JP5988376B2 - Grease composition and bearing for main motor bearings of railway vehicles - Google Patents

Description

  The present invention relates to a grease for a main motor bearing of a railway vehicle, and relates to a lubricating grease composition that exhibits an excellent lubricating life even under high temperature and high speed conditions.

There is a growing need for environmentally friendly main motors for railway vehicles, such as speeding up, energy saving, noise reduction, and maintenance saving. Induction motors, which are currently mainstream of main motors, have been reduced in size, weight, and output, but on the other hand, due to stricter use conditions, there is a problem that heat generation of the bearing is large. Further, since the movable part is only the bearing part, the maintenance cycle depends on the life of the bearing.
A hydroxy fatty acid having 12 to 24 carbon atoms having one or more hydroxyl groups and a lithium salt of an aliphatic dicarboxylic acid having 2 to 12 carbon atoms is used as a thickener, and the kinematic viscosity at 40 ° C. is 300 to 500 mm ² / and s oil and 40 ° C. kinematic viscosity of 80~300mm ² / s of the oil and 40 ° C. kinematic viscosity of 20 to 80 mm ² / s of the essential components a and and the ternary three component essential component of the oil The use of oil with a kinematic viscosity at 40 ° C of 80 to 200 mm ² / s as the base oil has been proposed to extend the lubrication life of bearings at high temperatures and high speeds, and to reduce the heat generated by the bearings. (Patent Document 1).
Reducing bearing heat generation is important for extending the lubrication life of the bearing. However, the motor itself generates heat, and as a result, the bearing part is also exposed to high temperatures. It will deteriorate to a seizure life.
As high-temperature and high-speed grease, synthetic oil urea grease is often used for automobile electrical equipment and auxiliary bearings, but the main motor uses cylindrical roller bearings. This lubrication is satisfactory with urea grease. Cannot get a lifetime.

Japanese Patent Laid-Open No. 03-220297

  The problem to be solved by the present invention is to provide a grease composition for a main motor bearing of a railway vehicle that has excellent heat resistance and a long bearing lubrication life so as to meet the demand for further speedup and maintenance cycle extension of the railway vehicle. It is to be.

As a result of intensive studies by the present inventors, it is possible to reduce the bearing temperature rise by using a three-component base oil having a high viscosity, a medium viscosity and a low viscosity, and an amine antioxidant and a hindered It has been found that the combined use with a phenolic antioxidant significantly improves the heat resistance of the grease composition compared to when each of them is used alone, and as a result, the bearing lubrication life can be extended.
That is, according to the present invention, the following grease composition and bearing are provided:
1. (a) a thickener comprising a lithium salt of a C12-24 hydroxy fatty acid having one or more hydroxyl groups and a C2-12 fatty acid dicarboxylic acid;
(b) and 40 ° C. oil kinematic viscosity of 300 to 500 mm ² / s of the 40 ° C. oil kinematic viscosity of 80~300mm ² / s, the kinematic viscosity of 40 ° C. and the oil 20 to 80 mm ² / s A base oil having a kinematic viscosity at 40 ° C. of 80 to 200 mm ² / s,
(c) an amine-based antioxidant, and
(d) A grease composition for a main motor bearing of a railway vehicle containing a hindered phenol-based antioxidant.
2. (c) is selected from the group consisting of p, p'-dioctyldiphenylamine, N-phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine and mixtures of two or more thereof;
(d) is 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), benzenepropanoic acid, 3 , 5-bis (1,1-dimethyl-ethyl) -4-hydroxy C7-C9 side chain alkyl ester, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and two of these Selected from the group consisting of mixtures of more than species,
2. The grease composition according to 1 above.
3. (c) is p, p'-dioctyldiphenylamine, and
The grease composition according to the above item 2, wherein (d) is 2,6-di-tert-butyl-4-methylphenol.
4). The content of (c) is 0.5 to 5.0% by mass based on the total mass of the composition, and
4. The grease composition according to any one of 1 to 3, wherein the content of (d) is 0.5 to 5.0% by mass based on the total mass of the composition.
5. (c) is selected from the group consisting of p, p'-dioctyldiphenylamine, N-phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine and mixtures of two or more thereof, and the content of (c) The grease composition as described in 1 above, wherein 0.5 to 5.0% by mass based on the total mass of the composition.
6). (d) is 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), benzenepropanoic acid, 3 , 5-bis (1,1-dimethyl-ethyl) -4-hydroxy C7-C9 side chain alkyl ester, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and two of these 6. The grease composition according to 1 or 5, wherein the grease composition is selected from the group consisting of a mixture of at least seeds, and the content of (d) is 0.5 to 5.0% by mass based on the total mass of the composition.
7). The bearing which enclosed the grease composition of any one of said 1-6.

