JP2008069882A - Grease-filled sealing type rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease-filled sealing type rolling bearing, having sealing devices with tight sealing performance and a function of suppressing sliding resistance, and effectively preventing exfoliation of a rolling surface caused by hydrogen brittleness. <P>SOLUTION: In the grease-filled sealing type rolling bearing, the sealing devices 12, 26 are provided, and a grease composition made by blending an additive with base grease made of base oil and thickener is filled. The sealing devices 12, 26 has seal lips 16, 27 made of elastic members. The surface roughness in maximum height Ry or Rmax of a sliding surface of a rotation side member with which the seal lips 16, 27 are brought into slide-contact is 2.0 μm or less, and deflection in a right-angled direction with respect to the sliding surface is regulated to 30 μm or less. The additive of grease compound contains at least one aluminum-based additive selected from aluminum powder and an aluminum compound, and the compounding ratio of the aluminum-based additive is 0.05 to 10 pts.wt. to base grease of 100 pts.wt. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a grease-sealed sealed rolling bearing, and in particular, automotive electrical components such as an alternator, an electromagnetic clutch for a car air conditioner, an intermediate pulley, and an electric fan motor used in an environment where a large amount of foreign matter such as water and muddy water exists. The present invention relates to a grease-sealed sealed type rolling bearing used as a rolling bearing for an auxiliary machine or the like or a rolling bearing for a motor.

  Wheel bearings that support the wheels of automobiles in a freely rotating manner with respect to the suspension system are in an environment where they are directly exposed to rainwater and dust. Sealed type rolling bearings having the characteristics are used. On the other hand, in this type of rolling bearing, since an increase in rotational torque affects the temperature rise and fuel consumption of the bearing, the torque of the bearing is reduced. Since the sliding resistance of the seal is dominant among the torques of the bearing, various sealed rolling bearings having a structure in which the sliding resistance is suppressed while maintaining strong sealing performance have been proposed.

  A typical example of such a wheel bearing will be described with reference to FIG. 1 showing a first embodiment of the present invention. This wheel bearing is a wheel bearing on the drive wheel side, and integrally has a vehicle body mounting flange 2 attached to a vehicle body (not shown) on the outer periphery, and double row outer rolling surfaces 8, 8 on the inner periphery. The outer member 1 formed with a wheel mounting flange 7 to which a wheel (not shown) is attached at one end, and one of the outer members 1 facing the double-row outer rolling surfaces 8 and 8 on the outer periphery. An inner raceway surface 9a, a cylindrical small-diameter step 14 extending in the axial direction from the inner raceway 9a, a hub wheel 4 having a serration 6 for torque transmission formed on the inner periphery, and a small-diameter step 14 and an inner ring 5 on the outer periphery of which the other inner rolling surface 9b is formed.

  A double-row rolling element (ball) 10 is accommodated by a cage 11 between the double-row outer rolling surfaces 8 and 8 and the inner rolling surfaces 9a and 9b facing the outer-rolling surfaces 8 and 8. Sealing devices 12 and 26 are mounted in annular spaces formed between the inner member 3 composed of the hub wheel 4 and the inner ring 5 and the outer member 1, respectively, and lubricating grease sealed inside the bearing. And leakage of rainwater and dust from the outside is prevented.

  Of these sealing devices 12, 26, the sealing device 12 mounted between the outer member 1 and the inner ring 5 is internally fitted to an outer member serving as a fixed-side raceway, as shown in FIG. And a seal ring 17 composed of a core 15 formed in a shape and a seal member 16 integrally vulcanized and bonded to the core 15 and an inner ring 5 serving as a rotation side raceway. And a slinger 18 formed in a shape. The seal member 16 is made of an elastic member such as rubber, and includes three seal lips 23, 24, 25 on the outer side, the middle side, and the inner side, and the tip end edge of the outer seal lip 23 is on the inner side surface of the standing plate portion 22 of the slinger 18. The leading edges of the remaining intermediate seal lip 24 and inner seal lip 25 are brought into sliding contact with the cylindrical portion 21 of the slinger 18.

