JP2003176831A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing used favorable, particularly in a fuel injection control device of a car, having excellent low-temperature torque performance and high-temperature durability compared with any conventional arrangement and also an excellent low-temperature torque performance and high- temperature durability in the same manner even in a type of usage where the preload is large and the bearing pressure is high. <P>SOLUTION: The rolling bearing is structured so that a grease is encapsulated therein whose base consists in perfluoropolyether oil having a straight chain structure with the 40°C dynamic viscosity ranging 20-100 mm<SP>2</SP>/s and which contains a thickening agent consisting of fluoro-resin particles and also at least one of such substances as ester series rust preventive agent, fluoride ether series diamide and fluoride ether series phosphoric acid. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an automobile, and more particularly to a rolling bearing used for an idle speed control device, an exhaust gas recirculation device, an electronic throttle control device, etc. The present invention relates to a rolling bearing for a fuel injection control device which is good and has improved low temperature torque performance and high temperature durability.

[0002]

2. Description of the Related Art Rolling bearings used in automobile fuel injection control devices such as idle speed control devices, exhaust gas recirculation devices, and electronic throttle control devices are required to have high temperature durability and low temperature torque performance. Many. Therefore, conventionally, lithium soap-ester oil-based grease, urea-synthetic hydrocarbon oil-based grease, etc. are enclosed as a lubricant, and by using synthetic oil as a base oil, high temperature durability and low temperature torque performance have been satisfied. It was When the demand for low temperature torque performance is particularly strong, lubricating oil such as ester oil or fluorine oil is used to cover the performance.

However, in recent years, performance requirements for rolling bearings used in the above fuel injection control device have become stricter. For example, in an exhaust gas recirculation device, in order to further reduce NOx contained in the exhaust gas of the engine. ,
The exhaust gas immediately after combustion is recirculated, and the rolling bearing used therein is kept at a high temperature of about 200 ° C.
Along with this, the lithium soap-ester oil-based grease, urea-synthetic hydrocarbon oil-based grease, or lubricating oil such as ester oil or fluorine oil, which has been conventionally sealed, cannot maintain high-temperature durability.

In order to meet such demands, the present applicant uses polytetrafluoroethylene particles having an average particle size of 0.1 μm or less as a thickener, as disclosed in JP-A-2000-119673. We have proposed a rolling bearing with high-temperature durability and low-temperature torque performance improved by encapsulating fluorine grease. However, the fluorine-based grease has a room for improvement in rust-preventing performance because it is difficult to add a rust-preventive additive to other greases.

Further, the rolling bearing used in the above fuel injection control device is often used in a state in which a relatively large preload is applied, and polytetrafluoroethylene particles which are a thickener at the time of use, and further solid state. When the additive is added, this solid additive easily enters the bearing rolling surface, so that a so-called "rigid feeling" or "torque spike" is likely to occur.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation and has excellent low temperature torque performance and high temperature durability as compared with the conventional one, and further has a large preload and a high surface pressure. It is an object of the present invention to provide a rolling bearing that has excellent low temperature torque performance and high temperature durability even in the following usage form and is particularly suitable for a fuel injection control device of an automobile.

[0007]

The present invention has been completed as a result of extensive studies to solve the above-mentioned problems, and is completed in a low temperature range (about -40 ° C) to a high temperature range (about 200 ° C). In addition, in order to satisfy the excellent torque performance and durability even in the usage mode in which a preload is applied, the present invention is
A perfluoropolyether oil having a linear structure with a kinematic viscosity at 40 ° C. of 20 to 100 mm ² / s is used as a base oil, fluororesin particles are used as a thickener, and an ester rust preventive agent, a fluorinated ether diamide and Provided is a rolling bearing, which is filled with grease containing at least one selected from fluorinated ether phosphoric acid.