  ADVANTAGE OF THE INVENTION According to this invention, compared with the grease composition for main motor bearings of the conventional railway vehicle, the grease composition for main motor bearings of the railway vehicle which is excellent in heat resistance and has a long bearing lubrication life can be provided.

(A) Thickener The thickener used in the present invention is generally called a lithium complex, and has a feature that it is excellent in heat resistance as compared with lithium soap.
The hydroxy fatty acid having 12 to 24 carbon atoms constituting the thickener of the present invention is most preferably 12-hydroxystearic acid. Others include 12-hydroxylauric acid, 16-hydroxypalmitic acid and the like.
As the aliphatic dicarboxylic acid having 2 to 12 carbon atoms constituting the thickener of the present invention, azelaic acid is most preferable. Others include sebacic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, peric acid, undecanedioic acid, dodecanedioic acid and the like.
The thickener used in the present invention is particularly preferably a lithium complex of 12-hydroxystearic acid and azelaic acid.
The ratio of the aliphatic dicarboxylic acid having 2 to 12 carbon atoms in the total amount of the hydroxy fatty acid having 12 to 24 carbon atoms and the aliphatic dicarboxylic acid having 2 to 12 carbon atoms used in the present invention is 20 to 40% by mass. Is preferred. If it is less than 20% by mass or exceeds 40% by mass, it is difficult to obtain a thermally stable thickener, and it may not be suitable as a grease for a main motor bearing of a railway vehicle rotating at high temperature and high speed.
The blending amount of the thickener in the composition of the present invention is preferably 5 to 25% by mass. If it is less than 5% by mass, the resulting grease may be fluid, and if it exceeds 25% by mass, it may solidify. More preferably, it is 8-20 mass%.
Urea-based thickeners generally have better heat resistance than lithium complexes, but they are less fluid than lithium complexes for lubrication of cylindrical roller bearings and provide a sufficient lubrication life. Absent.

(B) a base oil for use in base oils present invention, 40 ° C. and an oil having kinematic viscosity of 300 to 500 mm ² / s of the 40 ° C. oil kinematic viscosity of 80~300mm ² / s, and 40 ° C. dynamic viscosity containing an oil of 20 to 80 mm ² / s, and a kinematic viscosity at 40 ° C. is 80~200mm ² / s.
The kinematic viscosity at 40 ° C. of the base oil used in the present invention needs to be 80 to ²⁰⁰ mm ² / s, and preferably 100 to 150 mm ² / s. If it is less than 80 mm ² / s, evaporation loss is high at high temperatures, and grease may solidify early. If it exceeds 200 mm ² / s, problems may arise in startability at low temperatures.
The proportion of oil having a kinematic viscosity at 40 ° C. of 20 to 80 mm ² / s in the base oil is preferably 20 to 50% by mass. If the amount is less than 20% by mass, the temperature rise of the bearing may increase. If the amount exceeds 50% by mass, the amount of evaporation decreases at high temperatures, and the grease may solidify early.
As the base oil used in the present invention, mineral oil, synthetic oil or a mixture thereof can be used. Synthetic oils include ether oils typified by alkyl diphenyl ethers, synthetic hydrocarbon oils typified by polyalphaolefins, and ester-based synthetic oils typified by diesters and tetraesters. As the mineral oil, paraffinic (P-based) mineral oil is more preferable.

