JP2007077350A - Roller bearing for electromagnetic clutch, compressor and idler pulley - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roller bearing which is used for an electromagnetic clutch, compressor or idler pulley, is excellent in anti-seizing life and rust preventability, prevents the occurrence of white texture release, and has excellent durability. <P>SOLUTION: This roller bearing which is used for the electromagnetic clutch, compressor or idler pulley and in which grease is sealed is characterized in that the grease comprises an ester oil having dynamic viscosity of 20 to 100 mm<SP>2</SP>/s at 40°C and a pour point of ≤-40°C as a base oil and a diurea compound in an amount of 10 to 30 mass% based on the total amount of the grease as a thickening agent, contains at least two of a carboxylic acid-based rust-preventing agent, a carboxylate-based rust-preventing agent, an ester-based rust-preventing agent, and an amine-based rust-preventing agent in a total amount of 1 to 10 mass% based on the total amount of the grease and in a single amount of 0.5 to 9.5 mass%, and an organic molybdenum compound in an amount of 1 to 5 mass% based on the total amount of the grease. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rolling bearing used for parts used under high-temperature, high-speed, high-load conditions such as automotive electrical components, electromagnetic clutches for car air conditioners as engine accessories, compressors, and idler pulleys.

  Due to demands for smaller and lighter automobiles and further expansion of living space, the engine room space has been inevitably reduced, and electrical components and engine accessories have been further reduced in size and weight. Electromagnetic clutches and compressors for car air conditioners The idler pulley is no exception. However, a reduction in output is unavoidable due to downsizing, and the electromagnetic clutch compensates for the reduction in output by increasing the speed, and accordingly, the idler pulley is also increased in speed. 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, these parts are also required to withstand high temperatures. In addition, since these parts are often attached to the lower part of the engine room, they are likely to be exposed to rainwater and muddy water during traveling, and the grease used for the rolling bearings for these parts has other locations. Therefore, it is necessary to use a grease with better rust prevention performance than the grease used in

  At present, urea-synthetic oil grease containing synthetic oil as a base oil and urea compound as a thickener is mainly used in rolling bearings for electromagnetic clutches, rolling bearings for compressors, and rolling bearings for idler pulleys. Up to a temperature of 170 to 180 ° C., the bearing lubrication life is long and can be used sufficiently.

  Recently, however, there have been an increasing number of products that are made lighter by changing the pulley material of the electromagnetic clutch, compressor, and idler pulley from metal to resin. Resins have poorer heat dissipation than metals, so the bearings become increasingly hot and sometimes exceed 180 ° C. When the urea-synthetic oil grease is used at a temperature of 180 ° C. or higher, the base oil evaporates intensely, the grease hardens, and sometimes the thickener is destroyed and softened, resulting in early seizure.

  From such a background, it has been practiced to improve heat resistance by enclosing fluorine-based grease in a rolling bearing (for example, see Patent Documents 1 and 2). However, this rolling bearing can be used in a high temperature range of 200 ° C., and is effective only under a low load. Under a high load, heat generation increases and seizure occurs early. In addition, rust preventives are generally added to improve rust prevention performance, but rust preventives that can be added to fluorine-based grease are limited, and are inferior in rust prevention compared to urea-synthetic oil-based greases. There are also disadvantages of being expensive and expensive.

  Further, in the rolling bearing used in each of the above parts, hydrogen is generated by moisture in the bearing, and this hydrogen penetrates into the bearing steel constituting the inner ring, the outer ring, and the rolling element to form a white structure due to hydrogen embrittlement. There is a case of causing the accompanying peeling, and it is also important to suppress the occurrence of the white tissue peeling.

JP 2000-273478 A JP 2000-303088 A

  The present invention has been made in view of the circumstances as described above, and has excellent seizure life and rust prevention properties, and further suppresses the occurrence of white tissue peeling, and is excellent in durability for electromagnetic clutches, compressors, and idlers. An object is to provide a rolling bearing for a pulley.