In the above description, the perfluoropolyether oil having a straight-chain structure as a base oil is superior in heat resistance to that having a branched structure, has sufficient heat resistance even at a high temperature exceeding 200 ° C., and has a viscosity. The index is high and the viscosity does not easily change with temperature. Moreover, since the kinematic viscosity at 40 ° C. is in the range of ²⁰ to 100 mm ² / s,
It contributes to the improvement of torque performance in the low temperature range. Further, the fluororesin particles which are thickeners also have heat resistance. Furthermore, the ester-based rust preventive has a high affinity with the above-mentioned base oil and thickener, and can impart good rust preventive performance to grease. Further, the fluorinated ether-based diamide and the fluorinated ether-based phosphoric acid have a function as an oiliness agent, and are adsorbed on the raceway surface and rolling surface of the bearing to improve lubricity, and are effective in reducing torque. .

Therefore, by enclosing the above-mentioned specific grease, the bearing can maintain good bearing characteristics in a low temperature range to a high temperature range for a long period of time.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The rolling bearing of the present invention is not limited in its structure and construction, and is a rolling bearing conventionally used for an idle speed control device, an exhaust gas recirculation device, an electronic throttle control device, etc. of an automobile. Can be targeted. For example, FIG. 1 is a cross-sectional view showing an example thereof, but the rolling bearing 1 is formed between an outer ring raceway 12a formed on the inner peripheral surface of the outer ring 12 and an inner ring raceway 13a formed on the outer peripheral surface of the inner ring 13. In addition, the plurality of rolling elements 14 are attached to the cage 1
5, a seal 16 is held so that it can be rolled by 5 and is fixed to the mounting groove 12b of the outer ring 12, and a grease 17 described in detail below is sealed.

The base oil of the grease is not particularly limited as long as it is a perfluoropolyether oil having a straight chain structure. For example, the perfluoropolyether oil represented by the following formulas (1) to (3) Is preferred.

[0013]

[Chemical 1]

Considering the torque performance in the low temperature range, the kinematic viscosity at 40 ° C. is preferably 100 mm ² / s or less. On the other hand, from the viewpoint of high temperature durability, the kinematic viscosity at 40 ° C. is 20 mm ² / s or more, especially 30 mm ² / s.
The above is preferable.

These linear structure perfluoropolyether oils can be used alone or in combination.

The thickener has a high affinity with the perfluoropolyether oil having the above-mentioned linear structure, and has a high temperature stability,
Fluororesin particles having chemical resistance and acid resistance are preferable.
For example, particles made of tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polytetrafluoroethylene (PTFE), or the like can be used.
E particles are preferred. Further, the larger the diameter of the PTFE particles, the more the torque tends to increase, and the torque tends to increase particularly at low temperatures. Therefore, the average particle diameter is preferably 0.3 μm or less, and 0.1 μm or less is preferable. More preferable. Further, the PTFE particles, as long as they satisfy this particle size,
The shape is not particularly limited, and may be spherical, polyhedral (cubic or rectangular parallelepiped), or extremely needle-shaped.

These fluororesin particles may be used alone or as a mixture. The blending amount is N, which is the grade in which the blending consistency when used as grease is specified by NLGI.
o. 1-No. 3, preferably No. 3 1-No. It is preferable to add an amount of 2 so that the fluidity suitable for the present invention can be provided.

Further, the grease contains an ester type rust preventive,
At least one selected from a fluorinated ether diamide and a fluorinated ether phosphoric acid is added.

The ester type rust preventive agent is not particularly limited as long as it is a liquid at room temperature, but in consideration of heat resistance, N-type shown below is used.
It is preferable to use an acyl-N-hydrocarbonoxyalkylaspartic acid ester metal salt. In the formula, M represents a metal species, specifically Sb, Bi, Sn, N
It is selected from i, Te, Se, Fe, Cu, Mo, Zn, Ca and the like. Alternatively, an amine salt such as NH ₃ can be used.

[0020]

[Chemical 2]

The amount of the ester-based rust preventive added is 0.1% by mass or more, preferably 0.5% by mass, based on the total amount of grease.
The above is preferable. If the addition amount is less than 0.1% by mass, the rust prevention performance will be insufficient. The upper limit of the amount added is 10% by mass, especially 8% by mass, based on the total amount of grease. Even if the amount added exceeds 10% by mass, the effect commensurate with the increment cannot be obtained, but rather the torque increases. If so, the heat resistance may be reduced.

As the fluorinated ether type diamide, those represented by the following general formula (A) are preferable.