Additives The present invention comprises (c) an amine-based antioxidant and (d) a hindered phenol-based antioxidant as essential components.
(c) The amine-based antioxidant is preferably selected from the group consisting of p, p′-dioctyldiphenylamine, N-phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, and mixtures thereof.
It is preferable that the compounding quantity of the amine antioxidant in the composition of this invention is 0.5-5.0 mass%. If it is less than 0.5% by mass, the effect is low, and if it exceeds 5.0% by mass, the effect reaches its peak.

(d) The hindered phenol antioxidant is 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate ), Benzenepropanoic acid, 3,5-bis (1,1-dimethyl-ethyl) -4-hydroxy C7-C9 side chain alkyl ester, octadecyl-3- (3,5-di-t-butyl-4-hydroxy Preferably, it is selected from the group consisting of (phenyl) propionate and mixtures thereof.
It is preferable that the compounding quantity of the hindered phenolic antioxidant in the composition of this invention is 0.5-5.0 mass%. If it is less than 0.5% by mass, the effect is low, and if it exceeds 5.0% by mass, the effect reaches its peak.

[Optional additives]
In addition, any additives usually blended in grease can be used as necessary. Specific examples include rust inhibitors, metal corrosion inhibitors, oiliness agents, antiwear agents, extreme pressure agents, and solid lubricants.

[Mixing consistency]
The penetration of the grease composition of the present invention is preferably 200 to 400, more preferably 250 to 350. Leakage tends to occur when the penetration level exceeds 400. On the other hand, when the penetration is less than 200, the stirring resistance increases.

  The bearing that encloses the grease composition of the present invention is a bearing used in a railway vehicle main motor. The main motor is preferably a fully closed type. As the bearing, a rolling bearing, particularly a roller bearing, particularly a cylindrical roller bearing is suitable. The material of the bearing is not particularly limited, but is preferably copper.

<Test grease>
The contents of the test grease are shown in Tables 1 and 2.
The thickener is a lithium complex consisting of a lithium salt of 12 hydroxystearic acid and azelaic acid.
Three types of base oils, mineral oils A, B, and C (all P-based mineral oils) were used and mixed at a ratio (mass%) shown in the table. The kinematic viscosity at 40 ° C of each base oil is as follows.
Mineral oil A: 414mm ² / s mineral oil B: 101 mm ² / s mineral oil C: 39.5mm ² / s
As additives, p, p'-dioctyldiphenylamine was used as an amine-based antioxidant, and 2,6-di-tert-butyl-4-methylphenol was used as a phenol-based antioxidant.

(Preparation of grease composition)
In 426.2 g of base oil, 127.5 g of 12-hydroxystearic acid was added and heated to a temperature (80 to 90 ° C.) at which a completely transparent liquid state was obtained. To this, add 19.5 g of lithium hydroxide monohydrate to 100 g of water in advance and dissolve by heating. Then, saponification of 12-hydroxystearic acid is performed with vigorous stirring to form lithium salt of 12-hydroxystearic acid. did.
Next, 42.5 g of azelaic acid was added and stirring was continued until a uniform state was achieved. A solution prepared by adding 19.5 g of lithium hydroxide monohydrate to 100 g of water and dissolving it by heating was added thereto, and saponification reaction of azelaic acid was performed with vigorous stirring. After about 60 minutes, it was confirmed by infrared spectroscopy that no unreacted fatty acid was absorbed, and the saponification reaction was terminated.
Next, the heating process was started and the contents were gradually heated to 200 ° C. When the temperature reached 200 ° C., 364.8 g of the remaining base oil was added, and the mixture was cooled to room temperature as it was, and passed through a three-stage roll once to obtain a base grease. The final content was 1000 g.
In accordance with Tables 1 and 2, an antioxidant and a base oil were added to the above base grease, and a three-stage roll was passed twice to obtain grease compositions of Examples 1 to 8 and Comparative Examples 1 to 6.