  On the other hand, the sealing device 26 includes a cored bar 13 that is fitted into the outer member 1 and is formed in an annular shape, and a seal member 27 that is integrally vulcanized and bonded to the cored bar 13. The seal member 27 is made of an elastic member such as rubber, and includes three seal lips 28 a, 28 b, 28 c, and the respective leading edges thereof are in direct sliding contact with the surface of the hub wheel 4.

  In the sealing device 12 on the inboard side among the conventional sealing devices 12 and 26 for wheel bearings, the surface roughness of the slinger 18 that is in sliding contact with the seal lips 23, 24, and 25 is determined by the centerline average roughness (Ra). The maximum height (Ry) is 1.2 μm or less. This makes it difficult for a minute gap to be formed at the maximum height portion, so that it is difficult for foreign matter to enter from the outside and damage to the rolling contact portion due to the alteration of grease is difficult to occur (see Patent Document 1).

  However, in this conventional sealing device 12, the surface roughness of the slinger 18 that is in sliding contact with each of the seal lips 23, 24, 25 is 0.3 μm or less in terms of the center line average roughness (Ra), and the maximum height (Ry In order to limit the thickness to 1.2 μm or less, it is necessary to press the plate material having these target surface roughnesses in advance, or to perform surface processing such as lapping after press processing. Actually, since it is difficult to obtain a plate material having such a target surface roughness, it is necessary to perform surface processing such as lapping after press processing from the viewpoint of cost.

  The lapping process on the surface of such a slinger 18 is extremely difficult to handle and increases the number of processing steps, and has a problem that the shape of the surface is destroyed by the process. Such a shape failure of the sliding surface appears as a change in the seal squeeze, and the followability of the seal lip becomes unstable and the sealability may be lowered.

Further, grease is mainly used for lubrication of these rolling bearings. However, severe use conditions such as high-speed rotation at high temperatures cause a problem in that specific peeling accompanied by a change in white structure occurs at an early stage on the rolling surface of the rolling bearing.
This specific exfoliation is different from the exfoliation from the inside of the rolling contact surface caused by normal metal fatigue, and is considered to be due to hydrogen embrittlement caused by hydrogen due to a fracture phenomenon that occurs from a relatively shallow surface of the rolling surface. Yes. As a method for preventing such a specific peeling phenomenon accompanied by a white tissue change that occurs at an early stage, for example, a method of adding a passivating agent to a grease composition is known (see Patent Document 2). A method of adding bismuth dithiocarbamate to a grease composition is known (see Patent Document 3).
However, in recent years, electrical components and accessories in automobiles, motors in industrial machines, etc., are increasingly used in rolling bearings at high temperatures, such as frequent high-speed operation-sudden deceleration operation-rapid acceleration operation-sudden stop. The method of adding a passivating agent and bismuth dithiocarbamate has become inadequate as a measure for preventing the peeling phenomenon.
JP 2003-184897 A JP-A-3-210394 JP-A-2005-42102

  The present invention has been made in view of such conventional problems, and includes a sealing device having a contradictory function of suppressing sliding resistance while maintaining a strong sealing performance, and rolling due to hydrogen embrittlement. It is an object of the present invention to provide a grease-sealed hermetic rolling bearing that can effectively prevent surface peeling.

The invention according to claim 1 includes an outer member having an outer rolling surface formed on the inner periphery, an inner member having an inner rolling surface opposed to the outer rolling surface on the outer periphery, A rolling element rotatably accommodated between the rolling surfaces; and a seal device mounted in an annular space formed between the outer member and the inner member. In a grease-sealed hermetic rolling bearing in which a grease composition formed by adding an additive to a base grease composed of a lubricant is used, the seal device has a seal lip made of an elastic member, and the seal lip is in sliding contact The surface roughness of the sliding surface of the side member is set to a maximum height Ry or Rmax of 2.0 μm or less, and the runout in the direction perpendicular to the sliding surface is restricted to 30 μm or less. As an additive for aluminum powder Containing at least one aluminum-based additive selected from fine aluminum compound, the mixing ratio of the aluminum-based additive is characterized in that 0.05 to 10 parts by weight relative to the base grease 100 parts by weight.
In particular, the aluminum compound is at least one compound selected from aluminum carbonate and aluminum nitrate. The thickener is a urea-based thickener. Further, the base oil is at least one oil selected from alkyl diphenyl ether oil and poly-α-olefin oil.