[0023]

[Chemical 3]

Here, R is an alkyl group having 1 to 30 carbon atoms, a cyclohexyl group having 6 to 12 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms. Rf ₀ is a fluorinated ether ether group represented by the following (m is 1 to 5)
0).

[0025]

[Chemical 4]

As the fluorinated ether phosphoric acid,
What is represented by the following general formula (B) is preferable.

[0027]

[Chemical 5]

Here, R is an alkyl group having 1 to 30 carbon atoms, a cyclohexyl group having 6 to 12 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms. Rf ₀ is a fluorinated ether ether group represented by the following (m is 1 to 5)
0).

[0029]

[Chemical 6]

The fluorinated ether type diamide and the fluorinated ether type phosphoric acid may be added alone or in a mixture.
In any case, the added amount is 0.1 to 1 with respect to the total amount of grease.
It is 0 mass%. Fluorinated ether type diamide and fluorinated ether type phosphoric acid have a function as an oiliness agent,
If the addition amount is less than 0.1% by mass, it will be difficult to reduce the torque. On the other hand, if the addition amount exceeds 10% by mass, the viscosity of the base oil becomes high, and conversely the torque becomes high.

It is also possible to add an ester type rust preventive and at least one of a fluorinated ether diamide and a fluorinated ether phosphoric acid in combination. As a result, it is possible to achieve low torque as well as rust prevention performance.
Therefore, in order to effectively obtain both effects, it is preferable to add the ester-based rust preventive agent and at least one of the fluorinated ether diamide and the fluorinated ether phosphoric acid in equal amounts. In this case, the total amount of addition is preferably 0.2 to 15% by mass of the total amount of grease. The lower limit of the addition amount of 0.2% by mass is the total of the lower limit of the addition amount of the ester rust preventive agent and the lower limit of the addition amount of the fluorinated ether diamide and the fluorinated ether phosphoric acid. If it is less than this value, improvement in rust prevention performance and reduction in torque cannot be realized at the same time. If the addition amount exceeds 15% by mass, the torque is increased.

Further, various other additives may be added to the above grease within a range not impairing the effects of the present invention.

The above-mentioned grease can be produced by a known method. For example, at least one of a thickener, an ester rust preventive, a fluorinated ether diamide and a fluorinated ether phosphoric acid is added to a base oil and heated. After the semi-solid substance obtained by stirring is gradually cooled, various additives are added if necessary and the mixture is uniformly kneaded by a roll mill or the like. At this time, various conditions such as heating temperature and stirring / kneading time depend on the base oil and thickener used, ester rust inhibitor, fluorinated ether diamide, fluorinated ether phosphoric acid, and other additives. It is set appropriately.

[0034]

The present invention will be further described below with reference to examples, but the present invention is not limited to these examples.

[Test-1: Ester Corrosion Inhibitor] (Preparation of Grease) Grease A: 40 having a molecular structure (1) shown in Table 1.
For base oil having a kinematic viscosity at 10 ° C of 10 to 150 mm ² / s,
PTFE particles (average particle size 0.1 μm) and rust preventive agent (1)
Was added by 1% by mass, and the semi-solid product obtained by stirring and heating was gradually cooled and then obtained through a roll mill. In addition, the workability is NLGI No. It was set to 1. -Grease B: having the molecular structure (2) shown in Table 1, 40
PTFE was added to base oil with a kinematic viscosity at 85 ° C of 85 mm ² / s.
Add particles (average particle size 0.1 μm) and rust preventive agent (1) to 0.0
5-12 mass% was added, and the semi-solid product obtained by stirring and heating was gradually cooled and then obtained through a roll mill. In addition, the workability is NLGI No. It was set to 2. Grease C: having the molecular structure (2) shown in Table 1, 40
PTFE was added to base oil with a kinematic viscosity at 85 ° C of 85 mm ² / s.
NaNO as particles (average particle size 0.1 μm) and rust inhibitor
0.05 to 0.5 mass% of ₂ was added, and the semi-solid product obtained by stirring and heating was gradually cooled and then obtained through a roll mill.
In addition, the workability is NLGI No. It was set to 2.

The compositions of Grease A, Grease B and Grease C described above are summarized in Table 2.

