JP5145696B2 - Rolling device - Google Patents

Description

The present invention is a rolling device encapsulating off Tsu Motokei grease composition, rolling relates particularly used in electronic control motor of the motor vehicle.

  Used in automotive electronic parts such as motors for electronic control devices such as electronic throttle, idle rotation control valve (ISCV), exhaust gas recirculation device (EGR), electric fan motor, fluid coupling for cooling fan, powder clutch, etc. Rolling bearings used in office automation equipment such as rolling bearings, hard disk drives (HDD), laser beam printers (LBP), and copiers are often required to have durability at high temperatures and torque performance at low temperatures. In general, grease compositions using an ether oil-based lubricating oil excellent in heat resistance as a base oil are used.

  In recent years, automobiles have been forced to reduce the engine room due to a request for expansion of the interior space, and the above-mentioned automotive electrical components are also becoming smaller and lighter, but we are addressing this by speeding up the decline in performance. Furthermore, the engine room is also being sealed due to the demand for improved inertia. The same is true for rolling bearings used in OA equipment, and they are rotated at high speeds as they become smaller and lighter. For this reason, rolling bearings used in automotive electrical parts and OA equipment are required to have further heat resistance, and particularly in parts exposed to high temperatures of 160 ° C. or higher, silicone oils and fluorine having higher heat resistance are required. A grease composition using an oil-based lubricating oil as a base oil is used.

  By the way, in rolling bearings filled with a grease composition, a seal bearing or a shield bearing structure is adopted, and a slinger is additionally provided to prevent the grease composition from leaking to the outside and prevent the entry of substances from the outside. ing. However, rolling bearings cannot be completely sealed even if they have the structure and members described above, and therefore intrusion of substances from the outside is inevitable.

  These externally infiltrated substances contain substances and moisture that are sources of rust, and condensation may occur due to rapid temperature changes, so the grease composition to be used must have rust prevention performance. Is indispensable.

  In order to impart rust prevention performance, a rust inhibitor is usually added to the grease composition. Various substances are known as rust preventives, and nitrite and organic sulfonic acid metal salts are widely used as those particularly excellent in rust prevention performance.

  However, nitrite is not preferred because it may produce amines that are carcinogenic when used at high temperatures, and even when used, its amount may be limited, and its rust prevention performance is not fully demonstrated. In some cases.

  Moreover, a rust preventive agent expresses rust prevention property by forming a corrosion-resistant film on the metal surface. Therefore, in order to form a uniform anticorrosive coating on the bearing raceway and the entire rolling element, it is necessary for the rust inhibitor to dissolve in the base oil. Grease compositions based on oil-based lubricating oils cannot be used because the organic sulfonic acid metal salt is insoluble in these base oils. Therefore, grease compositions based on silicone oils or fluorine oils are addressed by adding fluorine compounds having functional groups such as carbonyl groups, alcohol groups, and ester groups in the skeleton. These fluorine compounds have low rust prevention performance, and it cannot be said that they can withstand practical use.

  Against this background, the applicant previously added a vaporizable rust preventive agent and a magnesium compound to a grease composition based on a silicone oil or a fluorine oil-based lubricating oil. Proposes to improve rust prevention performance (see Patent Document 1)

JP 2004-176075 A

  However, in the grease composition described in Patent Document 1, powders such as magnesium oxide are used as the magnesium compound. However, these are hard materials, and thus damage the surface of the components of the rolling device. There is a risk of rusting.

  In addition, in order to reduce energy loss and to ensure sufficient operability even in low temperature environments of -30 ° C or lower, especially for automotive electrical components, the performance is low torque over a wide temperature range and the torque stabilizes quickly (torque stability Performance) is also required, but there is room for improvement in this respect as well.

Therefore, the present invention is not only durable at high temperatures but also excellent in rust prevention performance, and further encapsulated with a fluorine-based grease composition that has low torque over a wide temperature range and excellent torque stability performance, and has heat resistance and rust prevention performance. Another object of the present invention is to provide a rolling device that has excellent torque and stable torque in a wide temperature range from low temperature to high temperature with low torque.

