Method for lubricating high pressure hydraulic system using phosphate ester hydraulic fluid
AssigneeExxonMobil Research and Engineering Company
InventorsShlomo Antika, Marc-Andre Poirier, Jean-Michel Pascual, Gerard Dallemagne
Life of this patent
Estimating the term…
Abstract
The present invention is a method for operating a hydraulic system at pressures of about 4000 psi or higher, preferably about 5000 psi or higher by using as the lubricant a phosphate ester hydraulic oil comprising a fire resistant phosphate esters base stock, a viscosity index improver, an anti erosion agent, an acid scavenger. The fluid used in the present method can also contain rust inhibitors and/or antioxidants.
Claims20
A method for operating and lubricating hydraulic systems at pressure of about 4000 psi by employing as a hydraulic fluid a phosphate ester functional fluid comprising a major amount of fire resistant phosphate ester base stock and a minor effective amount of additives comprising one or more perfluoroalkyl sulfonic acid or perfluorocycloalkyl sulfonic acid, and salts of the same, anti erosion agent(s), one or more monoepoxide acid scavenger(s) and one or more viscosity index improver(s).
A method for operating and lubricating hydraulic systems at pressure of about 5000 psi and higher by employing as a hydraulic fluid a phosphate ester functional fluid comprising:
- a major amount of fire resistant phosphate ester base stock;
- from 2 to 10 wt % active ingredient, based on the total fluid, of at least on poly(alkyl acrylate) or poly(alkyl methacrylate) ester having a weight average molecular weight in the range from 45,000 to 100,000;
- from 4 to 10 wt %, based on the total fluid, of an acid control additive acid control additive of the formula
- wherein R is selected from the group consisting of an alkyl group of from 1 to 10 carbon atoms optionally containing from 1 to 4 ether oxygen atoms therein and cycloalkyl of from 3 to 10 carbon atoms, each R′ is independently selected from the group consisting of hydrogen, alkyl of 1 to 10 carbon atoms and —C(O)OR″ where R″ is alkyl of from 1 to 10 carbon atoms and 0 to 4 ether oxygen atoms therein or cycloalkyl of from 3 to 10 carbon atoms, and R′″ is selected from the group consisting of hydrogen, alkyl of from 1 to 10 carbon atoms and —C(O)OR″ where R″ is alkyl of from 1 to 10 carbon atoms optionally containing from 1 to 4 ether oxygen atoms therein or cycloalkyl of from 3 to 10 carbon atoms;
- from 0.01 to 0.15 wt %, based on the total fluid, of a perfluoroalkyl or perfluorocycloalkyl sulfonic acid, or a metal salt of the same, or mixture of these sulfonic acid acids and metal salts, where the alkyl groups encompass 1 to 10 carbon atoms and the cycloalkyl groups from 3 to 10 carbon atoms;
- from 0 to 1.0 wt %, based on the total fluid, of one or more rust inhibitors;
- and
- from 0 to 3 wt %, based on the total fluid, at least one of aminic or phenolic antioxidants.
Dependencies are inferred from the claim text.