Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic compound containing boron
Reexamination Certificate
2000-06-02
2001-10-16
Johnson, Jerry D. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic compound containing boron
C508S291000, C508S294000, C508S431000, C508S432000, C508S434000, C508S436000, C508S438000, C508S442000
Reexamination Certificate
active
06303546
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a traction drive fluid. More particularly, the present invention is concerned with a traction drive fluid which has excellent wear resistance and excellent scoring resistance, is capable of suppressing surface damage such as peeling of a friction material and in particular, is well suited for use as a lubricating oil for a traction drive continuously variable transmission used in an automobile.
2. Description of the Related Arts
A traction drive fluid is employed in a traction drive apparatus (friction drive apparatus by rolling contact drive), for instance, continuously variable transmissions for an automobile, continuously variable transmissions for industrial use and the like. In particular, a traction drive continuously variable transmission used in an automobile is equipped with a starting/running device and a lock-up clutch. Accordingly, the traction drive fluid employed therein is called upon to have lubricating characteristics for lubricating portions of high surface pressure such as gears, roller-bearings and traction drive portions, for instance, to have lubricity and peel resistant durability for a clutch friction material further to wear resistance and scoring (seizure) resistance therefor.
In recent years, automobile transmissions show a tendency to be miniaturized, light-weighted and maximized in transmission capacity. This is also the case with a traction drive continuously variable transmission. The aforesaid technological tendency accelerates heat generation at lubricating portions and brings about an increase in thermal load for a lubricating oil used therein. As a result, the traction drive fluid used therein is called upon to have heat resistance and besides, a high lubricating performance and adaptability to materials for lubricating portions under the condition of an elevated temperature.
Such being the case, the aforesaid traction drive fluid is required to be imparted with friction characteristics for a friction material (wet clutch) and at the same time, wear resistance and scoring resistance, thus bringing about a trend towards the use of an additive having high reactivity with a metallic surface.
However, an additive having high reactivity with a metallic surface, that is, an active additive is highly active also with cellulose which is a principal component of a friction material. Thus the aforesaid active additive suffers from such disadvantages that accelerate cutoff of cellulose structure (cutoff of cellulose fibers in the form of rings and chains) and elution thereof in oil or the like, and are more prone to cause damage such as peeling to a friction material.
In such circumstances, there has eagerly been desired the development of a traction drive fluid capable of alleviating and suppressing the reaction with cellulose which reaction is responsible for peeling and the like of a friction material, without impairing its wear resistance and scoring resistance of a steel material element.
There has only been reported the working effect of a metal base detergent (calcium sulfonate having a total base number of 300 ) as a technique for alleviating and suppressing the peeling damage to a friction material (refer to preliminary prints for scientific lecture, Japan Automotive Engineering Society, 952, 9535297, 1995-5 ). Nevertheless, in the case of blending the above-mentioned metal base detergent dispersant, there is caused the problem of a fear of clogging the pores on the surface of a friction material, thereby deteriorating the lubricating characteristics and the like.
SUMMARY OF THE INVENTION
Under such circumstances, a general object of the present invention is to provide a traction drive fluid which has excellent wear resistance and excellent scoring resistance, is capable of suppressing surface damage such as peeling of a friction material and in particular, is well suited for use as a lubricating oil for a traction drive continuously variable transmission used in an automobile.
Other objects of the present invention will be obvious from the text of this specification hereinafter disclosed.
In view of the foregoing, intensive extensive research and investigation were accumulated by the present inventors in order to achieve the above-mentioned objects. As a result, it has been found that the objects can effectively be attained by a traction drive fluid which comprises a base oil blended with an active phosphate ester base compound, a boron-containing imide base dispersant and a boron-free imide base dispersant each at a specific proportion based on said base oil. The present invention has been accomplished by the foregoing findings and information.
Specifically, the present invention provides a traction drive fluid which comprises a base oil blended with (A) an active phosphate ester base compound, (B) a boron-containing imide base dispersant and (C) a boron-free imide base dispersant in such blending amounts that the phosphorus content derived from the component (A) and the boron content derived from the component (B) are made to be in the range of 100 to 600 ppm by weight and at least 60 ppm by weight, respectively based on said base oil, and the boron-free imide base dispersant (C) is blended so that the ratio by weight of the nitrogen in the component (C) to the boron in the component (B) (N/B ratio) is made to be at least one (1).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The base oil in the traction drive fluid according to the present invention is not specifically limited, but may be properly and optionally selected for use from the base oils that have heretofore been customarily used for a traction drive fluid. The above-mentioned base oils are exemplified by mineral oils such as paraffin base mineral oil, naphthene base mineral oil and intermediate base mineral oil, and synthetic oils such as a saturated hydrocarbon compound, an ester compound and an ether compound each having at least one member selected from the group consisting of cyclohexane ring, decalin ring, bicycloheptane ring and bicyclooctane ring. In particular, as the saturated hydrocarbon compound having a cyclohexane ring, there are usable the compounds described in Japanese Patent Application Publication Numbers 80191/1991 (Heisei-3) , 52958/ 1990 (Heisei-2) and 39419/1994 (Heisei-6) and the like; as the saturated hydrocarbon compound having a decalin ring, there are usable the compounds described in Japanese Patent Application Publication Number 43392/1985 (Showa-60) and the like, as the saturated hydrocarbon compound having a bicycloheptane ring, there are usable the compounds described in Japanese Patent Application Publication Numbers 31914/1993 (Heisei-5), 103387/1995 (Heisei-7) and the like; and as the saturated hydrocarbon compound having a bicyclooctane ring, there are usable the compounds described in Japanese Patent Application Laid-Open Number 9134/1993 (Heisei-5) and the like.
In the present invention, the base oil is used usually in an amount of at least 80% by weight based on the traction drive fluid, and may be used alone or in combination with at least one other species.
The active phosphate ester base compound to be used as the component (A) in the traction drive fluid according to the present invention is not specifically limited, but may be properly and optionally selected for use in accordance with the situation from the well known active phosphate ester base compounds that have heretofore been used as an extreme pressure agent or an anti-wear agent, for instance, acidic phosphate esters, phosphite esters, acidic phosphite esters and hypophosphite esters.
As the active phosphate ester base compound to be used in the traction drive fluid according to the present invention, there are preferably used the acidic phosphate esters and phosphite esters represented by the general formula (I):
wherein A is hydrogen atom or hydroxyl group, m is 0 or 1 with the proviso that A is hydroxyl group when m is 0, and A is hydrogen atom or hydroxyl group when m is 1, and R
1
and R
2
Arakawa Yoshie
Goto Nobuo
Hata Hitoshi
Miyaji Tomomi
Murakami Yasuhiro
Idemitsu Kosan Co. Ltd.
Johnson Jerry D.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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