JP4877343B2 - Rolling bearing - Google Patents

Description

  The present invention relates to a rolling bearing in which a grease composition is enclosed, and in particular, under high temperature, high speed, high load and high vibration conditions such as automobile electrical components, engine auxiliary machines such as alternators and intermediate pulleys, and electromagnetic clutches for car air conditioners. The present invention relates to a rolling bearing that is suitable for use in the present invention and has good rust prevention performance and excellent peeling life.

  Rolling bearings are generally used for rotating parts of various power systems of automobile engines, such as alternators, car air conditioner electromagnetic clutches, automotive electrical parts such as intermediate pulleys, and engine accessories, and grease is mainly used for lubrication. Has been.

  Due to the spread of FF vehicles for the purpose of reducing the size and weight of automobiles, and the demand for expansion of migration spaces, the volume of the engine room has been reduced, and the above-mentioned electrical components and engine accessories have been reduced in size and weight. More progress is being made. In addition, there is an increasing demand for higher performance and higher output for each component. However, the reduction in output is unavoidable due to the miniaturization, for example, the alternator and the electromagnetic clutch for car air conditioner compensate for the decrease in output by increasing the speed, and the idler pulley is also increased in speed accordingly. become. Furthermore, since the engine room is being sealed due to a demand for improvement in quietness and the high temperature in the engine room is promoted, each of the components must also withstand high temperatures. With such high speed and high performance, peeling of the respective component bearings accompanied by a change in white structure due to hydrogen embrittlement is likely to occur, and prevention thereof is a new important issue.

  In addition, since the above parts are often attached to the lower part of the engine room, they are likely to be exposed to rain water during running, and the grease sealed in the rolling bearings for these parts is used elsewhere. Rust prevention performance is required to be better than grease sealed in rolling bearings.

  In order to impart antirust performance to grease, it is common to add an antirust additive. An inorganic passivating agent is often included as a component of the rust preventive additive, but sodium nitrite is the most effective and mainstream among others. In addition, since this inorganic passivating agent is water-soluble and difficult to disperse in oil-based ones such as grease, greases that are used in combination with surfactants are also commercially available. In addition, a grease in which an oil-soluble organic inhibitor, a water-soluble inorganic passivating agent (sodium nitrite, etc.) and a rust preventive agent composed of a nonionic surfactant are added to the grease is proposed (for example, Patent Document 1). reference). However, sodium nitrite, which is a typical inorganic passivating agent, has excellent rust-preventing performance, but may induce carcinogenicity depending on the conditions of use, and there is no legal restriction, but its use is not recommended. It is better to avoid it. In addition, sulfonic acid metal salts, which are organic inhibitors, are widely used because of their high rust prevention ability. However, as described in Japanese Patent Publication No. 2878749, hydrogen brittle exfoliation occurs in order to promote the generation of hydrogen. It can be a cause.

Japanese Patent Application Laid-Open No. 3-200958

  The present invention has been made in view of the above circumstances, and is particularly suitable for use under high temperature, high speed, high load and high vibration conditions, has no harm to the human body, and has good rust prevention performance and excellent peeling. An object is to provide a rolling bearing having a long life.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that zinc naphthenate and succinic acid derivatives are effective as anticorrosive additives, and have completed the present invention.

That is, the above object is that the synthetic oil of the present invention is a base oil, a diurea compound is a thickener, and zinc naphthenate and alkenyl succinic acid half ester total 0.25 to 5% by mass of the total amount of grease. The present invention achieves a rolling bearing characterized in that the added grease composition having an anti-separation effect is enclosed in a bearing space formed by an inner ring, an outer ring and rolling elements.

  According to the present invention, a rolling bearing having no harm to the human body, good rust prevention, and extremely excellent anti-peeling effect can be obtained, particularly an alternator, an electromagnetic clutch for a car air conditioner, an intermediate pulley, an electric fan motor, Rolling bearings suitable for automobile electrical parts such as water pumps, engine accessories, and the like are provided.