[0037]

[Table 1]

[0038]

[Table 2]

(Low temperature torque test-1) The grease A described above was sealed in a deep groove ball bearing with a steel shield plate (inner diameter φ8, outer diameter φ16, width 4 mm) so as to occupy 30% of the bearing space volume. Then, after rotating at 1800 min ⁻¹ for 30 seconds, it was left in a constant temperature bath at −40 ° C. for 4 hours, and then the dynamic torque value was measured when the inner ring was rotated at 300 min ⁻¹ for 3 minutes. This dynamic torque value is 0.01N
m or more was disallowed. The test was conducted three times for each grease, and the results are shown in FIGS.

(High Temperature Durability Test) The above grease A was enclosed in a deep groove ball bearing with a steel shield plate (inner diameter φ17, outer diameter φ40, width 12 mm) so as to occupy 35% of the bearing space volume. And bearing temperature 200 ℃, inner ring rotation speed 6
The bearing was continuously rotated under the conditions of 000 min ⁻¹ and an axial load of 196N. The time required for the temperature of the bearing to rise to 210 ° C. (seizing time) was measured. This burning time is
Pass for 300 hours or more. The test was performed 3 times for each grease, and the results are shown in FIG.

From FIG. 2, the kinematic viscosity of the base oil of the grease is 20
It is understood that both the low temperature torque performance and the high temperature durability performance are satisfied in the range of up to 100 mm ² / s (40 ° C.).

(Verification of Addition Amount) Using Grease B and Grease C described above, the same low temperature torque test was conducted.
The results are shown in Fig. 2. The amount of the ester-based rust preventive added was 10
If it is less than mass%, the torque value is 0.01 N · m or less, and it is understood that the low temperature torque performance is satisfied. On the other hand, a rust preventive which is not an ester rust preventive cannot provide satisfactory low temperature torque performance even in a very small amount.

(Rust prevention test) 2.3 g of the above grease B or grease C was filled in a deep groove ball bearing with a circular contact rubber seal (inner diameter φ17, outer diameter φ47, width 14 mm).
Then, after rotating at a rotation speed of 1800 min ^-1 for 1 minute, 0.5 cc of pure water was injected into the bearing and again rotated at a rotation speed of 1800 min ^-1 for 1 minute. Then 50
After being left for 120 hours under the conditions of ℃ and 95% HR, the rusting condition of the inner and outer raceways of the bearing was observed. The evaluation was performed according to the criteria shown in Table 3, and a rust evaluation score of 2 or less was regarded as a pass.

[0044]

[Table 3]

The results are shown in FIG. 3, and it can be seen that by adding 0.1% by mass or more of the ester-based rust preventive agent, excellent rust preventive performance can be imparted.

[Test-2: Fluorinated ether diamide,
Fluorinated ether phosphoric acid] (Preparation of grease) Grease D: having a molecular structure shown in Tables 4 and 5 and 4
Base oil 1 with a kinematic viscosity at 0 ° C of 90 mm ² / s, PT
Add FE particles (average particle size 0.1 μm) and additive 1 to 0.0
5-12 mass% was added, and the semi-solid product obtained by stirring and heating was gradually cooled and then obtained through a roll mill. In addition, the workability is NLGI No. It was set to 1. Grease E: 4 having a molecular structure shown in Tables 4 and 5
PT was added to base oil 2 with a kinematic viscosity of 85 mm ² / s at 0 ° C.
Add FE particles (average particle size 0.1 μm) and Additive 2 to 0.0
5-12 mass% was added, and the semi-solid product obtained by stirring and heating was gradually cooled and then obtained through a roll mill. In addition, the workability is NLGI No. It was set to 2.

[0047]

[Table 4]

[0048]

[Table 5]

(Low temperature torque test-2) A deep groove ball bearing with a steel shield plate (inner diameter φ8, outer diameter φ16, width 4 mm) was filled with each of the above greases so as to occupy 30% of the bearing space volume, and 1800 min ^−1. After rotating for 30 seconds,
The kinetic torque value was measured when left in a constant temperature bath of 40 ° C. for 4 hours and then rotated for 3 minutes at an axial load of 108 N and an inner ring rotation speed of 10 min ⁻¹ . This dynamic torque value is
0.01 N · m or more was disallowed. The test was performed 3 times for each grease, and the results are shown in FIG.