<Test method>
・ Consistency (JIS K 2220 7)
・ Drip point (JIS K 2220 8)
・ Bearing lubrication life test The bearing life was defined as the time when the bearing was rotated under the conditions described below and the bearing temperature reached 110 ° C.
[Test conditions]
Bearing: NU214
Load: Radial load: 250kgf
Number of revolutions: 8200rpm
Grease filling amount: 5.6 g
Temperature: 120 ℃ control

・ Bearing temperature rise test Rotate the bearing under the conditions described below and record the maximum temperature of the outer ring during operation.
[Test conditions]
Bearing: NF 306
Radial load: 25 lbs
Thrust load: 40 lbs
Rotation speed: 3500rpm
Grease filling amount: 20 g
Test time: 3 hours

  Examples 1-8, which use a three-component base oil and use an amine-based antioxidant and a phenol-based antioxidant in combination, can suppress the temperature rise of the bearing and have a bearing lubrication life of 1000 hours or more. Improvement is recognized compared to.

Claims (6)

(a) a thickener comprising a lithium salt of a C12-24 hydroxy fatty acid having one or more hydroxyl groups and a C2-12 fatty acid dicarboxylic acid;
(b) and 40 ° C. oil kinematic viscosity of 300 to 500 mm ² / s of the 40 ° C. oil kinematic viscosity of 80~300mm ² / s, the kinematic viscosity of 40 ° C. and the oil 20 to 80 mm ² / s A base oil having a kinematic viscosity at 40 ° C. of 80 to 200 mm ² / s,
(c) an amine-based antioxidant, and
(d) A grease composition for a main motor bearing of a railway vehicle containing a hindered phenol-based antioxidant ,
(c) is selected from the group consisting of p, p'-dioctyldiphenylamine, N-phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine and mixtures of two or more thereof;
(d) is 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), benzenepropanoic acid, 3 , 5-bis (1,1-dimethyl-ethyl) -4-hydroxy C7-C9 side chain alkyl ester, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and two of these Selected from the group consisting of mixtures of more than species,
The grease composition . (c) is p, p'-dioctyldiphenylamine, and
(d) is 2, 6-di -tert- butyl-4-methylphenol, claim 1 grease composition. The content of (c) is 0.5 to 5.0% by mass based on the total mass of the composition, and
The grease composition according to claim 1 or 2 , wherein the content of (d) is 0.5 to 5.0 mass% based on the total mass of the composition. a) a thickener comprising a lithium salt of a hydroxy fatty acid having 12 to 24 carbon atoms having one or more hydroxyl groups and a fatty acid dicarboxylic acid having 2 to 12 carbon atoms ,
(b) and 40 ° C. oil kinematic viscosity of 300 to 500 mm ² / s of the 40 ° C. oil kinematic viscosity of 80~300mm ² / s, the kinematic viscosity of 40 ° C. and the oil 20 to 80 mm ² / s A base oil having a kinematic viscosity at 40 ° C. of 80 to 200 mm ² / s ,
( c) an amine-based antioxidant, and
( d) Hindered phenolic antioxidant
A grease composition for a main motor bearing of a railway vehicle containing
(c) is selected from the group consisting of p, p'-dioctyldiphenylamine, N-phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine and mixtures of two or more thereof, and the content of (c) Wherein the grease composition is 0.5 to 5.0% by mass, based on the total mass of the composition. (d) is 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), benzenepropanoic acid, 3 , 5-bis (1,1-dimethyl-ethyl) -4-hydroxy C7-C9 side chain alkyl ester, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and two of these The grease composition according to claim 4 , wherein the grease composition is selected from the group consisting of a mixture of at least seeds, and the content of (d) is 0.5 to 5.0 mass% based on the total mass of the composition. The bearing which enclosed the grease composition of any one of Claims 1-5 .