Thus, the sealing device has a sealing lip made of an elastic member, and the surface roughness of the sliding surface of the rotating side member that is in sliding contact with the sealing lip is set to a maximum height Ry or Rmax of 2.0 μm or less. In addition, by restricting the deflection in the direction perpendicular to the sliding surface to 30 μm or less, the absolute unevenness of the sliding surface can be suppressed to a small level, and the change of the white balance can be suppressed without increasing the seal size. As in the prior art, it is possible to avoid the problem that the shape of the sliding surface collapses due to slinger lapping or the like. Therefore, the followability of the seal lip with respect to the sliding surface can be stabilized, and the sealing performance is further improved.
Furthermore, at least one aluminum-based additive selected from aluminum powder and aluminum compound blended in the grease composition reacts on the friction wear surface or the new metal surface exposed by wear, and an aluminum coating is formed on the bearing rolling surface. Together with the iron oxide film, generation of hydrogen due to decomposition of the grease composition can be suppressed.

  According to a second aspect of the present invention, the seal device includes a seal ring mounted on the fixed member side and a slinger mounted on the rotating member side, and a seal lip constituting the seal ring is attached to the slinger. As in the past, it is not necessary to strictly control the target surface roughness by applying surface processing such as lapping after pressing, and it is sealed simply by managing the runout of the sliding surface to a predetermined value. Performance can be improved.

  According to a third aspect of the present invention, the seal device includes a seal ring that is mounted on the fixed member side and includes a side lip and a radial lip, and the seal lip can be brought into direct sliding contact with the rotation side member. For example, even when the target surface roughness and runout cannot be obtained, surface processing such as grinding or lapping can be easily performed after the heat treatment.

  According to a fourth aspect of the present invention, the sealing device includes a seal ring that is mounted on the fixed member side and includes a main lip and a sub lip, and the main lip is formed on the rotating side member. If the secondary lip is brought into sliding contact with the flange of the seal groove via a slight shimiro, the secondary lip is maintained along with the wear of the main lip. Can follow and increase the squeezing force, so that the rotational torque of the bearing is suppressed in a state where the amount of wear of the main lip is small, and the squeezing force increases according to the wear of the main lip, thereby ensuring the sealing performance. .

  Preferably, as in the invention described in claim 5, the surface roughness of the sliding surface is set to a maximum height Ry or Rmax of 1.2 μm or less and is perpendicular to the sliding surface. By limiting the runout to 10 μm or less, it is possible to provide a hermetic rolling bearing provided with a sealing device having a contradictory function of suppressing sliding resistance while maintaining and maintaining strong sealing performance. .

  The grease-sealed sealed rolling bearing of the present invention includes an outer member having an outer rolling surface formed on the inner periphery, an inner member having an inner rolling surface facing the outer rolling surface on the outer periphery, In a sealed rolling bearing comprising a rolling element rotatably accommodated between both rolling surfaces, and a sealing device mounted in an annular space formed between the outer member and the inner member, the seal The apparatus has a sealing lip made of an elastic member, and the surface roughness of the sliding surface of the rotating side member in sliding contact with the sealing lip is set to a maximum height Ry or Rmax of 2.0 μm or less, and the sliding By restricting the deflection in the direction perpendicular to the surface to 30 μm or less, the absolute unevenness of the sliding surface can be kept small, and the change can be suppressed without increasing the seal squeezing, As in the past, It can be avoided a problem collapsing the shape of the sliding surface by lapping or the like of gas. Therefore, the followability of the seal lip with respect to the sliding surface can be stabilized, and the sealing performance is further improved.

