JP2015074659A - Lubricant composition for propeller shaft sliding yoke mechanism, propeller shaft sliding yoke mechanism, and lubrication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil solution which, when assembling a propeller shaft sliding yoke part, is a semisolid making it easy to perform lubrication work by coating, and which, in a temperature environment of actual operation, becomes liquid and penetrates into a narrow space between the sliding parts to reduce frictional wear thereof, and to provide an application method of the oil solution.SOLUTION: Provided is a lubricant composition for a propeller shaft yoke part, comprising: a mineral oil-based lubricant base oil having a kinematic viscosity at 40°C of 10 to 1000 mm/s; a fatty acid monoamide compound represented by the following general formula (1) having a melting point of 40 to 60°C in an amount of 10 to 30 mass% based on the total amount of the lubricant composition; and a lubrication improver which reduces frictional wear in an amount of 0.01 to 20 mass% based on the total amount of the lubricant composition: R-NH-C(=O)-R(1) [in the formula (1), Rand Rrepresent an aliphatic hydrocarbon group and/or hydrogen, and have a total of 20 to 40 carbon atoms].

Description

  The present invention relates to a lubricating oil composition for a propeller shaft slide yoke mechanism, a propeller shaft slide yoke mechanism, and a lubrication method.

  The propeller shaft that transmits the engine power of the car to the front and rear wheels rotates at a high speed and must follow the change in the length between the front and rear wheels due to the inertial force at the time of departure and stop, and has a slide mechanism A yoke lubrication system is adopted.

  Grease is an oil agent in which a fibrous thickener such as a metal soap or a urea compound is dispersed in a liquid lubricating oil to form a semi-solid. Since it is semi-solid, it has the merit that it is difficult for oil to leak and the lubrication system can be simplified and miniaturized, and it is widely used for bearings and the like (Non-Patent Document 1). Major applications include transport equipment such as automobiles and railways, information equipment such as computers, steel equipment such as rolling mills, and industrial machines such as machine tools and construction machines. In addition to the base oil and the thickener, various additives are added to the grease in order to impart lubricity, oxidation stability, and rust prevention, and are formulated according to the application. In addition, once the grease is semi-solid, the base oil and the thickener component are separated even when heated, and does not exhibit thermoreversibility of the liquid and semi-solid state change.

  On the other hand, amide-based gel lubricants that are blended with fatty acid amides in liquid lubricant, heated and dissolved, and then cooled to a semi-solid form are lubricants that can be reversibly and reversibly liquid and semi-solid. is there. Porous metal sintered oil-impregnated bearings and the like are known as applications utilizing the thermoreversible state change (Patent Documents 1 and 2).

  In the above-described automobile propeller shaft slide yoke mechanism, grease is usually used in order to reduce slide resistance and prevent seizure and abnormal wear. For example, a grease composition containing a base oil, a thickener having a dropping point of 240 ° C. or higher, a viscosity index improver, and a nickel dithiocarbamate, zinc dithiocarbamate, and a phosphorus additive as a lubricity improver. Known (Patent Document 3).

WO2006 / 051671 WO2007 / 116642 JP 2003-55680 A

Lubricating grease basics and applications, Japan Tribology Society Grease Study Group, Yokendo, February 5, 2007, 4th page

  However, when semi-solid grease is used for the propeller shaft slide yoke lubrication part, the grease is unevenly distributed at the end of the reciprocatingly sliding yoke sliding part, and the sliding part is an oil agent. There was a problem that was in shortage.

  The present invention solves the above-mentioned problem, and when assembling the propeller shaft slide yoke part, it is semi-solid and easy to lubricate by coating, becomes liquid in the temperature environment in actual operation, and becomes a narrow gap in the sliding part. It is an object of the present invention to provide an oil agent that easily penetrates and reduces frictional wear of a sliding portion, and a method of using the same.

  As a result of diligent research to solve the above problems, the present inventor has mixed a base oil with a predetermined amount of a fatty acid amide compound having a melting point of 40 to 60 ° C. and a specific lubricity improving additive at room temperature. In the assembly operation, the lubricant composition can be applied in a semi-solid state, and it becomes liquid in the actual use environment of the propeller shaft slide yoke part, and friction wear can be greatly reduced compared to conventional grease lubrication. I found. Furthermore, it has been found that by providing a propeller shaft slide yoke portion using this lubricating composition with a sealing mechanism, the liquefied oil agent can be prevented from scattering and disappearing, and the performance can be maintained over a long period of time.

