JP3988899B2 - Grease composition for constant velocity joints - Google Patents

Description

また比較例５として、市販有機モリブデングリースを、比較例６として、市販二硫化モリブデングリースを使用した。各グリースの性能を以下に示す試験方法に従って評価した。結果を、各グリースのちょう度（６０Ｗ）（ＪＩＳ Ｋ ２２２０による）及び滴点（℃）（ＪＩＳ Ｋ ２２２０による）とともに表１に示す。
【００１４】
1.摩擦摩耗試験
サバン型摩擦摩耗試験機を用いて摩擦係数を測定した。ここでサバン型摩擦摩耗試験機は、図２に示すように、直径４０mm×厚さ４mmの回転リング６に１／４インチの鋼球７を圧接させたものであり、摩擦係数の測定に際しては、回転リング６を周速１０８ｍ／分で回転し、荷重１kgf をかけ、回転リングの下端からスポンジ８を介して回転リングの表面にグリースを供給し、鋼球を支持するエアスライド９の動きをロードセル１０で検出した。試験時間は１０分間とし、１０分後の摩擦係数を測定した。
【００１５】
2.誘起スラスト測定試験
実ジョイント（ダブルオフセット型ジョイント）を用いて、作動角とトルクをかけて回転させた時に軸方向に発生する力を誘起スラストとして測定し、市販二硫化モリブデングリース（比較例６）の誘起スラストに対する低減率（％）で示した。
測定条件
回転数 ９００rpm
トルク １５kgf・ｍ
角度 ５°
試験時間 ５分後
【００１６】
3.耐久寿命試験
実ジョイント（ダブルオフセット型ジョイント）を用いて下記条件により実施し、評価した。
測定条件
回転数 １５００rpm
トルク ３０kgf・ｍ
角度 ５°
評価基準
◎：優れる、○：良好、△：やや不良、×：不良
【００１７】
【表１】