  In addition, as a grease composition additive, at least one aluminum-based additive selected from aluminum powder and aluminum compound is blended into a base grease consisting of a base oil and a thickener, so that it is used in automobiles and industrial machinery. Occurrence of peculiar peeling due to hydrogen embrittlement seen in the bearing can be suppressed, and the life of the grease-filled bearing can be extended.

  As described above, the grease-sealed sealed rolling bearing of the present invention can effectively prevent specific peeling accompanied by a white structure change occurring on the rolling surface and has excellent bearing life. Therefore, an alternator, an electromagnetic clutch for a car air conditioner, an intermediate pulley It can be suitably used as a rolling bearing for automobile electrical parts such as electric fan motors and auxiliary machines.

Grease-sealed seals that have a contradictory function of suppressing sliding resistance while maintaining strong sealability, and that can effectively prevent peeling on the rolling surface due to hydrogen embrittlement in grease-filled bearings The diligent examination was done about the type rolling bearing. As a result, the sealing device used for the rolling bearing has a sealing lip made of an elastic member, and the surface roughness of the sliding surface of the rotating side member in sliding contact with the sealing lip is set to the maximum height Ry or Rmax. A grease composition containing 1.2 μm or less, with the deflection in the direction perpendicular to the sliding surface restricted to 10 μm or less, and further containing at least one aluminum-based additive selected from aluminum powder and aluminum compounds A rapid acceleration / deceleration test was conducted using the enclosed rolling bearing, and it was found that the bearing life could be extended.
The surface analysis of the bearing rolling surface shows that the aluminum compound reacts with the frictional wear surface or the new metal surface exposed by wear by forming an aluminum additive, and an aluminum coating is formed on the bearing rolling surface along with iron oxide. I understood the result. The iron oxide and aluminum coating produced on the bearing rolling surface can suppress the generation of hydrogen due to the decomposition of the grease composition.
As described above, according to the present invention, the effect of contributing to the lubrication of the bearing ring without leaking the enclosed grease by the action of the improvement of the sealing performance and the production of the aluminum coating on the bearing rolling surface, and the rolling Rather than individually pulling out the effect of preventing specific exfoliation with white tissue changes that occur on the running surface, it is possible to perform specific exfoliation with white tissue changes that occur on the rolling surface by overlapping each action. It is considered that the effect to prevent can be exhibited synergistically and the bearing life is dramatically improved. The present invention is based on these findings.

The aluminum-based additive added to the grease composition used in the present invention is at least one selected from aluminum powder and 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 Aluminum fluoride, aluminum telluride, aluminum phosphate, aluminum phosphide, lithium aluminate, magnesium aluminate, aluminum selenate, aluminum titanate, aluminum zirconate and other inorganic aluminum, aluminum benzoate, aluminum citrate and other organic aluminum Is mentioned. 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.

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. That is, (1) when the aluminum 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 additive is only aluminum compound, 0.05 to 10 parts by weight of aluminum compound per 100 parts by weight of grease, and (3) when aluminum additive is aluminum powder and aluminum compound, aluminum powder and aluminum compound are added to 100 parts by weight of base grease. Combine 0.05 to 10 parts by weight.
If the blending ratio of the aluminum-based additive is less than 0.05 parts by weight, peeling on the rolling surface due to hydrogen embrittlement cannot be effectively prevented. Moreover, even if the amount exceeds 10 parts by weight, the anti-peeling effect does not improve further.

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 oil such as α-olefin oil, alkylnaphthalene, alicyclic compound, etc., or natural oil, polyol ester oil, phosphate ester oil, polymer ester oil, aromatic ester oil, carbonate ester oil, diester oil 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 compounds, lithium soap, lithium complex soap, strong lucium soap, calcium complex soap, aluminum soap, aluminum complex soap, and other soaps, diurea compounds, polyurea compounds, etc. These urea compounds are mentioned.
Of these, urea compounds are desirable in view of heat resistance, cost, and the like.

