alternator for automobiles), a car air conditioner, an ABS (anti-lock brake system), a fan clutch, a starter, an electronic slot valve, and an idle speed control valve. The present invention relates to a grease-filled bearing used in the above.

  As shown in FIG. 4, the conventional grease-sealed bearing includes an outer ring 3 having a raceway surface 2 on an inner peripheral surface, an inner ring 5 having a raceway surface 4 on an outer peripheral surface, and a space between the raceway surface 2 and the raceway surface 4. A plurality of rolling elements (balls) 7 provided so as to be freely rotatable, a cage 6 interposed between the outer ring 3 and the inner ring 5 and supporting the ball 7, and a seal member fixed to the outer ring 3 8. And the grease composition G is enclosed at least around the rolling elements 7.

  Further, in the conventional grease-filled bearing, the groove radius of curvature of the inner and outer rings is constant, and is formed with a single (same) diameter. Therefore, it was an alternative design to reduce the curvature to be advantageous for surface pressure or to increase the curvature to be advantageous for climbing the shoulder. Here, the climbing on the shoulder means that the ball 7 rides on the shoulders 5a and 3a of the inner ring 5 or the outer ring 3, and if this shoulder climbing occurs, the surface of the ball 7 or the raceway surfaces 2 and 4 is roughened or peeled off. Or the like may occur, causing a decrease in the life of the ball bearing.

Therefore, conventionally, like the pulley support device for a compressor of Patent Document 1, only the curvature of the inner ring is made a composite curvature in a three-point contact ball bearing, preventing shoulder climbing and applying excessive surface pressure to the rolling surface. There is something that prevents things.
International Publication W02003 / 071412

  However, if one raceway groove and rolling surface are in contact at multiple points, such as a three-point contact or a four-point contact ball bearing, heat generation will increase, and there will be as many slip spots as there are contact surfaces. There is a problem that peeling is likely to occur.

  Further, in a compressor pulley support device or the like, there is often an offset in which the center of the radial load applied from the belt to the driven pulley and the center position of the bearing are shifted in the axial direction. When used in such a state where an offset has occurred, in the case of three-point contact or four-point contact, the sliding rate of the rolling element increases, and lubrication failure occurs and brittle peeling is likely to occur at the portion where the slip occurs. . Here, brittle exfoliation is exfoliation which is a main factor for hydrogen embrittlement of a metal material due to hydrogen intrusion into steel.

  In view of the above problems, the present invention can reduce the surface pressure applied to the rolling surface of the rolling element from the inner ring and the outer ring, and can also be advantageous for rolling-up rolling fatigue against shoulder climbing, and also due to heat generation and sliding. Provided is a grease-filled bearing that is advantageous in terms of peeling.

The grease-enclosed bearing of the present invention includes an outer ring having a raceway groove on an inner peripheral surface, an inner ring having a raceway groove on an outer peripheral surface, and a rolling element that is rotatably interposed between the raceway groove of the outer ring and the raceway groove of the inner ring. And a grease-sealed bearing comprising a grease composition and a cage that holds the rolling elements,
In each raceway groove of the outer ring and inner ring, the radius of curvature of the groove bottom is set to be the same as the radius of the rolling element, the radius of curvature of the groove opening is made larger than the radius of curvature of the groove bottom, and the groove bottom and groove opening As a composite groove curvature shape that combines the two as smooth continuous arcs, a groove opening portion having a large curvature radius is used as a non-contact portion of the rolling element.

  According to the grease-filled bearing of the present invention, in each raceway groove of the outer ring and the inner ring, the radius of curvature of the groove bottom is set to be the same as the radius of the rolling element, and the radius of curvature of the groove opening is larger than the radius of curvature of the groove bottom. Since it is made large, even when a high moment load is applied, it becomes difficult for the ball as the rolling element to ride on the shoulders of the outer ring and the inner ring, and it is possible to prevent excessive surface pressure from acting on the rolling contact portion. Moreover, there is one contact point between the raceway groove of the outer ring and the rolling element, one contact point between the raceway groove of the inner ring and the rolling element, and two contact points of the rolling element. Further, since the groove bottom and the groove opening are formed as a smoothly continuous arc, the rolling of the rolling element becomes smooth.

  The grease composition is formed by adding an additive to a base grease comprising a base oil and a thickener, and the additive contains at least one aluminum-based additive selected from aluminum powder and an aluminum compound. And the compounding ratio of this aluminum type additive is 0.05-10 weight part with respect to 100 weight part of base grease.