In order to achieve the above object, the present invention provides the following rolling bearings for electromagnetic clutches, compressors and idler pulleys.
(1) In rolling bearings for electromagnetic clutches, compressors and idler pulleys, in which a plurality of rolling elements are rotatably held between an inner ring and an outer ring, and grease is sealed.
The grease has an ester oil having a kinematic viscosity at 40 ° C. of ²⁰ to 100 mm ² / s and a pour point of −40 ° C. or less as a base oil, and a diurea compound as a thickener is 10 to 30% by mass of the total amount of the grease. 1 to 10% by mass of the total amount of grease, and at least two types of carboxylic acid-based rust preventive, carboxylate-based rust preventive, ester-based rust preventive and amine-based rust preventive Rolling bearings for electromagnetic clutches, compressors and idler pulleys, each containing 0.5 to 9.5% by mass and an organomolybdenum compound in a proportion of 1 to 5% by mass of the total amount of grease.
(2) The one-way clutch built-in rotation transmission device according to (1), wherein the diurea compound is a diurea compound represented by the following general formula (I).
R1-NHCONH-R3-NHCONH-R2 (I)
(In the formula, R1 and R2 are hydrocarbon groups having 6 to 18 carbon atoms, which may be the same or different, and R3 is an aromatic hydrocarbon group having 6 to 15 carbon atoms.)

  The rolling bearings for electromagnetic clutches, compressors and idler pulleys according to the present invention use ester oil having a specific kinematic viscosity and pour point as the base oil in the encapsulated grease, and use a diurea compound having excellent heat resistance as a thickener. Therefore, it exhibits good lubricity from low temperature to high temperature, and by adding a specific rust preventive agent, more excellent rust prevention performance is imparted, and a certain extreme pressure agent imparts excellent peel resistance. It will be excellent in durability.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  In the present invention, the structure itself of the rolling bearing for the electromagnetic clutch, the compressor, and the idler pulley is not limited. For example, a ball bearing as shown in FIG. 1 can be exemplified. The illustrated ball bearing 21 includes an outer ring 22, an inner ring 23, a plurality of balls 24 that are rotatably disposed between the outer ring 22 and the inner ring 23, and a cage 25 that holds the plurality of balls 24. , And non-contact type seals 26, 26 attached to the seal groove 22b of the outer ring 22. A space surrounded by the outer ring 22, the inner ring 23, and the seals 26 and 26 is filled with grease 27 described later, and is sealed inside the ball bearing 21 by the seal 26.

As the base oil of the grease, an ester oil having a kinematic viscosity at 40 ° C. of ²⁰ to 100 mm ² / s and a pour point of −40 ° C. or less is used. When the base oil kinematic viscosity is less than 20 mm ² / s (40 ° C.), the grease becomes inferior in heat resistance, and when it exceeds 100 mm ² / s (40 ° C.), heat generation during sliding increases. A preferable base oil kinematic viscosity is 25 to 50 mm ² / s (40 ° C.). In addition, the pour point is specified because an automobile needs to withstand use near -40 ° C (engine start).

  Although there is no restriction | limiting in the kind of ester oil, Diester oil, polyol ester oil, aromatic ester oil, etc. can be used conveniently. Specific examples of diester oils include dioctyl adipate (DOA), diisodecyl adipate (DIBA), dibutyl adipate (DBA), dioctyl azelate (DOZ), dibutyl sebacate (DBS), dioctyl sebacate (DOS), and the like. be able to. Further, as a polyol ester oil, a pentaerythritol ester oil, a dipentaerythritol ester oil, a tripentaerythritol ester oil, a neopentyl diol ester oil, a trimethylolpropane ester oil, etc., into which an alkyl chain having 4 to 18 carbon atoms has been introduced. Can be mentioned. Examples of the aromatic ester oil include trioctyl trimellitate (TOTM), tridecyl trimellitate, tetraoctyl pyromellitate and the like. These ester oils may be used alone or in appropriate combination.

As the thickener, a diurea compound having excellent heat resistance is used. Particularly preferred are diurea compounds represented by the following general formula (I).
R1-NHCONH-R3-NHCONH-R2 (I)
In the formula, R1 and R2 are hydrocarbon groups having 6 to 18 carbon atoms, which may be the same or different, and R3 is an aromatic hydrocarbon group having 6 to 15 carbon atoms. Among these, diurea compounds in which R1 and R2 are cyclohexyl groups or a mixture of cyclohexyl groups and aliphatic groups are preferable. On the other hand, diurea compounds in which aromatic groups are introduced into R1 and R2 tend to be cured by heating, and may not be suitable for lubrication of sliding parts at high temperatures.