That is, the present invention is as follows.
[1] A lubricating composition comprising a mineral oil-based lubricating base oil having a kinematic viscosity at 40 ° C. of 10 to 1000 mm ² / s and a melting point of 40 to 60 ° C. and a fatty acid monoamide compound represented by the following general formula (1) A lubricating composition for a propeller shaft yoke part, containing 10 to 30% by mass on the basis of the total amount and 0.01 to 20% by mass of a lubricity improver for reducing frictional wear on the basis of the total amount of the lubricating composition.
R ¹ —NH—C (═O) —R ² (1)
[R ¹ and R ² in the general formula (1) are an aliphatic hydrocarbon group and / or hydrogen, and the total number of carbon atoms is 20 to 40. ]
[2] The lubricating composition for a propeller shaft yoke according to [1], wherein the total carbon number of R ¹ and R ^{2 in} the general formula (1) is 24 to 32.
[3] The lubricating composition for a propeller shaft yoke according to [1], wherein the lubricity improver that reduces frictional wear is an oil-soluble organic molybdenum compound.
[4] The lubricating composition for a propeller shaft yoke according to [1], wherein the lubricity improver for reducing frictional wear is at least one selected from molybdenum dithiocarbamate and molybdenum dithiophosphate.
[5] A propeller shaft yoke portion including the lubricating composition according to any one of [1] to [4], and having a seal mechanism that prevents leakage of the liquefied lubricating composition to the outside.
[6] A method for lubricating a propeller shaft yoke part, wherein the lubricating composition according to any one of [1] to [4] is in a liquid state and is present in a sliding part of the propeller shaft yoke part.
[7] The lubricating composition according to any one of [1] to [4] is introduced into the propeller shaft yoke in a semi-solid state, and the propeller shaft yoke is slid in a liquid state when the propeller shaft yoke is operated. Lubricating method for propeller shaft yoke to be present in the part.

  Since the lubricating composition of the present invention is semi-solid at room temperature, it can be easily applied to the propeller shaft slide yoke, and since it becomes liquid at the operating temperature of the slide yoke, it is easy to intervene in the slide. Even when used for a long period of time, the lubricant is less likely to be unevenly distributed at the end of the yoke sliding portion, so that the sliding portion will not be in a state of insufficient oil, and frictional wear can be suppressed over a long period of time, resulting in static friction / dynamic friction. It is possible to suppress the occurrence of stick-slip due to the high ratio and to reduce the occurrence of crank shock.

FIG. 1 is a conceptual diagram showing the position of a propeller shaft in an automobile. FIG. 2 is a conceptual diagram of the propeller shaft.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The lubricating composition of the present invention contains a mineral-based lubricating base oil, a fatty acid monoamide compound having a melting point of 40 to 60 ° C., and a lubricity improving additive that reduces frictional wear.

Mineral lubricating base oil used in the present invention, in order to have excellent lubricity, kinematic viscosity at 40 ° C. is intended 10 to 1000 mm ² / s, preferably from 50 to 500 mm ² / s. The kinematic viscosity at 40 ° C. is measured at 40 ° C. by the method defined in JIS K 2283.
Mineral oil-based lubricating base oil is a lubricating oil fraction obtained by purifying distillate obtained by subjecting crude oil to atmospheric distillation or further distillation under reduced pressure by a purification process such as hydrorefining, solvent extraction, solvent dewaxing, It is also possible to use a mixture of two or more refined oils having different properties obtained by different crude oils or distillate oils by different process combinations and sequences.
The content of this mineral oil-based lubricating base oil is the balance in which the fatty acid monoamide compound and the lubricity improver are blended, but is preferably 30 to 90% by mass, more preferably 70 to 90% by mass, based on the total amount of the lubricating composition. preferable. When the content of the lubricating base oil is out of the range of 30 to 90% by mass, it becomes difficult to easily prepare a composition having a desired hardness, and the oiling operation becomes difficult, which is not preferable.