As shown in FIG. 4, both the fluorinated ether diamide and the fluorinated ether phosphoric acid have a torque value of 0.01 N · m or less when the addition amount is 0.1 to 10 mass% or less, and the low temperature torque is low. It can be seen that the performance is satisfied. Further, when the addition amount is 10% by mass, there is a difference ΔA from the reference value (0.01 N · m), but in FIG.
The amount of addition of the ester rust preventive agent whose difference ΔB from N · m) is smaller than this ΔA is in the range of 5% by mass or less. Therefore, as long as the ester rust preventive agent and at least one of the fluorinated ether diamide and the fluorinated ether phosphoric acid are added in a total amount of 15% by mass or less based on the total amount of the grease, low torque It can be seen that

[0051]

As described above, the rolling bearing of the present invention has a perfluoropolyether oil having a specific kinematic viscosity and a linear structure, fluororesin particles such as PTFE, an ester-based rust preventive agent, and a fluorine-containing agent. By encapsulating a grease containing at least one of a fluorinated ether diamide and a fluorinated ether phosphoric acid, both low-temperature torque performance and high-temperature durability are improved, and since it also has excellent rust prevention performance,
For example, idle speed control device and exhaust gas recirculation device,
Stable bearing performance is required from a low temperature range to a high temperature range, such as used in a vehicle fuel injection control device such as an electronic throttle control device, and is useful as a rolling bearing used under a preload condition. .

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a rolling bearing of the present invention.

FIG. 2 is a graph showing the relationship between kinematic viscosity of base oil, torque, and seizure time obtained in Test-1.

FIG. 3 is a graph showing the relationship between the addition amount of a rust preventive agent, torque, and rust generation state obtained in Test-1.

FIG. 4 is a graph showing the relationship between the additive amount and torque obtained in Test-2.

[Explanation of symbols]

1 Rolling bearing 12 outer ring 13 inner ring 14 rolling elements 15 cage 16 seals 17 grease

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C10M 149/12 C10M 149/12 153/04 153/04 169/02 169/02 F16C 25/06 F16C 25 / 06 // C10N 20:02 C10N 20:02 40:02 40:02 50:10 50:10 (72) Inventor Mitsuru Saito 1-5-50 Kumeiuma Kugenuma, Fujisawa-shi, Kanagawa NSK Ltd. (72) Inventor Nobuaki Izawa 1-5-50 Shinmei Kugenuma, Fujisawa-shi, Kanagawa NSK Ltd. (72) Inventor Mamoru Sato 1-5-50 Kumei, Kugenuma, Fujisawa-shi, Kanagawa F-Term (reference) 3J012 AB04 AB12 BB01 EB14 FB10 HB01 3J101 AA02 AA32 AA42 AA52 AA62 CA12 CA32 EA64 FA06 FA08 FA32 GA01 4H104 BE11C BH11C CD01B CD02B CD04A CD04B CE19C CH09C EA02A PA01 QA18

Claims (5)

[Claims] 1. A kinematic viscosity at 40 ° C. of 20 to 100 m.
Perfluoropolyether oil having a linear structure at m ² / s is used as a base oil, fluororesin particles are used as a thickening agent, and selected from ester rust preventives, fluorinated ether diamides and fluorinated ether phosphoric acids. A rolling bearing characterized in that a grease containing at least one of the above is enclosed. 2. The rolling bearing according to claim 1, wherein the amount of the ester-based rust inhibitor added is 0.1 to 10% by mass based on the total amount of grease. 3. The addition amount of the fluorinated ether diamide and the fluorinated ether phosphoric acid is 0.1 to 10% by mass in total with respect to the total amount of grease. Rolling bearing. 4. The grease comprises an ester rust preventive agent and at least one of a fluorinated ether diamide and a fluorinated ether phosphoric acid in a total amount of 0.
The rolling bearing according to claim 2, wherein the rolling bearing contains 2 to 15 mass%. 5. The rolling bearing according to claim 1, wherein the rolling bearing is used under a preload.