In an Example, it is the graph which calculated | required the relationship between the addition amount of a rust preventive additive, a rust evaluation score, and peeling incidence about grease A, grease B, and grease E. In an Example, it is the graph which calculated | required the relationship between the addition amount of a rust preventive additive, the rust evaluation score, and the peeling occurrence rate about grease C and grease D.

  Hereinafter, the rolling bearing of the present invention will be described in detail. In the present invention, the structure of the bearing itself is not limited, and various known ball bearings, roller bearings, and the like can be targeted. A bearing space formed by the inner ring, the outer ring, and the rolling element is described later. The rolling bearing of the present invention is constituted by enclosing a grease composition containing a rust preventive additive.

[Base oil]
In the present invention, synthetic oil is used as the base oil of the grease composition. Further, the base oil has a kinematic viscosity at 40 ° C. of preferably 10 to 400 (in order to avoid generation of abnormal noise at low temperature startup due to insufficient low temperature fluidity and seizure that occurs because an oil film is hardly formed at high temperature. mm ² / sec), more preferably 20 to 250 (mm ² / sec), and still more preferably 40 to 150 (mm ² / sec).

  Specific examples of synthetic oils include hydrocarbon oils, aromatic oils, ester oils, ether oils, and the like. Examples of the hydrocarbon oil include poly-α-olefins such as normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, 1-decene and ethylene co-oligomer, and hydrides thereof. Examples of the aromatic oil include alkylbenzenes such as monoalkylbenzene and dialkylbenzene, and alkylnaphthalenes such as monoalkylnaphthalene, dialkylnaphthalene and polyalkylnaphthalene. Examples of the ester oil include diester oil such as dibutyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, ditridecyl glutarate, and methyl acetyl cinnolate, or trioctyl triphosphate. Aromatic ester oils such as melitrate, tridecyl trimellitate, tetraoctyl pyromellitate, and more, for example, trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol belargo Polyol ester oils such as nates, and also complex ester oils that are oligoesters of polyhydric alcohols and mixed fatty acids of dibasic acids and monobasic acids. . Examples of the ether oil include polyglycols such as polyethylene glycol, polypropylene glycol, polyethylene glycol monoether, and polypropylene glycol monoether, or monoalkyl triphenyl ether, alkyl diphenyl ether, dialkyl diphenyl ether, pentaphenyl ether, tetraphenyl ether, And phenyl ether oils such as monoalkyl tetraphenyl ether and dialkyl tetraphenyl ether. Examples of other synthetic lubricating base oils include tricresyl phosphate, silicone oil, perfluoroalkyl ether, and the like.

  Among the above base oils, poly-α-olefin, dibutyl sebacate, diisodecyl adipate, pentaerythritol-2-ethylhexanoate, dialkyl diphenyl ether, and the like are particularly preferable. These base oils can be used alone or as a mixture, and are adjusted to the above-mentioned preferable kinematic viscosity.

[Thickener]
For the thickener, a diurea compound is used in consideration of heat resistance and acoustic properties of the grease.

[Additive]
Additives include zinc naphthenate and alkenyl succinic acid half ester . These zinc naphthenates and alkenyl succinic acid half esters are safe compounds that do not affect the human body.

(concentration)
Added pressure of the zinc naphthenate and alkenyl succinic acid half ester is 0.25 to 5 mass% in total with respect to grease the total amount. If the amount added is less than this, sufficient rust prevention properties cannot be obtained, and if it is added more than this, the grease will soften and grease leakage may occur, such being undesirable. To ensure corrosion resistance, if considering the seizure life by grease leakage, have to desired to 0.5 to 5 mass% in total with respect to grease the total amount.

  Various conventionally known additives such as an extreme pressure agent and an oily agent may be added to the grease composition as necessary.