  The fatty acid monoamide compound exhibits a semi-solid state at the lubrication temperature (10 to 20 ° C.) when assembling the propeller shaft slide yoke parts, and the sliding portion temperature (40 to 100 ° C.) of the propeller shaft slide yoke in actual operation of the automobile. The fatty acid monoamide of the following general formula (1), which is a fatty acid monoamide compound having a single amide group in the molecular structure, has a melting point of 40 to 60 ° C. so that it becomes liquid.

R ¹ —NH—C (═O) —R ² (1)
(Here, R ¹ and R ² are an aliphatic hydrocarbon group and / or hydrogen, and the total number of carbon atoms is 20 to 40.)

In the above formula (1), in order for the melting point to be in the desired range of 40 to 60 ° C., the total carbon number of R ¹ and R ² is 20 to 40, preferably 24 to 32, and the aliphatic hydrocarbon group is In view of oxidation stability, a saturated hydrocarbon group is preferable.

Preferred fatty acid monoamide compounds include eicosyl amide, triacosyl amide, tetracosyl amide, octaeicosanoic acid amide, decyl decanoic acid amide, decyl eicosanoic acid amide, octadecyl octadecanoic acid amide and the like.
In addition, if melting | fusing point is 40-60 degreeC, it is also possible to mix | blend multiple types of the said fatty acid monoamide.
The fatty acid monoamide compound having a melting point of 40 to 60 ° C. is blended in an amount of 10 to 30% by mass, preferably 15 to 25% by mass, based on the total amount of the lubricating composition. When the content of the fatty acid monoamide compound having a melting point of 40 to 60 ° C. is out of the range of 10 to 30% by mass, it becomes difficult to easily prepare a composition having a desired hardness, and oiling work becomes difficult.

  The lubricity improver that reduces frictional wear prevents wear and seizure between sliding surfaces when excessive load is applied to the sliding surface of the propeller shaft slide yoke, and maintains good friction characteristics. In order to maintain the desired slide performance over a long period of time, it is an additive that can form a strong lubricating film on the surface of the sliding part, and is a commonly used antiwear agent, extreme pressure agent, oily An agent, a friction modifier and the like can be appropriately blended.

As a lubricity improver, a molybdenum-containing compound, preferably an oil-soluble organic molybdenum, in particular molybdenum dithiocarbamate and / or molybdenum dithiophosphate, is used to improve extreme pressure while reducing friction and wear. It is preferable to mix | blend 1 or more types of these.
Organic molybdenum, in particular molybdenum dithiocarbamate and molybdenum dithiophosphate, is known to form a molybdenum disulfide film with low friction and high extreme pressure performance on the sliding surface, and the melting point of the present invention is 40-60 ° C. In the case of a composition, even in a harsh lubricating environment, it becomes liquid unlike grease, so it is easy to maintain an oil film on the sliding part, and the oil-soluble organic molybdenum in the oil is effectively applied to the surface of the sliding part. It is possible to form a lubricating coating.

  A lubricity improver may be used individually by 1 type, or may be used in combination of 2 or more type. The content of the lubricity improver may be as long as desired lubricity is obtained. For example, it is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, based on the total amount of the lubricating composition. It is. If it is 0.01% by mass or less, sufficient lubricity will not be exhibited, and if it exceeds 20% by mass, the stability will be lowered and the cost will be increased.

In addition to the above components, the lubricating composition according to the present embodiment is generally used in lubricating oils and greases as necessary. For example, detergents, dispersants, antiwear agents, viscosity index improvers, and antioxidants An agent, extreme pressure agent, rust inhibitor, corrosion inhibitor and the like can be added as appropriate.
However, a metal soap system that exhibits a semi-solid state at an oiling operation temperature (10 to 20 ° C.) and inhibits liquid formation at a sliding portion temperature (40 to 100 ° C.) of a propeller shaft slide yoke in actual operation of an automobile. Urea thickeners should not be added.

