JP2002080878A - Lubricating grease for constant velocity joint, and constant velocity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating grease for a constant velocity joint, which can reduce the resistance to sliding in the axial direction of a constant velocity joint and which hardly causes the vibration of a plunging type constant velocity joint in particular in use, and a plunging type constant velocity joint for an automobile, which hardly suffers vibration in use. SOLUTION: The lubricating grease enclosed in the inside of a plunging type constant velocity joint for an automobile is a lubricating grease made by blending a base oil with a urea-base thickening agent, containing 0.1-10 wt.% of at least one organocopper compound selected from copper stearate, copper naphthenate, and copper dithiocarbamate, and mixed with an extreme- pressure additive comprising an organomolybdenum compound and/or an organozinc compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lubricating grease for a constant velocity joint and a plunging type constant velocity joint for an automobile.

[0002]

2. Description of the Related Art As typical examples of plunging type constant velocity joints, there are a double offset type constant velocity joint and a tripod type constant velocity joint. As shown in FIG. 1, the double offset type constant velocity joint has six track grooves 3 and 4 in the axial direction formed at equal angles on the inner surface of the outer ring 1 and the outer surface of the spherical inner ring 2, and its track Grooves 3, 4
The ball 5 inserted between the cages 6 is supported by a cage 6, the outer periphery of the cage 6 is a spherical surface 7, and the inner periphery is a spherical surface 8 adapted to the outer periphery of the inner ring 2, which rotates around the outer ring axis A. The shaft and the shaft that follows and rotates around the shaft axis B are connected via the ball 5 so as to rotate at a constant speed.

[0003] The double offset type constant velocity joint has six balls when transmitting the rotational torque in a state with an operating angle (ie, a state in which the outer ring axis A and the shaft axis B intersect at an appropriate angle). The plane on which 5 rotates is not orthogonal to the axis A, but is inclined.

When the relative position of the ball 5 with respect to the track groove 3 is viewed in this state, the more the shaft axis B intersects the outer ring axis A at a larger angle, the more the ball rotation surface C is inclined. 1 makes one reciprocation along the track grooves 3 and 4 in the direction of the arrow in FIG.

Since the moving ball 5 is held by the cage 6 so as not to move along the groove direction in the track grooves 3 and 4, it is difficult for the ball 5 to roll in the groove direction. In addition, it reciprocates mainly by sliding.

Next, the relationship between the operating angle and the sliding surface of the ball 5 in the plunging constant velocity joint for an automobile will be described. When the vehicle starts to start or accelerates, the vehicle body floats, and the vehicle body shakes due to road surface running conditions and the like. In this case, the operating angle of the plunging type constant velocity joint changes by increasing or decreasing in the vertical direction, the horizontal direction (front and rear in the drawing), or a combination of these two directions in the drawing. 4 slides while making contact on a new surface different from the previous sliding surface. Thus, the ball 5 and the track groove 3 slide, and a frictional resistance, that is, a force (axial force) acting in the axial direction is generated.

The reciprocating sliding distance of the ball 5 when an axial force is generated fluctuates in accordance with the bending angle of the shaft axis B with respect to the outer ring axis A, that is, the operating angle. For example, when the vehicle suddenly accelerates, the height of the vehicle body changes rapidly, and the operating angle changes abruptly. Therefore, the reciprocating sliding distance of the ball 5 increases and decreases, and the track groove of the ball and the joint outer ring 1 increases. No. 3 comes into contact with a surface (new surface) that has not been in sliding contact until now.

In this case, if a slippery lubricating surface is not immediately formed between the two (the ball and the track groove), the ball transmitting the torque contacts the new surface when sliding in the axial direction of the track groove. At this time, a large axial frictional force (slide resistance) is generated between the ball and the track groove. This becomes the axial force of the joint,
It is considered that this may cause roll of the vehicle body at the time of starting and acceleration, vibration of the vehicle body, or generation of beat sound or muffled sound inside the vehicle at a specific speed.

Conventionally, attempts have been made to solve the above-described vibration generating mechanism by improving the mechanical structure of a constant velocity joint (CVJ).

There is also a need for a technique that can sufficiently suppress the generation of beat sounds or muffled sounds without changing the mechanical structure of the CVJ even in applications other than automobiles.

Incidentally, a lubricating grease to which an organic copper compound is added in order to prevent hydrogen embrittlement caused by intrusion of hydrogen into the steel forming the bearing is disclosed in Japanese Patent Application Laid-Open No. 10-121083. ing.

