Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic phosphorus compound – wherein the phosphorus is...
Patent
1997-06-10
1999-05-11
Johnson, Jerry D.
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic phosphorus compound, wherein the phosphorus is...
508439, C10M141/10
Patent
active
059027770
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a hydraulic working oil composition. More particularly, it pertains to a hydraulic working oil composition which is excellent in oxidation stability and lubricating performance under high pressure, is serviceable for a long period of time, and exhibits stable working characteristics by eliminating a phenomenon of cylinder waviness, that is, a phenomenon of causing vibration and/or abnormal noise between a cylinder and a piston, between a rod and a (sealing) guide, or the like in a hydraulic working portion of hydraulic machinery.
BACKGROUND ART
A hydraulic working oil, which is a power transmission fluid used for such actuation as power transmission, force control and force cushioning in a hydraulic system including hydraulic machinery and equipment, also fulfils the function of lubricating sliding parts.
With the recent progress towards miniaturization and high output of modern hydraulic machinery and equipment, a working pressure has increasingly been made higher, for example, the previous pressure of 14 to 20 MPa has been increased to the present pressure of 30 MPa or higher, while an oil tank has been directed to a small capacity. Such being the case, the heat load imposed upon a working oil has been made severer than ever before, thus bringing about several problems such as premature deterioration of a working oil, sludge formation therein, the phenomenon of cylinder waviness and malfunction of hydraulic machinery or equipment.
As a hydraulic working oil, there has heretofore been used a zinc alkyldithiophosphate (ZnDTP) which is imparted with both antioxidative and lubricating capabilities. However in the case of such a hydraulic working oil, the above-mentioned ZnDTP is thermally decomposed at locally hot portions that are caused by the heat of bubble compression accompanying the trend towards high pressure. The aforesaid decomposition results in several problems such as sludge formation, the resultant malfunction of hydraulic machinery and equipment and/or the generation of an abnormal odor.
Under such circumstances, an investigation has been made on the simultaneous use of the ZnDTP and a metallic detergent. Nevertheless, such combination is not satisfactory with regard to the service life thereof, and the problem of the phenomenon of cylinder waviness at the time of operation due to high pressure still remains unsolved.
DISCLOSURE OF THE INVENTION
It is the general object of the invention to provide, in such circumstances, a hydraulic working oil composition capable of effectively preventing premature deterioration of the working fluid accompanying the trend towards high pressure and the sludge formation therein, being serviceable for a long period of time and at the same time, exhibiting stable working characteristics by eliminating a phenomenon of cylinder waviness.
In view of the foregoing, intensive research and investigation were accumulated by the present inventors in order to develop a hydraulic working oil having favorable properties as mentioned hereinbefore. As a result, it has been found that the above-mentioned object can be achieved with enhanced oxidation stability and lubricating performance under high pressure by blending an aminic antioxidant, a phenolic antioxidant, a phosphoric ester and an fatty acid amide or a polyhydric alcohol-based ester with a base oil having a specific property each at a specific proportion. The present invention has been accomplished on the basis of the above-mentioned finding an information.
Specifically, the present invention provides a blend, a base oil having a C.sub.A content of at most 5%, 0.01 to 5% by weight of an (A) aminic antioxidant, 0.01 to 5% by weight of a (B) phenolic antioxidant, 0.01 to 5% by weight of a (C) phosphoric ester and 0.001 to 5% by weight of a (D) fatty acid amide and/or polyhydric alcohol ester each based on the whole amount of said composition.
The preferred embodiments of the present invention include: (1) wherein the base oil has a kinematic viscosity at 40.degree.
REFERENCES:
patent: 2205183 (1940-06-01), Woodhouse
patent: 3652411 (1972-03-01), Commichau
patent: 3723315 (1973-03-01), Sullivan
patent: 3931022 (1976-01-01), Chesluk et al.
patent: 3970570 (1976-07-01), Pratt et al.
patent: 4917809 (1990-04-01), Zinke et al.
patent: 5024775 (1991-06-01), Hanlon et al.
patent: 5064546 (1991-11-01), Dasai
Hashimoto Katsumi
Sasaki Akira
Idemitsu Kosan Co. Ltd.
Johnson Jerry D.
LandOfFree
Hydraulic working oil composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic working oil composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic working oil composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-245570