  The method for producing a lubricating composition according to this embodiment comprises mixing a predetermined amount of a lubricating base oil component, a fatty acid monoamide compound component having a melting point of 40-60 ° C., and a lubricity improver component, and heating with stirring. Then, after each component is uniformly dissolved, a step of obtaining a semi-solid lubricating composition by gradually cooling to room temperature is provided. In this case, the content of the fatty acid amide is 10 to 30% by mass, the content of the lubricity improver component is 0.01 to 20% by mass, and the content of the lubricating base oil component is the remainder, preferably 30 to 90% by mass. It is recommended to select appropriately within the range.

In this embodiment, the fatty acid amide may be mixed with the previously prepared lubricant base oil and the lubricity improver component, and stirred and heated to be uniformly dissolved, or alternatively, the previously prepared lubricant base oil and A semi-solid composition comprising a fatty acid amide may be mixed with a lubricity improver component to make it uniform, and a mixture of a pre-prepared fatty acid amide and a lubricity improver component may be mixed with a lubricating base oil component. It may be diluted. Furthermore, fatty acid amides may be obtained by blending fatty acid amide raw materials and reacting them in a base oil.
In addition, a lubricating composition obtained by mixing a lubricating base oil component, a fatty acid monoamide compound component, and a lubricity improver component can be subjected to pressure dispersion treatment with a roller or a mill as necessary. .

The propeller shaft using the lubricating composition of the present invention is a mechanism for transmitting the engine power of the automobile to the front wheels and the rear wheels. The propeller shaft rotates at a high speed, and the length between the front wheels and the rear wheels according to the inertial force at the time of starting and stopping. The yoke lubrication system having a slide mechanism is employed (FIG. 1).
Moreover, it is possible to suppress the leakage and outflow of the liquefied lubricating oil agent by clamping with the male spline / female spline with the part as a boot structure.

  As a method for lubricating the propeller shaft slide yoke lubrication part, it is preferable to use a lubricating composition that is semi-solid at room temperature and liquid in a temperature environment (0 to 100 ° C.) in actual operation. Specifically, when assembling components at room temperature, in order to easily apply the required amount of oil to the sliding part, using a semi-solid lubricating composition having an appropriate hardness, as an application method A spatula, a brush, a grease gun or the like is preferable, and an automatic greasing apparatus using an electric pump can also be used. In order to prevent the lubricating composition liquefied in actual operation from scattering and disappearing outside the propeller shaft slide yoke mechanism, the propeller shaft slide yoke mechanism is equipped with the above-mentioned sealing mechanism as a countermeasure against oil leakage for a longer period of time. Excellent performance can be maintained.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Mineral oil base oil]
A mineral oil-based lubricating base oil having the following properties, obtained by subjecting a distillate obtained by distilling the atmospheric distillation residue under reduced pressure to a solvent, was used.
Kinematic viscosity at 40 ° C .: 180 mm ² / s
Density at 15 ° C .: 0.89 g / cm ³
Viscosity index: 95
Pour point: -15.0 ° C
Flash point: 270 ° C

[Fatty acid amide A]
As the fatty acid amide, a monoamide having a melting point of 48 ° C., in which R ¹ and R ^{2 in} the above formula (1) are saturated hydrocarbon groups and has a total number of hydrocarbons of 28, was used.
[Fatty acid amide B]
As the fatty acid amide, ethylene bis stearic acid amide having a melting point of 145 ° C. was used.

[Lubricity improver A]
As the lubricity improver A, oil-soluble molybdenum dithiocarbamate was used.
[Lubricity improver B]
Oil-soluble molybdenum dithiophosphate was used as a lubricity improver.

[Example 1, Comparative Examples 1 and 2]
In Example 1, a mineral oil-based lubricating base oil was put in a stainless steel container in the amount shown in Table 1 (indicated by mass%). Furthermore, fatty acid amide compound A, lubricity improver A, and lubricity improver B were added to the lubricating base oil in the container, heated to 100 ° C., stirred with a magnetic stirrer, and uniformly dissolved. After cooling to room temperature, the base oil was made semi-solid with fatty acid amide. This was subjected to pressure dispersion treatment with a roller (three rolls) to obtain a lubricating composition having the composition shown in Table 1. Moreover, lithium soap grease (mineral oil lubricant base oil, using 40 ° C. kinematic viscosity 180 mm ² / s) was used as a comparative grease of the prior art. Comparative Example 2 was prepared in the same manner as in Example 1, but was dissolved in the base oil at a temperature equal to or higher than the melting point of fatty acid amide B (heating temperature 150 ° C.).