[0012]

However, the constant velocity joint does not rotate at a high speed unlike the bearing for high-speed rotation disclosed in the publication, and hydrogen embrittlement occurs in a normal use condition. It was considered that there was no advantage, and when the above-mentioned lubricating grease was diverted to a constant velocity joint, other advantages could not be predicted and could not be used for a clear purpose.

In a limited space such as the inside of a car body, it is difficult to improve the structure of the CVJ without increasing the occupied volume of the CVJ. It was difficult to control.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to reduce the sliding resistance in the constant velocity joint, particularly the constant velocity joint, in the axial direction, and to use a constant velocity joint, particularly a plunging type constant velocity joint. An object of the present invention is to provide a lubricating grease for a constant velocity joint which is less likely to cause vibration in a state.

Another object of the present invention is to provide a plunging type constant velocity joint for an automobile which is less likely to cause vibration during use without changing the mechanical structure.

[0016]

According to the present invention, there is provided a lubricating grease sealed in a constant velocity joint, wherein the lubricating grease contains an organic copper-based compound. It is a lubricating grease for constant velocity joints. This lubricating grease preferably contains an organic copper compound in an amount of 0.1 to 10% by weight, and is preferably a lubricating grease containing a base oil and a urea thickener.

As described above, it is known that there is a correlation between the friction coefficient at the time of sliding the axis of the constant velocity joint and the axial force induced thereby (hereinafter referred to as induced thrust force). However, the inventors of the present application examined the performance of various lubricating greases as lubricating greases for constant velocity joints used under lubricating conditions that are liable to wear and generate vibration, and particularly, the induced thrust of actual machines. SRV (Schwingung Reibung u
nd Verschleiss) As a result of measuring the coefficient of friction with a friction and abrasion tester and measuring the induced thrust with a real joint, it was discovered that a material containing an organocopper compound was particularly excellent, and the present invention was completed. Things.

In such a lubricating grease, it is preferable to employ, as the organic copper compound, at least one organic copper compound selected from copper stearate, copper naphthenate and copper dithiocarbamate.

Since the lubricating grease containing the organic copper compound forms a lubricating oil film at a high speed in the constant velocity joint, a new surface without a lubricating oil film does not occur in the constant velocity joint. For example, in a plunging type constant velocity joint for automobiles, a slippery lubricating surface is always formed between a ball and a track groove, and a ball transmitting torque contacts a new surface when sliding in the axial direction of the track groove. No frictional force between ball and track groove (slide resistance)
Rarely occurs. As a result, the axial force of the constant velocity joint is eliminated, so that the vehicle body rolls at the time of starting and accelerating, vibration of the vehicle body, or beat sound or muffled sound in the vehicle at a specific speed is not generated.

In the lubricating grease for a constant velocity joint, it is preferable to add an organic molybdenum compound or an organic zinc compound or an extreme pressure agent used in combination with the lubricating grease.

The lubricating grease for a constant velocity joint containing the above-mentioned extreme pressure agent has more excellent durability than that in which the lubricating grease is sealed, and the axial force of the constant velocity joint is stably maintained for a long period of time. Does not occur, and the vehicle body rolls during starting and acceleration, the vehicle body vibration, or the beat sound or muffled sound in the vehicle at a specific speed is not reliably generated.

Further, when any of the lubricating greases described above is sealed in the plunging type constant velocity joint for an automobile, unnecessary axial force is not generated in the constant velocity joint, and the vehicle body rolls during starting and acceleration, The vibration of the vehicle or the beat sound or muffled sound in the vehicle at a specific speed is not generated.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION As a base oil of a lubricating grease used in the present invention, a mineral oil, an ester-based synthetic oil, an ether-based synthetic oil, a hydrocarbon-based synthetic oil and other known lubricating oils or a mixture thereof are used. can do. Normally, constant velocity joints are covered with rubber boots to prevent intrusion of dust, but mineral oil (paraffinic or naphthenic) is used as a base oil to suppress such boot deterioration. Is preferred.

Examples of the thickening agent used in the present invention include urea compounds such as lithium soap, lithium complex soap, calcium soap, calcium complex soap, aluminum soap, aluminum complex soap, and diurea compounds and polyurea compounds. In order to prepare a lubricating grease having particularly good heat resistance, it is preferable to employ a urea-based thickener.

Examples of the urea thickener include a diurea thickener and a polyurea thickener.

The diurea-based thickener is obtained, for example, in a state of being dispersed in a base oil by a reaction between a diisocyanate and a monoamine. Examples of the diisocyanate include phenylene diisocyanate, diphenyl diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, and hexane diisocyanate. Examples of the monoamine include octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, aniline, p-toluidine, cyclohexylamine and the like.