  By compounding the aluminum-based additive, the aluminum compound reacts on the frictional wear surface or the newly formed metal surface exposed by wear, and an aluminum coating is formed on the bearing raceway surface together with iron oxide. And the iron oxide and aluminum film produced | generated on the bearing raceway surface can suppress generation | occurrence | production of hydrogen by decomposition | disassembly of a grease composition, and can prevent the specific peeling | exfoliation by hydrogen embrittlement.

  The aluminum compound is preferably at least one compound selected from aluminum carbonate and aluminum nitrate, the thickener is preferably a urea-based thickener, and the base oil is an alkyl diphenyl ether oil. And at least one oil selected from poly-α-olefin oils.

  In the grease-filled bearing of the present invention, even when a high moment load is applied, it is difficult for the ball to ride on the shoulders of the outer ring and the inner ring, and it is possible to prevent an excessive surface pressure from acting on the rolling contact portion. For this reason, the rolling fatigue life of the bearing can be ensured while suppressing the inclination of the outer ring with respect to the inner ring, and the durability of the bearing can be ensured. In addition, the number of contact points of the rolling elements (balls) is reduced to two, and the rolling of the rolling elements is smooth, so that generation of peeling friction due to heat generation and sliding can be effectively prevented, and the torque becomes low.

  Further, as described above, an aluminum oxide film is formed on the steel surface due to the effect of the aluminum-added grease, and brittle peeling can be prevented by preventing activation of the raceway surface due to metal contact. Thus, the brittle peel resistance of the bearing used for the electrical accessory can be improved by the combination of the groove shape and the aluminum-added grease.

  An embodiment of a grease-sealed bearing according to the present invention will be described with reference to FIGS.

  FIG. 1 shows a grease-filled bearing used in an electrical accessory. Examples of the electric auxiliary equipment include an alternator (automotive alternator for automobile), a car air conditioner, an ABS (anti-lock brake system), a fan clutch, a starter, an electronic slot valve, an idle speed control valve, and the like.

  The grease-filled bearing includes an outer ring 23 having a raceway groove (track surface) 22 on an inner peripheral surface, an inner ring 25 having a raceway groove (track surface) 24 on an outer peripheral surface, and between the raceway groove 22 and the raceway groove 24. A plurality of rolling elements provided as a rolling element 27, a retainer 26 that is interposed between the outer ring 23 and the inner ring 25 and supports the ball 27, and a seal member 28 that is fixed to the outer ring 23. With. The grease composition G is sealed at least around the rolling elements 27.

  As shown in FIG. 2, in the raceway groove 22 of the outer ring 23, the curvature radius R1 of the groove bottom 22a is set to be the same as the radius R of the rolling element 27, and the curvature radius R2 of the groove opening 22b is set to the curvature of the groove bottom 22a. The radius of curvature is larger than the radius R1, and the groove bottom portion 22a and the groove opening 22b are combined into a complex groove curvature shape that is combined as a smoothly continuous arc. For this reason, as shown in FIG. 1, the groove opening 22 b becomes a rolling element non-contact portion that does not contact the rolling element 27. The groove opening 22b is a portion near the shoulder 23a of the raceway groove 22.

  As shown in FIG. 3, in the raceway groove 24 of the inner ring 25, the radius of curvature R3 of the groove bottom 24a is set to be the same as the radius R of the rolling element 27, and the radius of curvature R4 of the groove opening 24b is set to the curvature of the groove bottom 24a. The radius of curvature is larger than the radius R3, and the groove bottom portion 24a and the groove opening 24b are combined into a complex groove curvature shape that is combined as a smoothly continuous arc. For this reason, as shown in FIG. 1, the groove opening 24 b becomes a rolling element non-contact portion that does not contact the rolling element 27. In this case, the curvature radius R4 of the groove opening 24b of the raceway groove 24 of the inner ring 25 is set smaller than the curvature radius R2 of the groove opening 22b of the outer ring 23. The groove opening 24b is a portion near the shoulder 25a of the raceway groove 24.

  The grease composition comprises a base grease comprising a base oil and a thickener, and the additive contains at least one aluminum-based additive selected from aluminum powder and an aluminum compound. The mixing ratio of the aluminum-based additive is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease.

  The aluminum-based additive added to the grease composition G of the present invention is at least one selected from aluminum powder and an aluminum compound. Aluminum compounds include aluminum carbonate, aluminum sulfide, aluminum chloride, aluminum nitrate and its hydrate, aluminum sulfate, aluminum fluoride, aluminum bromide, aluminum iodide, aluminum oxide and its hydrate, aluminum hydroxide, selenium And inorganic aluminum such as aluminum phosphide, aluminum telluride, aluminum phosphate, aluminum phosphide and lithium aluminum aluminate, and organic aluminum such as aluminum benzoate and aluminum citrate. These aluminum-based additives may be added to grease by mixing one type or two types.