[Production method]
The method for preparing the grease composition is not particularly limited, but it is preferable to add a predetermined amount of zinc naphthenate and succinic acid derivative to the grease composition obtained by reacting the thickener in the base oil. At that time, it is necessary to add zinc naphthenate and a succinic acid derivative with a kneader, a roll mill or the like and then sufficiently stir and disperse uniformly. When this treatment is performed, heating is also effective. Moreover, when adding additives other than zinc naphthenate and a succinic acid derivative, adding simultaneously with zinc naphthenate and a succinic acid derivative is preferable on a process.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Preparation of grease)
As shown in Table 1, greases C to E were prepared. The preparation method involves reacting a base oil mixed with diisocyanate and the same base oil mixed with amine, and stirring and heating to a semi-solid product obtained by pre-dissolving in the same base oil An agent was added and sufficiently stirred. After slow cooling, zinc naphthenate, alkenyl succinic acid half ester and Ba sulfonate were added as appropriate, and a grease was obtained by passing through a roll mill. Also, for each grease, the amount of zinc naphthenate, alkenyl succinic acid half ester or Ba sulfonate is 0.05%, 0.1%, 0.5%, 1% and 5% by weight of the total amount of grease. 5 types were prepared.

(Rapid acceleration / deceleration test)
The peel life was evaluated by rapidly accelerating and decelerating a bearing incorporated in an alternator using an engine. That is, a single row deep groove ball bearing (inner diameter φ17 mm, outer diameter φ47 mm, width 14 mm) encapsulating 2.36 g of each of the above greases is incorporated in an alternator, and the engine speed is 1000 to 6000 rpm (bearing speed 2400 to 13300 rpm), The bearing was continuously rotated under the condition of a pulley load of 1764N in a room temperature atmosphere, and the test was conducted with a target of 500 hours. Moreover, the test was finished when the bearing outer ring raceway was separated and vibrations occurred. The test was performed 10 times for each condition, and evaluated by the peeling occurrence rate defined below, and the results were plotted in FIG. 1 and FIG.
Peeling occurrence rate (%) = (number of peeling occurrence / number of tests) × 100

(Rust prevention test)
2.3 g of each grease described above was sealed in a deep groove ball bearing with an inner diameter φ17 mm, an outer diameter φ47 mm, and a width 14 mm with a circular contact rubber seal, and rotated at 1800 rpm for 1 minute. After the rotation, 0.5 ml of 0.5 mass% salt water was poured into the bearing and rotated at 1800 rpm for 1 minute. After being left for 120 hours under conditions of 60 ° C. and 100% RH, the state of rust generation on the inner and outer raceways of the test bearing was observed. Although the evaluation criteria are shown in Table 2, the case where the rust occurrence state was 2 or less was regarded as acceptable. The test was performed 10 times for each condition, and the results were plotted in FIG. 1 and FIG.

As shown in FIGS. 1 and 2, by zinc naphthenate and alkenyl succinic acid half ester as an anti-rust additive in accordance with the present invention to encapsulate including grease C and greases D, and generation of the bearings of rust and peeling Can be suppressed . The Ba sulfonate is a conventional anti-rust additives against this, although rust is not observed, delamination occurs.

That is, in FIG. 2 , the rust evaluation score of 2 or less is satisfied at the leftmost point (addition amount of rust preventive additive is 0.15% by mass). This indicates that good results can be obtained if the total amount of rust preventive additives is at least 0.15% by mass at the lower limit, but the rust evaluation point is 0.1% by mass. Therefore, it is shown that the preferable lower limit of the addition amount is 0.25% by mass exceeding 0.15% by mass, and more preferably 0.5% by mass. .

In FIGS. 1 and 2, for convenience of illustration, each point of the grease C and greases D, and are shown by shifting the line connecting them, in fact each point and line are overlapped.

Claims (3)

The synthetic oil as a base oil, a thickener a diurea compound, a grease composition having the added anti-stripping effect such that 0.25 to 5 wt% of the grease total amount of zinc naphthenate and alkenyl succinic acid half ester in total A rolling bearing characterized in that an object is enclosed in a bearing space formed by an inner ring, an outer ring and rolling elements. 2. The rolling bearing according to claim 1, wherein the total amount of zinc naphthenate and alkenyl succinic acid half ester added to the grease composition is 0.5 to 5% by mass of the total amount of grease. The rolling bearing according to claim 1 or 22, wherein the base oil is an ether oil or a poly α-olefin .

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