A urea compound is obtained by reacting an isocyanate compound and an amine compound. In order not to leave a reactive free radical, the isocyanate group of the isocyanate compound and the amino group of the amine compound are preferably blended so as to be approximately equivalent.
A diurea compound is obtained by reaction of a diisocyanate and a monoamine, for example. Examples of the diisocyanate include phenylene diisocyanate, tolylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, etc., and monoamines include octylamine, dodecylamine, hexadecylamine, stearylamine, Examples include oleylamine, aniline, p-toluidine, cyclohexylamine and the like. The polyurea compound can be obtained, for example, by reacting diisocyanate with a monoamine or diamine. Examples of the diisocyanate and monoamine include those similar to those used for the production of the diurea compound. Examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, And diaminodiphenylmethane.

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 will be reduced, making it difficult to make grease, and if it exceeds 40 parts by weight, the resulting base grease will be too hard and the desired effect will not be obtained. Become.

  In addition to the 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, viscosity 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.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a first embodiment of a grease-sealed sealed rolling bearing according to the present invention. This sealed-type rolling bearing is applied to a wheel bearing that rotatably supports a driving wheel of an automobile with respect to a suspension device. The basic configuration of the wheel bearing has been described with reference to FIG. 1 as an example of a sealed rolling bearing provided with the above-described sealing device. Therefore, detailed description is omitted, and the characteristic portion of the present invention is mainly used. explain.

  In this sealed rolling bearing, a sealing device is provided in an annular space formed by a hub ring 4 and an inner ring 5 and formed between an inner member 3 serving as a rotation side member and an outer member 1 serving as a fixed side member. 12 and 26 are mounted to prevent leakage of grease containing the aluminum-based additive encapsulated inside the bearing and intrusion of rainwater or dust from the outside into the bearing.

  Of these sealing devices 12, 26, the sealing device 12 on the inboard side (right side in the figure) mounted between the outer member 1 and the inner ring 5 is fitted into the outer member 1 as shown in FIG. , A metal ring 15 formed in a L-shaped cross section, a seal ring 17 composed of a sealing member 16 integrally vulcanized and bonded to the metal core 15, and an outer ring fitted to the inner ring 5. And a formed slinger 18. The slinger 18 and the core metal 15 of the seal ring 17 are formed by pressing an austenitic stainless steel plate (JIS standard SUS304 or the like) or a rust-proof cold rolled steel plate (JIS standard SPCC or the like). It is formed by.

  The seal member 16 is made of an elastic member such as rubber, and includes three seal lips 23, 24, 25 on the outer side, the middle side, and the inner side, and the tip end edge of the outer seal lip 23 is on the inner side surface of the standing plate portion 22 of the slinger 18. The leading edges of the remaining intermediate seal lip 24 and inner seal lip 25 are brought into sliding contact with the cylindrical portion 21 of the slinger 18. Here, the surface roughness of the slinger 18 that is in sliding contact with each of the seal lips 23, 24, and 25 is set to a maximum height Ry or Rmax of 2.0 μm or less, preferably 1.2 μm or less, and with respect to the sliding surface. Therefore, the deflection in the perpendicular direction is restricted to 30 μm or less, preferably 10 μm or less. That is, it is not necessary to strictly control the target surface roughness by simply controlling the runout of the sliding surface and applying surface processing such as lapping after press processing as in the prior art.

  As a result, the absolute unevenness of the sliding surface can be suppressed to a certain extent, and the change of the squeezing can be suppressed without increasing the squeezing of the seal. The problem that the shape of the sliding surface collapses can also be avoided. Therefore, the followability of the seal lips 23, 24, 25 with respect to the sliding surface can be stabilized, and the sealing performance is further improved.