【００１８】
1) 硫化ジアルキルジチオカルバミン酸モリブデン Ａ（商品名Molyvan A, R.T.Vanderbilt 社製）
2) 硫化ジアルキルジチオカルバミン酸モリブデン Ｂ（商品名Molyvan 822, R.T.Vanderbilt 社製）
3) 二硫化モリブデン (Molysulfide, CLIMAX MOLYBDENUM社製, 平均粒径0.45μｍ）
4) ジチオリン酸亜鉛化合物（Lubrizol 1360, 日本ルブリゾール社製)
5) 硫黄系極圧添加剤（Anglamol 33, 日本ルブリゾール社製)
【００１９】
【発明の効果】
本発明のグリース組成物は、摩擦係数が低く、誘起スラスト低減効果が大きく、耐久性に優れている。
【図面の簡単な説明】
【図１】本発明のグリース組成物を適用するのに適したダブルオフセット型ジョイントの一例を示す一部切欠側面図である。
【図２】サバン型摩擦摩耗試験機で摩擦係数を測定する状態を示す説明図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grease composition for a constant velocity joint of an automobile, particularly a sliding type constant velocity joint. More specifically, constant velocity joints that can easily wear and easily lubricate constant velocity joints that are prone to abnormal vibrations, effectively reduce friction, suppress vibrations, and improve durability. The present invention relates to a grease composition.
[0002]
[Prior art]
In recent years, the number of FF vehicles has increased rapidly from the viewpoint of reducing the weight of automobiles and securing the interior space, and functional 4WD vehicles have also increased, and constant velocity joints (CVJ) suitable for this have been widely used. Yes. An example of a double offset joint (DOJ) used as a sliding joint in this CVJ is shown in FIG. In this double offset joint, when the rotational torque is transmitted in a state where the joint takes an operating angle, a complicated rolling and sliding motion is caused in the fitting between the track groove 3 of the outer ring 1, the track groove 4 of the inner ring 2 and the ball 5. And a force is generated in the axial direction by the frictional resistance of the sliding portion. This force is called induced thrust. In this double offset joint, the track grooves 3 are provided on the inner surface of the outer ring 1 at intervals of 60 °, and therefore, six induced thrusts are generated per rotation.
When the generation cycle of such induced thrust matches the natural frequency of the engine, vehicle body, suspension, etc., the vehicle body is induced to resonate and cause discomfort to the passenger. Is desirable. In the mounted vehicle, there is an inconvenience that a beat sound and a booming sound are generated during high-speed traveling. In addition, as automobiles become lighter and have higher output, the lubrication conditions for double offset joints become more severe, and the durability of the joints needs to be improved.
Conventional lithium-based extreme pressure greases containing sulfur-phosphorus extreme pressure additives and lithium-based extreme pressure greases containing molybdenum disulfide have problems in terms of vibration resistance and wear at high surface pressures. It is not satisfactory in terms of durability. Japanese Patent Application Laid-Open No. 62-207397 discloses a molybdenum dialkyldithiocarbamate molybdenum and one selected from the group consisting of sulfurized fats and oils, sulfurized olefins, tricresyl phosphate, trialkylthiophosphate, and zinc dialkyldithiophosphate. Alternatively, an extreme pressure grease containing a sulfur-phosphorus extreme pressure additive comprising two or more combinations as an essential component is disclosed, but it cannot be said that it is sufficient in terms of quietness and durability.
[0003]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a grease composition for a constant velocity joint having a low friction coefficient, a large effect of reducing induced thrust, and excellent durability.
[0004]
[Means for Solving the Problems]
It is known that there is a correlation between the friction coefficient and the generated induced thrust, and it is considered that a grease with a lower friction coefficient is suitable as a grease to be used under lubrication conditions that are easy to wear and that are susceptible to vibration. It is done. Therefore, various samples were evaluated for vibration resistance by measuring the coefficient of friction with a Sabang-type friction and wear tester that correlates well with the induced thrust at the actual joint, and measuring the induced thrust with the actual joint. The property was evaluated by a bench test using an actual joint. The present invention has been completed based on the knowledge obtained by such an evaluation test.
[0005]
The present invention is a grease composition for constant velocity joints comprising the following components.
(a) base oil,
(b) Diurea thickener represented by the following formula
R ¹ NH-CO-NH-C ₆ H ₄ -p-CH ₂ -C ₆ H ₄ -p-NH-CO-NHR ²
(Wherein R ¹ and R ² are the same or different, an aryl group or a cyclohexyl group having 6 or 7 carbon atoms),
(c) molybdenum sulfide dialkyldithiocarbamate,
(d) molybdenum disulfide,
(e) a zinc dithiophosphate compound, and
(f) A sulfur-based extreme pressure additive containing no phosphorus content.
Particularly preferred constant velocity joints using the composition of the present invention are sliding constant velocity joints.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the base oil of component (a) used in the present invention include mineral oil, ester synthetic oil, ether synthetic oil, hydrocarbon synthetic oil and the like. These may be used alone or in admixture of two or more.
The diurea thickener of component (b) used in the present invention is represented by the following formula.
R ¹ NH-CO-NH-C ₆ H ₄ -p-CH ₂ -C ₆ H ₄ -p-NH-CO-NHR ²
(Wherein R ¹ and R ² are the same or different, an aryl group or a cyclohexyl group having 6 or 7 carbon atoms)
Such a diurea type thickener is obtained by reaction of monoamines such as aniline, p-toluidine, cyclohexylamine and diphenylmethane-4,4′-diisocyanate.
[0007]
As the component (c) molybdenum sulfide dialkyldithiocarbamate used in the present invention, those represented by the following formula are particularly preferred.
^{[R 3 R 4 N-CS} -S] 2 -Mo 2 OmSn
(Wherein R ³ and R ⁴ represent an alkyl group having 1 to 24 carbon atoms, m + n = 4, m is 0 to 3, and n is 4 to 1.)
This compound is a known solid lubricant, for example, Japanese Patent Publication No. 45-24562 (m = 2.35-3, n = 1.65-1), Japanese Patent Publication No. 51-964 (m = 0). , N = 4), and Japanese Patent Publication No. 53-31646 (m = 0.5-2.3, n = 3.5-1.7).
[0008]
The component (d) molybdenum disulfide used in the present invention is generally widely used as a solid lubricant. This compound has a lamellar lattice structure, and is easily sheared into a thin layer by a sliding motion, hinders metal contact and has an anti-seizure effect.
However, if the amount added is large, the coefficient of friction is increased, which adversely affects vibration resistance. Moreover, wear may be increased depending on the lubrication conditions.
[0009]
Preferred examples of the component (e) zinc dithiophosphate compound used in the present invention include those represented by the following formula.
_{^{[(R 5 O) 2 -PS}} -S] 2 -Zn
(In the formula, R ⁵ represents an alkyl group having 1 to 24 carbon atoms or an aryl group having 6 to 30 carbon atoms.)
Particularly preferred are those wherein R ⁵ is a primary or secondary alkyl having 3 to 8 carbon atoms.
[0010]
Preferable examples of the sulfur-based extreme pressure additive containing no phosphorus content of component (f) used in the present invention include those having a sulfur content of 35 to 50% by weight.
In the present invention, preferably, the total content of the diurea thickener is 1 to 25% by weight, the content of molybdenum dialkyldithiocarbamate is 0.1 to 5% by weight, and the content of molybdenum disulfide is The content of the zinc dithiophosphate compound is 0.1 to 1% by weight, the content of the sulfur-based extreme pressure additive not containing phosphorus is 0.1 to 5% by weight.
[0011]
(b) Component content is less than 1 wt%, (c) Component content is less than 0.1 wt%, (d) Component content is less than 0.1 wt%, (e) Component content is 0.1 wt% If the content of the component (f) is less than 0.1% by weight, the desired effect may not be sufficiently exhibited, while the content of the component (b) is more than 25% by weight, and the component (c) More than 1% by weight, (d) more than 3% by weight, (e) more than 5% by weight, and (f) more than 5% by weight Even if it increases, the effect does not increase.
[0012]
【Example】
Next, the present invention will be described with reference to examples and comparative examples.
4100 g of base oil and 1012 g of diphenylmethane-4,4′-diisocyanate were placed in a container and the mixture was heated to 70-80 ° C. In a separate container, 4100 g of base oil, 563 g of cyclohexylamine and 225 g of aniline were taken, heated to 70-80 ° C., and added to the previous container. The mixture was allowed to react with thorough stirring for 30 minutes, and then heated to 160 ° C. with stirring and allowed to cool to obtain base urea grease A. Additives were added to this base grease A in the formulation shown in Table 1, base oil was added as appropriate, and the resulting mixture was adjusted to a consistency No. 1 grade with a three-stage roll mill.
[0013]
In the above Examples and Comparative Examples, mineral oil having the following characteristics was used as the base oil for grease.