[Evaluation test]
Using the lubricating compositions of Example 1 and Comparative Examples 1 and 2, the Falex lubricity test and the propeller shaft slide yoke actual machine evaluation were performed by the following methods.
[Consistency]
A consistency test was performed on the hardness of the semisolid lubricating composition by the method defined in JIS K2220.
[Drip point]
The temperature (melting point) at which the lubricating composition changed from a semi-solid state to a liquid state was measured by the dropping point evaluation method of JIS K2220. In the case of grease, the temperature at which oil begins to drip from the grease composition is expressed as the dropping point.

[Falex lubricity test]
Evaluation of wear resistance using a pin / V block type rotary Falex tester, which is a line contact wear test, to evaluate the lubricity on a desk simulating the lubrication environment (low speed, high load) of a propeller shaft slide yoke did. The material of the pin and the V-shaped block is SUJ-2. The test conditions were as follows: the pin rotation speed was 60 rpm, the sliding speed was 2 cm / s, the load was 2224 N, 25 ° C., and 70 ° C. for 240 minutes. In addition, about 0.2g of the test oil is first applied to the V-shaped part of the block, the rotating pin is sandwiched between the two V-shaped blocks and assembled to the testing device, and the load is applied across the pin from the block side. The pin was rotated at a constant speed and the wear test was started. If the wear test is conducted for 240 minutes, and there is no seizure or abnormal wear, the pin after the test is washed with an organic solvent and dried, and then the weight is measured. Calculated. In addition, the amount of wear in the middle of 120 minutes was measured and recorded.

[Evaluation of actual propeller shaft slide yoke]
Example 1 (gel-like lubricant of the present invention), propeller shaft having a spline structure in the shaft shaft (FIG. 1), Comparative Example 1 (conventional grease using lithium soap as a thickener, conventional technology) ) And Comparative Example 2 (a gel-like lubricant having a high melting point) were used to confirm the effect in the actual machine of the present invention.
When a spline catching phenomenon occurs in a spline sliding portion provided in the propeller shaft, a vehicle shock occurs (hereinafter referred to as a crank shock). This crank shock can be evaluated by the static slide resistance value and its speed dependency. In other words, regarding the speed dependency, the difference between the slide resistance (static slide resistance) in the low speed range and the slide resistance (dynamic slide resistance) in the medium to high speed range (static slide resistance-dynamic slide resistance) is reduced. Crank shocks are less likely to occur, and crank shocks are more likely to occur as the difference increases.
In the evaluation procedure, the crank shock performance evaluation (static slide resistance measurement, dynamic slide resistance measurement) is performed in the initial stage, the endurance test is performed, and after the endurance test, the crank shock performance is evaluated again (static slide resistance measurement, dynamic slide resistance measurement). Went. An outline of the evaluation conditions is shown below.
[1] Crank shock performance evaluation and static slide resistance measurement Torque is applied to the peller shaft that rotates under a temperature environment of 50 ° C, and the spline part is swung at a low speed in a specific pattern to measure the axial slide resistance. .
・ Dynamic slide resistance measurement Torque is applied to the peller shaft that rotates under a temperature environment of 50 ° C, and the spline part is swung at a medium to high speed in a specific pattern to measure the slide resistance in the axial direction.
[2] Durability test Torque is applied to the peller shaft rotating under a temperature environment of 50 ° C., and the spline part is swung at a high speed a specific number of times in a specific pattern.