  On the other hand, as shown in FIG. 3, the sealing device 26 is fitted into the outer member 1, each of which is formed in an annular shape, and a sealing member 27 that is integrally vulcanized and bonded to the cored bar 13. It consists of. The core 13 is formed by pressing an austenitic stainless steel plate (JIS standard SUS304 type or the like) or a rust-proof cold rolled steel plate (JIS standard SPCC type or the like). The seal member 27 is made of an elastic member such as rubber, and includes two side lips (dust seals) 28a and 28b and a single radial lip (grease seal) 28c. The wheel mounting flange 7 is in direct sliding contact with the arcuate sliding surface 19 formed on the inboard side base of the wheel mounting flange 7.

  Here, the surface roughness of the sliding surface 19 that is in sliding contact with each of the seal lips 28a, 28b, and 28c is set to a maximum height Ry or Rmax of 2.0 μm or less, preferably 1.2 μm or less. 19 is controlled to be 30 μm or less, preferably 10 μm or less. When such target surface roughness and runout cannot be obtained, surface processing such as grinding or lapping may be performed after the heat treatment.

  As a result, like the sealing device 12 described above, the absolute unevenness of the sliding surface 19 can be suppressed to a certain extent, and the change of the squeezing can be suppressed without increasing the squeezing of the seal. Therefore, the followability of the seal lips 28a, 28b, 28c with respect to the sliding surface 19 can be stabilized, and the sealing performance is further improved.

  FIG. 4 is a longitudinal sectional view showing a second embodiment of the grease-sealed sealed rolling bearing of the present invention, and FIG. 5 is an enlarged view of a main part of FIG. The sealed rolling bearing 20 is a deep groove ball bearing, and includes an outer ring 30 having an outer rolling surface 29 formed on the inner periphery, an inner ring 32 having an inner rolling surface 31 formed on the outer periphery, both rolling surfaces 29, A pair of seal rings 35, 35 are mounted in an annular space formed between a ball 34 accommodated in a freely rolling manner by a cage 33 between 31 and inner and outer rings 32, 30. The pair of seal rings 35 and 35 prevent leakage of grease containing the aluminum-based additive enclosed in the bearing, and intrusion of rainwater, dust, and the like from the outside into the bearing.

  As shown in FIG. 5, the seal ring 35 includes a disk-shaped metal core 36 formed by press-working a cold-rolled steel plate (JIS standard SPCC system, etc.), and the core metal 36 integrally. It is composed of a seal member 37 that is sulfur bonded. The seal member 37 has a main lip 37a formed by bifurcating the tip and a sub lip 37b. The seal ring 35 is fitted to the inner periphery of the end of the outer ring 30 via the seal member 37, and the seal member 37 is formed in a seal groove 38 having a substantially U-shaped cross section formed on the outer periphery of the end of the inner ring 32. Direct sliding contact. Specifically, the main lip 37a is in sliding contact with the inclined sliding surface 39 of the seal groove 38, and the sub lip 37b is in sliding contact with the small-diameter portion (sealed portion of the seal groove) 40 through a slight shimoshiro. Yes. Since the base portion of the sub lip 37b is constricted, the waist is weak, and as the main lip 37a wears, the left side in the figure is followed to increase the squeeze with the small diameter portion 40. Therefore, in a state where the amount of wear of the main lip 37a is small, the rotational torque of the bearing is suppressed, and the squeeze increases according to the wear of the main lip 37a, thereby ensuring the sealing performance.

  Here, the surface roughness of at least the sliding surface 39 in sliding contact with the main lip 37a in the seal groove 38 is 2.0 μm or less, preferably 1.2 μm or less in terms of the maximum height Ry or Rmax. The deflection in the direction perpendicular to the surface 39 is restricted to 30 μm or less, preferably 10 μm or less. In addition, when such target surface roughness and runout cannot be obtained, surface processing such as shot peening or lapping may be performed after the heat treatment.