As Comparative Example 5, a commercially available organic molybdenum grease was used, and as Comparative Example 6, a commercially available molybdenum disulfide grease was used. The performance of each grease was evaluated according to the test method shown below. The results are shown in Table 1 together with the consistency (60 W) (according to JIS K 2220) and dropping point (° C.) (according to JIS K 2220) of each grease.
[0014]
1. Friction and wear test Friction coefficient was measured using Sabang type friction and wear tester. Here, as shown in FIG. 2, the Sabang-type friction and wear tester is one in which a steel ball 7 of 1/4 inch is pressed against a rotating ring 6 having a diameter of 40 mm and a thickness of 4 mm. The rotating ring 6 is rotated at a peripheral speed of 108 m / min, a load of 1 kgf is applied, grease is supplied from the lower end of the rotating ring through the sponge 8 to the surface of the rotating ring, and the movement of the air slide 9 supporting the steel ball is performed. Detected with the load cell 10. The test time was 10 minutes, and the friction coefficient after 10 minutes was measured.
[0015]
2. Induced Thrust Measurement Test Using an actual joint (double offset joint), the axial force generated when rotating by applying an operating angle and torque was measured as induced thrust, and commercially available molybdenum disulfide grease (comparative example) The reduction ratio (%) with respect to the induced thrust of 6) is shown.
Measurement condition Rotation speed 900rpm
Torque 15kgf · m
Angle 5 °
Test time 5 minutes later [0016]
3. Durability life test An actual joint (double offset joint) was used and evaluated under the following conditions.
Measurement condition Rotation speed 1500rpm
Torque 30kgf ・ m
Angle 5 °
Evaluation criteria ◎: Excellent, ○: Good, △: Somewhat bad, ×: Bad
[Table 1]

[0018]
1) Molybdenum dialkyldithiocarbamate A (trade name: Molyvan A, manufactured by RTVanderbilt)
2) Molybdenum dialkyldithiocarbamate B (trade name Molyvan 822, manufactured by RTVanderbilt)
3) Molybdenum disulfide (Molysulfide, manufactured by CLIMAX MOLYBDENUM, average particle size 0.45μm)
4) Zinc dithiophosphate (Lubrizol 1360, manufactured by Nippon Lubrizol)
5) Sulfur-based extreme pressure additive (Anglamol 33, manufactured by Nippon Lubrizol)
[0019]
【The invention's effect】
The grease composition of the present invention has a low friction coefficient, a large effect of reducing induced thrust, and excellent durability.
[Brief description of the drawings]
FIG. 1 is a partially cutaway side view showing an example of a double offset joint suitable for applying a grease composition of the present invention.
FIG. 2 is an explanatory view showing a state in which a friction coefficient is measured with a Sabang type friction and wear tester.

Claims (2)

A constant velocity joint grease composition comprising the following components,
(a) base oil,
(b) Diurea thickener represented by the following formula
R ¹ NH-CO-NH-C ₆ H ₄ -p-CH ₂ -C ₆ H ₄ -p-NH-CO-NHR ²
(Wherein R ¹ and R ² are the same or different, an aryl group or a cyclohexyl group having 6 or 7 carbon atoms),
(c) molybdenum sulfide dialkyldithiocarbamate,
(d) molybdenum disulfide,
(e) a zinc dithiophosphate compound, and
(f) Sulfur-based extreme pressure additives not containing phosphorus other than molybdenum dialkyldithiocarbamate :
In the total composition, the content of (b) diurea thickener is 1 to 25% by weight, (c) the content of molybdenum dialkyldithiocarbamate is 0.1 to 5% by weight, and (d) molybdenum disulfide The content is 0.1 to 1% by weight, (e) the content of zinc dithiophosphate compound is 0.1 to 3% by weight, and (f) a sulfur-based extreme pressure not containing phosphorus other than molybdenum dialkyldithiocarbamate. A grease composition for constant velocity joints, wherein the additive content is 0.1 to 5 % by weight. The grease composition for a constant velocity joint according to claim 1 , wherein the constant velocity joint is a sliding constant velocity joint.

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