In order to achieve the above object, the present invention provides the following rolling device.
(1) A roll comprising a fluorine grease composition containing sodium sebacate and hydrophilic silica particles having a primary particle diameter of 50 nm or less, which is obtained by increasing fluorine lubricant with a thickener. Moving device.
(2) The rolling device according to (1) above, wherein the content of sodium sebacate in the fluorine-based grease composition is 0.5 to 10% by mass.
(3) The rolling device according to (1) or (2) above, wherein the content of hydrophilic silica particles in the fluorine-based grease composition is 0.01 to 5% by mass.
(4) The rolling device according to any one of (1) to (3), wherein the rolling device is incorporated in a motor for an electronic control device of an automobile.

In the fluorinated grease composition used in the present invention , the fluorinated lubricating oil of the base oil ensures heat resistance, and high rust prevention performance is imparted by sodium sebacate . Further, by using hydrophilic silica particles having a primary particle diameter of 50 nm or less in combination, the fluidity of the grease is improved, the torque is reduced, and the torque stability performance is enhanced. In addition, since the hydrophilic silica particles are minute, there is little wear on the lubrication points.

Therefore, the rolling apparatus of the present invention encapsulating above fluorine-based grease composition has excellent heat resistance and rust performance, shows a stable rotational performance over a wide temperature range from a low temperature in a low torque to a high temperature.

  Hereinafter, the present invention will be described in detail.

In the fluorine-based grease compositions used in the present invention is the base oil may be used a fluorine-based lubricating oil which has been used traditional in the fluorine-based grease compositions, branched or straight-chain fluoropolyether oils (PFPE) Can be preferably used, and each can be used alone or in combination. In particular, linear PFPE is more preferable because of its high viscosity index and excellent fluidity at an extremely low temperature of −30 ° C. or lower. In addition, as a viscosity index, 100-400 are preferable and it is more preferable that it is 200-400. Moreover, in order to suppress seizure that occurs due to generation of abnormal noise at low temperature startup and oil film formation at high temperatures, the base oil preferably has a kinematic viscosity at 40 ° C. of ²⁰ to 400 mm ² / s, It is more preferable that it is 30-200 mm < ² > / s.

  The thickener is not limited, and those conventionally used in fluorine-based grease compositions can be used, but polytetrafluoroethylene powder and polytetrafluoroethylene suspension can be suitably used. Further, the amount of the thickener is not limited as long as the grease can be formed and maintained together with the above base oil, and the range of 5 to 40% by mass of the total amount of grease is appropriate.

Off Tsu Motokei grease composition, containing sodium sebacate. Sodium sebacate is adsorbed on the surface of the constituent member of the rolling device by electrical interaction and has a function of imparting rust prevention performance by forming a film. Further, sodium sebacate can be uniformly dispersed in the fluorine-based lubricating oil. Furthermore , sodium sebacate has a melting point of 250 ° C. or higher , maintains a solid state even when exposed to a high temperature of about 200 ° C. , and does not impair dispersibility in the fluorinated lubricant, and has rust prevention performance. It can be maintained well. The content is preferably 0.5 to 10% by mass of the total amount of grease, and more preferably 2 to 10% by mass.

Also, full Tsu Motokei grease composition, in addition to sodium sebacate above, containing a hydrophilic silica particles primary particle diameter of 50nm or less. The hydrophilic silica particles improve the fluidity of the grease, resulting in a low torque and an increased torque stability. Large particles having a primary particle diameter of more than 50 nm come to act as an abrasive and may damage the surface of the constituent members of the rolling device. Moreover, it is preferable that the primary particle diameter of hydrophilic silica particle is 3-50 nm, and it is more preferable that it is 3-20 nm. If the thickness is less than 3 nm, hydrophilic silica particles aggregate in the grease, making it difficult to stably disperse in the grease.

There is one as channeling of grease characteristics that affect bearings torque performance (a phenomenon that may groove through which a rolling element rolling run side), the more likely it is a groove through which a the higher the tea nen ring resistance (rolling elements ), The torque stability performance of the bearing torque is increased. In addition, the channeling property is improved by strengthening the grease structure and optimizing the grease flow characteristics. Further, the formation of a strong grease film with excellent friction and wear characteristics on the bearing surface reduces the steady torque and improves the wear resistance and seizure resistance . Silica Parent aqueous excellent in the effect to strengthen the grease structure, optimizing grease flow characteristics, Ru superior forming ability of the grease film. Moreover, as shown in the Example mentioned later, the combination of the hydrophilic silica particle whose primary particle diameter is 12 nm, and sodium sebacate has especially high synergistic effect with respect to rust prevention performance and a torque characteristic.