The polyurea compound is obtained by reacting a diisocyanate with a monoamine or a diamine, and specific examples of the diisocyanate and the monoamine are as described above. In addition, as the diamine, ethylene diamine,
Examples thereof include propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, and xylenediamine.

The organic copper compound used in the present invention is selected from copper stearate ([CH ₃ (CH ₂ ) ₁₆ COO] ₂ Cu), copper naphthenate, and copper dithiocarbamate represented by the following formula (1). Similar effects can be expected with at least one organic copper-based compound, and also with an organic acid salt of copper, an alkoxide of copper, or a chelate compound.

[0029]

[Formula 1]

(In the formula, R ₁ and R ₂ are each an alkyl group, preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms.) The organic molybdenum compound used in the present invention is , Molybdenum dithiocarbamate or molybdenum dithiophosphate. The former is also referred to as molybdenum dialkyldithiocarbamate and represented by the following formula.

[R ¹ R ² N—CS—S] ₂ —Mo ₂ OmSn (wherein R ¹ and R ² are each an alkyl group having 1 to 24 carbon atoms, preferably 3 to 18 carbon atoms, and m + n = 4 And m is 0 to 3 and n is 4 to 1.) The latter molybdenum dithiophosphate is represented by the following chemical formula 2.
It is shown by the formula of.

[0032]

Embedded image

(Wherein R ³ R ⁴ R ⁵ and R ⁶ are each independently a primary or secondary alkyl group having 1 to 24 carbon atoms, preferably 3 to 20 carbon atoms, or 6 to 30 carbon atoms, preferably Represents an aryl group of 8 to 18.) The organic zinc compound used in the present invention is also referred to as a zinc dithiophosphate compound or zinc dithiocarbamate represented by the following formula.

[(R ⁷ O) ₂ -PS-S] ₂ -Zn (wherein R ⁷ is an alkyl group having 1 to 24 carbon atoms or an aryl group having 6 to 30 carbon atoms). The lubricating grease may further contain various additives such as an oil agent, an antioxidant, a rust inhibitor, an extreme pressure agent, an antiwear agent, an anticorrosive, and a polymer.

Preferred examples of the above-described lubricating grease for constant velocity joints and the reasons for limiting the numerical values of the proportions are summarized below. (A) Base oil 45 to 98.9% by weight (b) Urea-based thickener 1 to 25% by weight (c) Organic copper-based compound 0.1 to 10% by weight (d) Organic molybdenum compound 0 to 10% by weight (E) Zinc dithiophosphate compound 0 to 10% by weight The reason that the above mixing ratio is suitable is that if the content of the component (b) is less than 1% by weight, the thickening becomes poor and it becomes difficult to form a grease. This is because the lubricating grease hardens even if it is added in an amount exceeding the weight%, and the desired effect cannot be obtained. If the content of the component (c) is less than 0.1% by weight, it is difficult to sufficiently obtain the desired friction reducing effect. And, if the compounding amount of the components (c), (d) and (e) exceeds 10% by weight, there is no further effect, and the practicality is rather lost.

Taking the above-described reasons for limiting the numerical values into consideration, more preferable compounding ratios are as follows. (A ′) Base oil 65 to 94.5% by weight (b ′) Urea thickener 5 to 20% by weight (c ′) Organocopper compound 0.5 to 5% by weight (d ′) Organic molybdenum compound 0 (E ′) zinc dithiophosphate compound 0 to 5% by weight

[0037]

Examples and Comparative Examples The additives used in the lubricating greases of the examples and the comparative examples are listed below. (1) Molybdenum dithiocarbamate (RTVanderbilt
(Molyvan A) (2) Molybdenum dithiophosphate (RTVanderbil)
(t): Molyvan L) (3) Zinc dithiophosphate (Lubrizol: Lubrizol 109)
7) (4) Copper dimethyldithiocarbamate (manufactured by Wako Pure Chemical Industries, Ltd .:
Reagents) (5) Copper stearate (Wako Pure Chemical Industries, Ltd .: Reagent) (6) Copper naphthenate (Wako Pure Chemical Industries, Ltd .: Reagent) (7) Antioxidant; Phenyl-1-naphthylamine (Ouchi Shinko Chemical Industry) (Nocrack PA)

Examples 1 to 5 and Comparative Examples 1 and 2 In mineral oil (viscosity at 100 ° C. of 13.5 mm 2 / sec), 1
A mole of diphenylmethane-4,4'-diisocyanate was reacted with 2 moles of cyclohexylamine, and the resulting urea compound was uniformly dispersed to obtain a grease. The above-mentioned additives 1 to 7 having the composition shown in Table 1 were added to this base grease, and the obtained compound was subjected to consistency N by a three-stage roll mill.
Adjusted to o.1 grade.