  The blending amount of the thickener is 10 to 30% by mass, preferably 15 to 25% by mass, based on the total amount of grease.

  In grease, as a first essential additive, a total of two or more selected from carboxylic acid-based rust preventives, carboxylate-based rust preventives, ester-based rust preventives and amine-based rust preventive 1 to 10% by mass of the total amount, and 0.5 to 9.5% by mass, respectively. By using these rust inhibitors in combination, particularly excellent rust prevention performance is imparted. Therefore, if the addition amount of the rust inhibitor alone and in total does not satisfy the above value, the intended purpose cannot be achieved.

  Specific examples include carboxylic acid rust preventives and carboxylate rust preventives such as stearic acid for monocarboxylic acids, alkyl or alkenyl succinic acids and their derivatives for dicarboxylic acids, naphthenic acid, and abietin. Examples thereof include metal salts such as acids, lanolin fatty acids, calcium and zinc of alkenyl succinic acid, and alkenyl succinic acid and zinc naphthenate are particularly preferable. Specific examples of the ester-based rust preventive include sorbitan monooleate, sorbitan trioleate, pentaerythritol monooleate, succinic acid half ester and the like in the carboxylic acid partial ester of polyhydric alcohol, particularly sorbitan monooleate and Succinic acid half esters are preferred. Examples of amine-based rust inhibitors include alkoxyphenylamine and dibasic carboxylic acid partial amides as amine derivatives.

  An organic molybdenum compound is added to the grease as the second essential additive together with the first essential additive. As the organic molybdenum compound, molybdenum dithiophosphate (MoDTP), molybdenum dithiocarbamate (MoDTC), an amine complex of molybdenum, and the like are preferable, and the addition amount is 1 to 10% by mass of the total amount of grease. These organic molybdenum compounds function as extreme pressure agents and contribute to the suppression of white tissue peeling. Therefore, if the addition amount is less than 1% by mass, such an effect is not sufficiently exhibited. Moreover, even if added over 10% by mass, the effect is saturated and the other components are relatively reduced, and the effect of the other components cannot be obtained.

  Moreover, you may add the various well-known additive conventionally added to grease to grease as needed.

  Grease contains each of the above components, but its production method is not limited and can be prepared in the same manner as a conventional urea grease, but in general, it is a raw material of a diurea compound (amine) in a base oil. And diisocyanate). The production conditions such as the heating temperature and stirring / mixing time at that time are appropriately set depending on the base oil and diurea compound raw materials, additives and the like to be used. Moreover, after adding an additive, it is necessary to fully stir and disperse the additive uniformly, but heating at that time is also effective.

  Examples The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited thereby.

(Examples 1-8, Comparative Examples 1-6)
Test greases were prepared with the formulations shown in Tables 1 and 2. At the time of preparation, first, a half amount of the base oil and the amine component of the thickener are placed in the first container, and the mixture is stirred while heating, and then the half amount of the base oil and 4,4′-diphenylmethane diisocyanate (Tokyo) Kasei Chemical Co., Ltd.) was added and stirred while heating, and the contents of the second container were added to the first container to react the contents of both containers. Next, an additive was added to the reaction product and finished with a three-stage roll mill to obtain a test grease.

  Then, (1) seizure test, (2) bearing peeling test and (3) bearing rust prevention test shown below were performed using the test grease. The results are shown in Tables 1 and 2.