The hydrophilic silica particles having a primary particle size of 50 nm or less are obtained by vapor phase methods such as chemical vapor deposition (CVD) and physical vapor deposition (PVD), coprecipitation, metal alkoxide, sol- It can be easily produced using a liquid phase method such as a gel method.

Amount of the hydrophilic silica particles, Ri 0.01-5% by mass of the grease total amount, and more preferably 0.05 to 1 mass%. In particular, when it is added in a large amount exceeding 5% by mass, the hydrophilic silica particles tend to aggregate in the grease, which may adversely affect the wear resistance and seizure resistance.

The full Tsu Motokei grease composition, may be added other additives as necessary. For example, a vaporizable rust preventive agent such as benzotriazole can be used in combination, and an appropriate amount of an antioxidant, an oiliness improver, or the like blended in a normal grease composition may be blended.

Off Tsu Motokei grease composition, the thickener was added to the base oil, heat, a semi-solid product obtained by stirring, was gradually cooled, sodium sebacate and hydrophilic silica particles, other additives And uniformly mixed by a roll mill or the like.

  In addition, although there is no restriction | limiting in the penetration degree, it is preferable to set it as 235-280.

The rolling device of the present invention, ing encapsulating the above fluorine-based grease compositions. Since the above-mentioned fluorine-based grease composition has low torque and excellent heat resistance and rust prevention performance, it is particularly suitable as a rolling bearing for use in motors for electronic control throttles, automobile electronic control devices such as ISCV and EGR. . In addition, there is no restriction | limiting in the structure of rolling bearing itself, For example, a ball bearing as shown by sectional drawing in FIG. 1 can be illustrated. In this ball bearing, a plurality of balls 5 are rotatably held via a cage 7 between an inner ring 2 having an inner ring raceway surface 1 and an outer ring 4 having an outer ring raceway surface 3. The shield 6 is fixed, and the above-mentioned fluorine-based grease composition is filled in a bearing space formed by the inner ring 2, the outer ring 4, and the balls 5, although illustration is omitted.

EXAMPLES The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In Examples 1-4, Comparative Examples 1-2, Examples 13-16 and Comparative Examples 6-7 Ru Reference Example der to verify the effect of sodium sebacate.

(Examples 1-4, Comparative Examples 1-2)
As shown in Table 1, a test grease was prepared by blending a base oil, a thickener, and sodium sebacate. The test grease was subjected to the following (1) rust prevention test and (2) low temperature torque test. The results are also shown in Table 1.
(1) Rust prevention test 0.2 g of test grease is sealed in a deep groove ball bearing manufactured by NSK Ltd. (nominal number 608: inner diameter 8 mm, outer diameter 22 mm, width 6 mm), an axial load of 29.4 N, and a rotational speed of 1800 min ^{− 1. After} rotating at room temperature for 5 minutes to uniformly disperse the grease in the bearing, the grease was placed in a constant temperature and humidity chamber and allowed to stand at 80 ° C. and 90% for 300 hours. The bearings were disassembled after being left, and the inner ring running surface was observed with a stereomicroscope (× 5 times) to evaluate the occurrence of rust. The evaluation was made into a three-step evaluation where A was no rust generation, B was rust generation, and C was rust generation on the entire surface.
(2) Low temperature torque test A test grease is sealed in a rolling bearing with a shield plate having an inner diameter of 8 mm, an outer diameter of 22 mm, and a width of 7 mm so as to be 30% of the bearing space volume, and the inner ring rotational speed is 1800 min ⁻¹ , the ambient temperature is −40 ° C. The rotational torque when rotated for 10 minutes with a radial load of 0 and an axial load of 29.4 N was measured. The results are shown as relative values with the measured value of Comparative Example 1 being 1.

  From Table 1, it can be seen that the addition of sodium sebacate according to the present invention increases the rust prevention performance and low-temperature torque characteristics.