The lithium grease of the prior art (Comparative Example 1) has a hardness corresponding to No. 1 in consistency classification. In the Falex wear test simulating the lubrication environment of the propeller shaft slide yoke, the amount of wear exceeded 20 mg after a test time of 120 hours under the conditions of 25 ° C. and 70 ° C., and seizure occurred in the time up to 240 hours. The gel lubricant (Comparative Example 2) in which organic molybdenum and a fatty acid amide having a melting point of 145 ° C. were blended into the base oil was not seized under both conditions of 25 ° C. and 70 ° C. in the Falex wear test, but 240 hr. The amount of wear exceeded 20 mg. On the other hand, Example 1 prepared by blending organic molybdenum and fatty acid monoamide in the base oil and adjusted to a melting point of 48 ° C. has the same consistency classification No. 1 as that of Comparative Example 1, and is similar to conventional grease in sliding parts. Can be applied. Furthermore, in the Falex wear test, the wear amount at 240 hrs was 10 mg or less under both conditions of 25 ° C. and 70 ° C., indicating excellent wear resistance.
In addition, the results of the actual machine evaluation are indicated by an index using the static slide initial measurement data of the present invention (Example 1) as a reference (= 1). Moreover, the sliding speed at the time of moving slide measurement was changed stepwise, and the data was arranged based on the sliding speed of 5 mm / s. The following results were obtained in the actual machine evaluation.
-Static slide resistance falls by this invention (Example 1) compared with a prior art (comparative example 1).
In the prior art (Comparative Example 1), the dynamic slide resistance decreases after endurance and crank shock is likely to occur. However, in the present invention (Example 1), a phenomenon that the dynamic slide resistance alone decreases is not observed.
Further, when the wear amount of the male spline after the durability test was compared, when the wear amount after the durability of the prior art (Comparative Example 1) was used as a reference (= 1), the data was shown as an index, and the present invention (Example 1) ) Shows that the wear of the male spline is greatly reduced. This high wear resistance is considered to be a mechanism that suppresses the formation of an oil film, prevents a decrease in dynamic slide resistance after durability, and exhibits good crank shock properties.
Also, in this actual machine evaluation, the lubrication sliding part is used as a boot structure and clamping with a male spline / female spline is used to suppress the occurrence of leakage of the liquefied lubricating oil composition. It was confirmed that the occurrence can be prevented.

  The lubricating composition of the present invention can be easily applied to the sliding portion in the assembly operation of the propeller shaft slide yoke, and in the actual operation, it reduces the frictional wear and suppresses the occurrence of crank shock. There is an effect. Therefore, the lubricating composition of the present invention can be suitably used for propeller shaft slide yoke lubrication, and is useful in transportation machinery systems.

1 Propeller shaft 2 Spline sliding part

Claims (7)

A mineral oil-based lubricating base oil having a kinematic viscosity at 40 ° C. of 10 to 1000 mm ² / s, a melting point of 40 to 60 ° C., and a fatty acid monoamide compound represented by the following general formula (1) based on the total amount of the lubricating composition: 10 to 30 A lubricating composition for a propeller shaft yoke, comprising 0.01% by mass to 20% by mass of a lubricity improver that reduces frictional wear by mass% based on the total amount of the lubricating composition.
R ¹ —NH—C (═O) —R ² (1)
[In said formula (1), R < ¹ > and R < ² > is an aliphatic hydrocarbon group and / or hydrogen, and the sum total of the carbon number is 20-40. ] The lubricating composition for propeller shaft yokes according to claim 1, wherein the total number of carbon atoms of R ¹ and R ^{2 in} the general formula (1) is 24 to 32.   The lubricating composition for a propeller shaft yoke according to claim 1, wherein the lubricity improver for reducing frictional wear is an oil-soluble organic molybdenum compound.   The lubricating composition for a propeller shaft yoke according to claim 1, wherein the lubricity improver for reducing frictional wear is at least one selected from molybdenum dithiocarbamate and molybdenum dithiophosphate. The lubricating composition according to any one of claims 1 to 4,
A propeller shaft yoke having a seal mechanism for preventing leakage of the liquefied lubricating composition to the outside.   A method for lubricating a propeller shaft yoke part, wherein the lubricating composition according to any one of claims 1 to 4 is in a liquid state and is present in a sliding part of the propeller shaft yoke part.   5. A propeller in which the lubricating composition according to any one of claims 1 to 4 is introduced into a propeller shaft yoke portion in a semi-solid state, and is present in a sliding state of the propeller shaft yoke portion as a liquid state during operation of the propeller shaft yoke portion. Lubricating method for shaft yoke.

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