(1) Seizure test NSK "6204VV" manufactured by NSK Ltd. is used as a test bearing, 1 g of test grease is enclosed, a preloading load of 20 kgf, and an ambient temperature of 160 ° C are used using a test apparatus having the configuration shown in FIG. It was continuously rotated to prospect for 500 hours at 6000 min ^-1. The case where it rotated without abnormality after rotating for 500 hours was regarded as acceptable. The test apparatus shown is similar to the bearing life tester of ASTM D1741.
(2) Peel resistance test A test bearing was prepared by enclosing 2.5 g of test grease in a single-row deep groove ball bearing with a rubber seal (inner diameter 17 mm, outer diameter 47 mm, width 14 mm). Then, incorporate the test bearing to the alternator of a motor vehicle engine, at room temperature atmosphere, the pulley load 1560N, repeated by continuously rotating at engine speed 1000~6000min ^-1 (bearing rpm 2400~13300min ^-1), the vibration of the defined The test was stopped when the value exceeded 50 G, and the time until that time was measured. In addition, when the vibration value was not exceeded after the elapse of 500, the test was stopped at that time. Moreover, the presence or absence of peeling of the bearing steel material was confirmed with the naked eye after the test.
(3) Bearing rust prevention test A test bearing was produced by sealing test grease with a single row deep groove ball bearing with rubber seal (inner diameter 17 mm, outer diameter 47 mm, width 14 mm) so as to occupy 50% of the bearing space volume. After enclosing, running-in (rotating) for 30 seconds at a rotational speed of 1800 min ⁻¹ , 0.5 ml of 0.5 mass% salt water was then injected into the bearing, and running ^- in again for 30 seconds at a rotational speed of 1800 min ⁻¹ . Next, the test bearing was placed in a thermo-hygrostat maintained at 80 ° C. and 100% RH and allowed to stand for 48 hours. Then, the test bearing was disassembled and the state of rust generated on the raceway surface was observed with the naked eye. The hatching criteria were as follows, and # 7 to # 5 were considered to have good rust prevention properties, and # 4 to # 1 were made to have poor rust prevention properties.
# 7: No generation of rust # 6: There is fine spot-like rust # 5: There is spot-like rust with a diameter of 0.3 mm or less # 4: Rust with a diameter of more than 0.3 mm and less than 1.0 mm # 3: Rust over 1.0 mm in diameter and 5.0 mm or less # 2: Rust over 5.0 mm in diameter and 10.0 mm or less # 1: Rust occurs on almost the entire raceway surface

  In the table, cyclohexylamine, phenothiazine and dioctyldiphenylamine are all test grades manufactured by Tokyo Ohka Co., Ltd., MoDTP is “Sakura Rube 300” manufactured by Asahi Denka Co., Ltd., and MoDTC is manufactured by Asahi Denka Co., Ltd. Sakura Lube 165 ".

  As shown in Tables 1 and 2, the test grease of each example according to the present invention is excellent in heat resistance and peel resistance, has high rust prevention performance, and is a rolling bearing for electromagnetic clutches, compressors and idler pulleys. It turns out that it is suitable for a rotation transmission device with a built-in direction clutch.

  On the other hand, the test greases of Comparative Example 1 and Comparative Example 2 containing barium sulfonate and zinc sulfonate are both inferior in peel resistance and rust resistance. The test grease of Comparative Example 3 using ether oil as the base oil and the test grease of Comparative Example 4 using poly α-olefin oil (PAO) are both inferior in durability. In addition, the test grease of Comparative Example 5 that does not contain a rust preventive agent is greatly inferior in rust prevention performance. Further, the test grease of Comparative Example 6 containing no extreme pressure agent is inferior in durability.

It is sectional drawing which shows an example of the rolling bearing for electromagnetic clutches, compressors, and idler pulleys of this invention. It is sectional drawing which shows the structure of the test apparatus used for the seizure test in the Example.

Explanation of symbols

21 Ball bearing 22 Outer ring 22a Outer ring raceway surface 23 Inner ring 23a Inner ring raceway surface 24 Ball 27 Grease

Claims (2)

In rolling bearings for electromagnetic clutches, compressors, and idler pulleys, in which a plurality of rolling elements are rotatably held between an inner ring and an outer ring, and grease is enclosed,
The grease has an ester oil having a kinematic viscosity at 40 ° C. of ²⁰ to 100 mm ² / s and a pour point of −40 ° C. or less as a base oil, and a diurea compound as a thickener is 10 to 30% by mass of the total amount of the grease. 1 to 10% by mass of the total amount of grease, and at least two types of carboxylic acid-based rust preventive, carboxylate-based rust preventive, ester-based rust preventive and amine-based rust preventive Rolling bearings for electromagnetic clutches, compressors and idler pulleys, each containing 0.5 to 9.5% by mass and an organomolybdenum compound in a proportion of 1 to 5% by mass of the total amount of grease. The one-way clutch built-in rotation transmission device according to claim 1, wherein the diurea compound is a diurea compound represented by the following general formula (I).
R1-NHCONH-R3-NHCONH-R2 (I)
(In the formula, R1 and R2 are hydrocarbon groups having 6 to 18 carbon atoms, which may be the same or different, and R3 is an aromatic hydrocarbon group having 6 to 15 carbon atoms.)

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