  Particularly preferable in the present invention is an aluminum powder having a high extreme pressure effect because it is excellent in heat resistance and hardly decomposes thermally.

  Moreover, the compounding ratio of the aluminum-based additive is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease. That is, (1) When the aluminum-based additive is only aluminum powder, 0.05 to 10 parts by weight of aluminum powder with respect to 100 parts by weight of the base grease, and (2) When the aluminum-based additive is only aluminum compound , 0.05 to 10 parts by weight of the aluminum compound with respect to 100 parts by weight of the base grease, and (3) when the aluminum-based additive is an aluminum powder and an aluminum compound, Combine 0.05 to 10 parts by weight with the aluminum compound.

  If the blending ratio of the aluminum-based additive is less than this blending range, peeling on the raceway surface due to hydrogen embrittlement cannot be effectively prevented. Moreover, even if it exceeds the said range, the peeling prevention effect does not improve any more.

  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, polybutene, GTL oil synthesized by the Fischer-Tropsch method, -Hydrocarbon synthetic oils such as α-olefin oils, alkyl naphthalenes, and alicyclic compounds, or natural oils, polyol ester oils, phosphate ester oils, polymer ester oils, aromatic ester oils, carbonate ester oils, diester oils Non-hydrocarbon synthetic oils such as polyglycol oil, silicone oil, polyphenyl ether oil, alkyldiphenyl ether oil, alkylbenzene oil, and fluorinated oil can be used.

  Among these, it is preferable to use alkyl diphenyl ether oil or poly-α-olefin oil excellent in heat resistance and lubricity.

  Thickeners that can be used in the present invention include benton, silica gel, fluorine compound, lithium soap, lithium complex soap, calcium soap, calcium complex soap, aluminum soap, aluminum complex soap, and other soaps, diurea compounds, polyurea compounds and the like. Examples include urea 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. Diisocyanates include phenylene isocyanate, tolylene diisocyanate, diphenyl isocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, and monoamines include octylamine, dodecylamine, hexadecylamine, stearylamine, 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.

  By adding a thickener such as a urea compound to the base oil, a base grease for blending the aluminum additive and the like 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 is reduced, making it difficult to form a grease. If the content exceeds 40 parts by weight, the obtained base grease becomes too hard and the desired effect is difficult to obtain. Become.

  In addition to the aluminum-based additive, a known grease additive may be included as necessary. Examples of the additives include antioxidants such as organic zinc compounds, amines, and phenolic compounds, metal deactivators such as benzotriazole, clay index improvers such as polymethacrylate and polystyrene, molybdenum disulfide, and graphite. Examples include solid lubricants, metal sulfonates, rust inhibitors such as polyhydric alcohol esters, friction reducers such as organic molybdenum, oil 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.

  In the present invention, in each of the raceway grooves 22 and 24 of the outer ring 23 and the inner ring 25, the curvature radii R1 and R3 of the groove bottom portions 22a and 24a are set to be the same as the radius R of the rolling element 27, and the groove openings 22b and 24b Even when a high moment load is applied by making the curvature radii R2 and R4 larger than the curvature radii R1 and R3 of the groove bottom portions 22a and 24a, the rolling elements (balls) 27 have the outer ring 23 and the shoulder 23a of the inner ring 25, It becomes difficult to ride on 25a, and it is possible to prevent an excessive surface pressure from acting on the rolling contact portion. As a result, the rolling fatigue life of the ball bearing can be ensured while suppressing the inclination of the outer ring 23 with respect to the inner ring 25, and the durability of the bearing can be ensured.

  Moreover, the contact point between the raceway groove 22 of the outer ring 23 and the rolling element 27 is one, the contact point between the raceway groove 24 of the inner ring 25 and the rolling element 27 is one, and the contact point of the rolling element 27 is Two points. In addition, since the groove bottom portions 22a and 24a and the groove opening portions 22b and 24b are smoothly continuous arcs, the rolling of the rolling element 27 becomes smooth. For this reason, it is possible to effectively prevent the occurrence of peeling friction due to heat and sliding, and to reduce the torque.

  By blending the aluminum-based additive, the aluminum compound reacts on the frictional wear surface or the newly formed metal surface exposed by wear, and an aluminum coating is formed on the bearing raceway surfaces (track grooves) 22 and 24 together with iron oxide. The iron oxide and aluminum coatings formed on the raceway surfaces (track grooves) 22 and 24 can suppress the generation of hydrogen due to the decomposition of the grease composition and can prevent peculiar peeling due to hydrogen embrittlement. That is, an aluminum oxide film is formed on the steel surface due to the effect of the aluminum-added grease, and brittle peeling can be prevented by preventing activation of the raceway surface due to metal contact.