(Examples 5 to 8, Comparative Example 3, Reference Example 1)
As shown in Table 2, a test grease was prepared by blending base oil, a thickener, sodium sebacate, and hydrophilic silica particles having a primary particle size of 12 nm. The test grease was subjected to the following (3) normal temperature torque test in addition to the above (1) rust prevention test and (2) low temperature torque test. The results are also shown in Table 2. In addition, Reference Example 1 contains only sodium sebacate in accordance with the present invention and corresponds to the test grease of Example 2 above, but is included for comparison of the effect when silica fine particles are further added. is there.
(3) Normal temperature torque test In a rolling bearing with a shield plate with an inner diameter of 8 mm, an outer diameter of 22 mm, and a width of 7 mm, the test grease is sealed to 30% of the bearing space volume, the inner ring rotational speed is 1800 min ⁻¹ , the ambient temperature is 30 ° C., radial It was rotated at a load of 0 and an axial load of 29.4 N, and the torque half-life (time until the intermediate value between the starting torque value and the steady torque value) was obtained. In addition, a result is shown by the relative value which sets the measured value of the reference example 1 to 1.

  From Table 2, it can be seen that by further blending silica particles having a primary particle diameter of 12 nm, the torque characteristics are further improved as compared with the case where only sodium sebacate is blended (Reference Example 1).

(Examples 9 to 13, Comparative Examples 4 to 5)
As shown in Table 3, a test grease was prepared by blending a base oil, a thickener, sodium sebacate, and hydrophilic silica particles having a primary particle size of 12 nm. The test grease was subjected to the above (1) rust prevention test and (3) normal temperature torque test. The results are also shown in Table 3.

  The test greases of Examples 9 to 13 were obtained by changing the base oil to a mixed oil of branched PFPE and linear PFPE in the above test greases of Examples 5 to 9, and having a large kinematic viscosity at 40 ° C. Although the results of the normal temperature torque test are slightly inferior, the rust prevention performance is equivalent. From this, it can be said that the base oil is preferably linear PFPE rather than branched PFPE.

(Examples 13-16, Comparative Examples 6-7)
As shown in Table 4, a test grease was prepared by blending base oil, thickener, sodium sebacate, and magnesium oxide particles. The test grease was subjected to the following (4) abrasion test in addition to the above (1) rust prevention test. The results are also shown in Table 4. (4) Wear test Using a four-ball tester, the wear resistance of the test grease was evaluated. The ball was tested using a 1/2 inch SUJ2 ball under conditions of surface pressure of 1.6 GPa, sliding speed of 0.38 m / s, and 1 hour. Were measured in the X direction and Y direction, respectively, and the average value thereof was defined as the wear scar diameter value. A relative value with the wear scar diameter value of Comparative Example 4 as 1.

  As shown in Table 4, when Example 14 and Comparative Example 7 having the same blending amount are compared, it can be seen that sodium sebacate is more effective in improving rust prevention performance than magnesium oxide. Magnesium oxide particles are a hard material, so the amount of wear is large, but sodium sebacate has little wear.

From the above test results, the antirust performance and torque characteristics are further improved by adding sodium sebacate , and the torque characteristics are further improved by using hydrophilic silica particles having a primary particle diameter of 50 nm or less in combination. I understand.

It is sectional drawing which shows the ball bearing which is an example of the rolling device of this invention.

Explanation of symbols

1 inner ring raceway surface 2 inner ring 3 outer ring raceway surface 4 outer ring 5 ball 6 shield 7 cage

Claims (4)

  A rolling device comprising a fluorine grease composition containing sodium sebacate and hydrophilic silica particles having a primary particle diameter of 50 nm or less, which is obtained by increasing fluorine lubricant with a thickener.   The rolling device according to claim 1, wherein the content of sodium sebacate in the fluorine-based grease composition is 0.5 to 10% by mass. The rolling device according to claim 1 or 2, wherein the content of hydrophilic silica particles in the fluorine-based grease composition is 0.01 to 5 mass%.   The rolling device according to any one of claims 1 to 3, wherein the rolling device is incorporated in a motor for an electronic control device of an automobile.

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