  Thereby, the absolute unevenness of the sliding surface 39 can be suppressed to a certain extent, and the change of the squeezing can be suppressed without increasing the squeezing of the seal. Therefore, the followability of the main lip 37a with respect to the sliding surface 39 can be stabilized, and the sealing performance is further improved.

Reference Example 1 to Reference Example 2 and Reference Comparative Example 1
FIG. 6 is a graph showing the results of a muddy water test on a single bearing carried out by the present applicant.
In this test, a Kanto Loam JIS 8 type mixed solution was sprayed to measure the mass change before and after the test. As can be clearly seen from this figure, the test sample has a maximum height Ry or Rmax of 2.02 to 3.7 μm and a runout in a direction perpendicular to the sliding surface 39 of more than 30 μm (reference comparison) Example 1), specimen with maximum height Ry or Rmax of 1.3 to 1.86 μm and runout in the direction perpendicular to sliding surface 39 of 10 to 30 μm (Reference Example 1), and maximum height It was verified that there was a significant difference between the test sample (Reference Example 2) in which Ry or Rmax was 0.7 to 1.2 μm and the runout in the direction perpendicular to the sliding surface 39 was 10 μm or less.

Examples 1 to 6
In half of the base oil shown in Table 1, 4,4-diphenylmethane diisocyanate (trade name Millionate MT manufactured by Nippon Polyurethane Industry Co., Ltd., hereinafter referred to as MDI) is dissolved in the proportion shown in Table 1, and the remaining half In this base oil, a monoamine that was twice the equivalent of MDI was dissolved. The respective blending ratios and types are shown in Table 1.
A solution in which monoamine was dissolved was added while stirring the solution in which MDI was dissolved, and then the reaction was continued for 30 minutes at 100 ° C. to 120 ° C. to produce a diurea compound in the base oil.
To this, an aluminum-based additive and an antioxidant were added in the proportions shown in Table 1, and the mixture was further stirred at 100 to 120 ° C. for 10 minutes. Thereafter, the mixture was cooled and homogenized with three rolls to obtain a grease composition.

In Table 1, the kinematic viscosity 30 mm ² / sec of Nippon Steel Chemical Co., trade name of Shin fluid 601 in the synthetic hydrocarbon oil is 40 ° C. was used as the base oil, kinematic viscosity alkyl ether oil at 40 ℃ 97 mm ² / Moresco HighLube LB100, a trade name of Matsumura Oil Co., sec. Moreover, the hindered phenol by Sumitomo Chemical Co., Ltd. was used for antioxidant.
The obtained grease composition is encapsulated in a rolling bearing in which the surface roughness of the sliding surface of the rotating side member in sliding contact with the seal lip and the vibration in the direction perpendicular to the sliding surface are regulated as shown in Table 1. An acceleration / deceleration test was conducted. 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, the grease composition was sealed in a rolling bearing, and a rapid acceleration / deceleration test was performed. The rapid acceleration / deceleration test conditions are as follows: the load applied to the pulley attached to the tip of the rotating shaft is set to 1960 N, the operating speed is set to 0 rpm to 18000 rpm, and a current of 0.1 A flows through the test bearing. The test was conducted. Then, abnormal peeling occurred in the bearing, and the time when the vibration of the vibration detector exceeded the set value and the generator stopped (peeling life time, h) was measured. The test was terminated after 500 hours.

Comparative Examples 1 to 3
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. A rolling bearing in which the surface roughness of the sliding surface of the rotating side member in sliding contact with the seal lip and the vibration in the direction perpendicular to the sliding surface is regulated as shown in Table 1 is filled with the obtained grease composition. The same test as in No. 1 was performed and evaluated. The results are shown in Table 1.

  The grease-sealed hermetic rolling bearing of the present invention can effectively prevent specific delamination accompanied with white structure change occurring on the rolling surface, can stabilize the followability of the seal lip to the sliding surface, and has a sealing performance. Since the bearing life is further improved and the bearing life is excellent, it can be suitably used as an alternator, a car air conditioner electromagnetic clutch, an intermediate pulley, an automobile electrical component such as an electric fan motor, a rolling bearing of an auxiliary machine, and a motor bearing.