Comparative Example 3 A lithium soap-based grease (commercially available) containing a sulfur (S) -phosphorus (P) -based extreme pressure agent was used.

For the examples and comparative examples comprising the above lubricating grease, SRV (Schwingung Reibung und Versch)
leiss) The measurement of the coefficient of friction by a friction and wear tester and the measurement of the induced thrust by the actual joint were performed under the following conditions, and the results are also shown in Table 1. [SRV test] Specimen: Ball diameter 10 mm (SUJ2) Cylindrical plate diameter 24 mm x 7.85 mm (SUJ2) Measurement conditions: Load 100 Newton (N) Frequency 15 Hz Amplitude 1.5 mm Time 30 minutes Test temperature Room temperature Measurement item: Coefficient of friction (After 30 minutes) [Induced thrust (axial force)] Lubricating grease having the compounding ratio shown in Table 1 was sealed in a tripod-type constant velocity joint, and the induced thrust of the reference lubricating grease (Comparative Example 3) was performed under the following measurement conditions. (Axial force) The induced thrust of the example or the comparative example when the force was set to 100% was measured, and the result is also shown in Table 1. Rotation speed 150rpm Joint type Tripod joint Torque 294N Joint angle 7 ° Operating time 5min

[0041]

[Table 1]

As is clear from the results in Table 1, the friction coefficient of the lubricating greases of Comparative Examples 1 to 3 which do not contain the predetermined organocopper-based compound is higher than 0.1 in the SRV test and is measured in the actual machine test. The induced thrust was also as high as 50-100.

On the other hand, the friction coefficient of the lubricating greases of Examples 1 to 5 containing a predetermined organocopper compound in the SRV test was 0.080 or less, and the induced thrust measured in the actual machine test was 26 to 42, a value significantly lower than the same value in the comparative example.

[0044]

According to the present invention, as described above, since an organocopper compound is blended as an essential component in a lubricating grease, a lubricating oil film is formed at a high speed in a constant velocity joint. The lubricating grease for constant velocity joints has reduced sliding resistance in the axial direction of the type constant velocity joint and is less likely to cause vibration during use.

Further, a predetermined amount of the organic copper compound is blended, or when the organic copper compound is one or more organic copper compounds selected from copper stearate, copper naphthenate and copper dithiocarbamate, or a lubricating grease. When the urea thickener is obtained by blending a urea-based thickener with a base oil, the above effects are more reliably achieved.

The invention relating to a lubricating grease for a constant velocity joint in which a predetermined extreme pressure agent is blended into a lubricating grease is a lubricating grease having more excellent durability, and the axial force of the constant velocity joint is stably suppressed for a long period of time. There is an advantage that it is done.

Further, in the invention in which any of the above-described lubricating grease is sealed in the plunging type constant velocity joint for an automobile, unnecessary constant axial force is not generated in the constant velocity joint, and the vehicle body when the automobile starts and accelerates Of the vehicle, vibration of the vehicle body, or beat sound or muffled sound in the vehicle at a specific speed is reliably suppressed.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view illustrating an operation when a plunging type constant velocity joint is used.

[Explanation of symbols]

 Reference Signs List 1 outer ring 2 spherical inner ring 3, 4 track groove 5 ball 6 cage 7, 8 spherical surface A outer ring axis B shaft axis C ball rotating surface

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10M 135/18 C10M 135/18 137/10 137/10 A F16D 3/20 F16D 3/20 C // C10N 10:02 C10N 10:02 10:04 10:04 10:12 10:12 30:00 30:00 Z 30:06 30:06 40:04 40:04 50:10 50:10

Claims (6)

[Claims] 1. A lubricating grease for a constant velocity joint, wherein the lubricating grease contains an organic copper-based compound. 2. A lubricating grease sealed in a constant velocity joint, wherein the lubricating grease contains 0.1 to 10% by weight of an organic copper compound. 3. The lubricating grease for a constant velocity joint according to claim 1, wherein the organic copper-based compound is at least one organic copper-based compound selected from copper stearate, copper naphthenate, and copper dithiocarbamate. 4. The lubricating grease for a constant velocity joint according to claim 1, wherein the lubricating grease is a lubricating grease comprising a base oil and a urea-based thickener. 5. The lubricating grease for a constant velocity joint according to claim 1, wherein an organic molybdenum compound, an organic zinc compound or an extreme pressure agent used in combination thereof is added to the lubricating grease. Grease. 6. A plunging type constant velocity joint for an automobile, wherein the lubricating grease according to claim 1 is sealed in a plunging type constant velocity joint.