  As described above, in the present invention, the brittle peel resistance of a bearing used for electrical accessory use can be improved by a combination of the groove shape and the aluminum-added grease.

  In the above embodiment, the radius of curvature R4 of the groove opening 24b of the raceway groove 24 of the inner ring 25 is set smaller than the radius of curvature R2 of the groove opening 22b of the outer ring 23. The radius of curvature that is advantageous to the bottom of the groove and the radius of curvature that is advantageous to ride on the shoulder are set to the groove opening to create a composite curvature, so when setting the groove radius of curvature of the groove bottom and groove opening, There is no influence.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the radius of curvature R4 of the groove opening 24b of the raceway groove 24 of the inner ring 25 is described. Is larger than the radius of curvature R2 of the groove opening 22b of the outer ring 23, or the radius of curvature R4 of the groove opening 24b of the raceway groove 24 of the inner ring 25 and the radius of curvature R2 of the groove opening 22b of the outer ring 23 are made the same. For example, the radius of curvature of the groove bottom and groove opening can be set to a combination of optimum values for surface pressure and shoulder climbing according to the use conditions.

Examples 1 to 8
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.

After adding the solution in which the monoamine was dissolved while stirring the solution in which the MDI was dissolved,
Stirring was continued at ˜120 ° C. for 30 minutes to produce a diurea compound in the base oil. To this, an aluminum-based additive 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.

In Table 1, the synthetic hydrocarbon used as the base oil is Shinflud 601 manufactured by Nippon Steel Chemical Co., Ltd. with a dynamic clay of 30 mm ² / sec at 40 ° C., and the alkyldiphenyl ether oil is 97 mm ² / sec of dynamic clay at 40 ° C. Moresco High Lube LB100 manufactured by Matsumura Oil Co., Ltd. was used. Moreover, the hindered phenol by Sumitomo Chemical Co., Ltd. was used for antioxidant.

  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 is applied to the pulley attached to the tip of the rotating shaft at 1960 N, the operating speed is set to 0 rpm to 18000 rpm, and the test is performed with a current of 0.1 A flowing in the test bearing. Carried out. 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. As the rolling bearing, a conventional bearing having a groove shape as shown in FIG. 4 was used.

Comparative Examples 1 to 3
In accordance with the method according to Example 1, the base grease was prepared by selecting the thickener and the base oil at the blending ratio shown in Table 1, 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 1. The results are shown in Table 1.

  As shown in Table 1, in each Example, all the rapid acceleration / deceleration tests showed excellent results of 400 hours or more (peeling life time). This is considered to be because the specific exfoliation accompanied by the white texture change that occurs on the rolling surface can be effectively prevented by adding the aluminum-based additive at a predetermined ratio.

It is principal part sectional drawing of the grease enclosure bearing which shows embodiment of this invention. It is principal part sectional drawing of the outer ring | wheel of the said grease enclosure bearing. It is principal part sectional drawing of the inner ring | wheel of the said grease enclosure bearing. It is sectional drawing of the conventional grease enclosure bearing.

Explanation of symbols

22a groove bottom 22b groove opening 22 raceway groove 23 outer ring 24a groove bottom 24b groove opening 24 raceway groove 25 inner ring 26 cage 27 rolling element 28 sealing member

Claims (5)

An outer ring having a raceway groove on the inner peripheral surface, an inner ring having a raceway groove on the outer peripheral surface, a rolling element that freely rolls between the raceway groove of the outer ring and the raceway groove of the inner ring, and a holding that holds the rolling element And a grease-sealed bearing in which a grease composition is enclosed,
In each raceway groove of the outer ring and inner ring, the radius of curvature of the groove bottom is set to be the same as the radius of the rolling element, the radius of curvature of the groove opening is made larger than the radius of curvature of the groove bottom, and the groove bottom and groove opening A grease-enclosed bearing characterized in that a groove opening portion having a large radius of curvature is used as a non-contact portion of a rolling element as a composite groove curvature shape that is combined as a smoothly continuous arc.   The grease composition is formed by adding an additive to a base grease comprising a base oil and a thickener, and the additive contains at least one aluminum-based additive selected from aluminum powder and an aluminum compound. The grease-enclosed bearing according to claim 1, wherein the mixing ratio of the aluminum-based additive is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease.   The grease-sealed bearing according to claim 2, wherein the aluminum compound is at least one compound selected from aluminum carbonate and aluminum nitrate.   The grease-enclosed bearing according to claim 2 or 3, wherein the thickener is a urea-based thickener.   4. The grease-enclosed bearing according to claim 2, wherein the base oil is at least one oil selected from alkyl diphenyl ether oil and poly-α-olefin oil.

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