It is a longitudinal cross-sectional view which shows 1st Embodiment of the grease sealing sealing type rolling bearing of this invention. It is a principal part expanded sectional view which shows the sealing apparatus of an inboard side same as the above. It is a principal part expanded sectional view which shows the sealing apparatus by the side of an outboard same as the above. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the grease sealing sealing type rolling bearing of this invention. It is a principal part expanded sectional view same as the above. It is a graph which shows the result of the muddy water test in the bearing simple substance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer member 2 Car body mounting flange 3 Inner member 4 Hub wheel 5, 32 Inner ring 6 Serration 7 Wheel mounting flange 8, 29 Outer rolling surface 9a, 9b, 31 Inner rolling surface 10 Rolling body 11, 33 Cage 12 , 26 Sealing device 13, 15, 36 Core metal 14 Small-diameter step portion 16, 27, 37 Seal member 17, 35 Seal ring 18 Slinger 19, 39 Sliding surface 20 Sealed rolling bearing 21 Cylindrical portion 22 Standing plate portion 23 Outer seal Lip 24 Intermediate seal lip 25 Inner seal lip 28a, 28b Side lip 28c Radial lip 30 Outer ring 34 Ball 37a Main lip 37b Sub lip 38 Seal groove 40 Small diameter part

Claims (8)

An outer member having an outer rolling surface formed on the inner periphery, an inner member having an inner rolling surface facing the outer rolling surface on the outer periphery, and rotatably accommodated between both the rolling surfaces. And a sealing device mounted in an annular space formed between the outer member and the inner member, and added to the base grease comprising a base oil and a thickener in the annular space. In a grease-sealed hermetic rolling bearing in which a grease composition containing an agent is enclosed,
The sealing device has a sealing lip made of an elastic member, and the surface roughness of the sliding surface of the rotating side member in sliding contact with the sealing lip is set to a maximum height Ry or Rmax of 2.0 μm or less, and The runout in the direction perpendicular to the sliding surface is restricted to 30 μm or less,
As an additive of the grease composition, it contains at least one aluminum-based additive selected from aluminum powder and aluminum compound, and the mixing ratio of the aluminum-based additive is 0.05 to 10 weights with respect to 100 parts by weight of the base grease. Grease-sealed sealed type rolling bearing characterized by being a part.   2. The grease according to claim 1, wherein the seal device includes a seal ring mounted on the fixed member side and a slinger mounted on the rotating member side, and a seal lip constituting the seal ring is in sliding contact with the slinger. Encapsulated rolling bearing.   The grease-sealed hermetic rolling bearing according to claim 1, wherein the seal device includes a seal ring having a side lip and a radial lip that is mounted on the fixed member side, and the seal lip is in direct sliding contact with the rotating side member.   The seal device is mounted on the fixed member side and includes a seal ring having a main lip and a sub lip, and the main lip is slid directly into a seal groove having a substantially U-shaped cross section formed on the rotation side member, 2. The grease-sealed sealed rolling bearing according to claim 1, wherein the sub lip is slidably contacted with a flange portion of the seal groove via a slight squeeze.   5. The surface roughness of the sliding surface is set to a maximum height Ry or Rmax of 1.2 μm or less, and runout in a direction perpendicular to the sliding surface is restricted to 10 μm or less. A sealed grease type rolling bearing according to any one of the preceding claims.   The grease-sealed sealed rolling bearing according to any one of claims 1 to 5, wherein the aluminum compound is at least one compound selected from aluminum carbonate and aluminum nitrate.   The grease-enclosed sealed rolling bearing according to any one of claims 1 to 6, wherein the thickener is a urea-based thickener.   The grease-sealed hermetic rolling bearing according to any one of claims 1 to 7, wherein the base oil is at least one oil selected from alkyl diphenyl ether oil and poly-α-olefin oil. .

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