KR20000026786A - Operating oil for steering apparatus of automobile - Google Patents

Abstract

PURPOSE: An operating oil composition for steering apparatus of automobile is provided, which is characterized in that lubricant oil, as a base, is mixed with other agents instead of transmission oil used before. CONSTITUTION: The operating oil is composed of: lubricating oil treated by hydrogen-added contact modification process as a base; 3-4 wt.% of viscosity improving agent; 0.5-1 wt.% of anti-oxidant; 0.5-1 wt.% of anti-abrasion agent; 2.5-4.5 wt.% of dispersing agent; 0.1-0.2 wt.% of defoaming agent; and 0.8-1.5 wt.% of abrasion adjuster.

Description

Hydraulic oil composition of motorized steering device for automobile

The present invention relates to a hydraulic oil composition of a motorized steering apparatus for automobiles, and more particularly, lubricating base oil as a main component, and additives such as viscosity index improver, abrasion resistant agent, antioxidant, clean dispersant, antifoaming agent, friction modifier, etc. The present invention relates to a hydraulic oil composition of a motorized power steering apparatus for automobiles, which has been enhanced in viscosity characteristics, oxidation stability, extreme pressure resistance, abrasion resistance, shear stability, etc. at a low temperature to be suitably added to the overall power steering apparatus.

In general, by installing a power booster to the power steering device used in automobiles to reduce the operating force of the steering wheel by its back action, the power used is expressed by using a hydraulic device. Although the hydraulic fluid of the motorized steering device for automobiles used the automatic transmission oil, which requires similar characteristics as the hydraulic oil and the viscosity at low temperatures, it is manufactured according to the friction characteristics of the automatic transmission. There is a problem that noise occurs during low temperature operation. Therefore, there is an urgent need to develop a dedicated oil capable of satisfying the characteristics of the hydraulic fluid by improving the viscosity index, low temperature viscosity characteristic, wear resistance, extreme pressure, shear stability, oxidation stability, etc.

The present invention, unlike the automatic transmission oil, which is commonly used as a working oil in order to solve the above problems, the main component is a lubricant base oil, and the viscosity index improver, anti-wear agent, clean dispersant, antioxidant, antifoaming agent, friction modifier Operating oil of motorized steering device for automobile, which is made to be suitable for the characteristics of motorized steering device by improving viscosity index, low temperature viscosity property, wear resistance, extreme pressure, shear stability, oxidation stability, etc. The purpose is to provide a composition.

The present invention is mainly composed of a high viscosity index of lubricating base oil, viscosity index improver 3.0 to 4.0% by weight, antioxidant 0.5 to 1.0% by weight, anti-wear agent 0.5 to 1.0% by weight, clean dispersant 2.5 to 4.5% by weight, defoamer 0.1 to 0.2 It is characterized by the hydraulic fluid composition of the motorized steering apparatus for automobiles containing a weight% and 0.8-1.5 weight% of friction modifiers.

The present invention will be described in more detail as follows.

The working oil composition of the present invention is a component containing a conventional molybdenum dithiophosphate by containing lubricating base oil as a main component, and containing additives such as viscosity index improvers, antioxidants, antiwear agents, clean dispersants, antifoaming agents, and friction modifiers. Compared with the configured hydraulic oil composition, there is a characteristic that can obtain the effect of noise improvement due to reduced friction of the operating part. In particular, it is possible to improve the viscosity index, low temperature viscosity characteristics, wear resistance, extreme pressure, shear stability, oxidation stability and the like compared to when using the conventional automatic transmission oil as it is.

When described in more detail according to the components containing the hydraulic oil composition of the present invention as follows.

Lubricant base oil having a high viscosity index obtained by performing a hydrogenation contact reforming process is used as the lubricant base oil contained as a main component in the present invention. In the present invention, lubricating base oil is a main component, and in order to adjust the viscosity index and low temperature viscosity characteristics, an olefin copolymer system, a styrene diene copolymer system and a polymethacrylate having a weight average molecular weight of 30,000 to 40,000 as a viscosity index improver. The one selected from the acrylate system is used. The viscosity index improver is preferably contained in 3.0 to 4.0% by weight. If the content is less than 3.0% by weight, the viscosity changes with temperature change, and if it exceeds 4.0% by weight, the viscosity decrease due to shear Occurs. In addition, when the molecular weight of the viscosity index improver is out of the above range, the shear stability is lowered, the viscosity decreases due to the shear phenomenon of the operating part is lowered, the viscosity is lowered to prevent the formation of an appropriate oil film during operation, resulting in wear and noise Not desirable

In addition, in the present invention, an amine antioxidant is used as an antioxidant in addition to the main component, and 0.5 to 1.0 wt% of an amine antioxidant selected from phenylalphanaphthylamine, naphthylamine and alkyldiphenylamine is used. It is preferable to use. If the content of the amine-based antioxidant is less than 0.5% by weight, the effect of oxidation is reduced by not effectively inhibiting the formation of radical structure generated by the oxidation by heat, and when the content is greater than 1.0% by weight, The effect is not increased, resulting in uneconomic problems.

In addition, the present invention adds an anti-wear agent to increase the load resistance and wear resistance of the mechanical operating part, it is preferable that the anti-wear agent contains 0.5 to 1.0% by weight selected from alkyl disulfide, chlorate and zinc dithiophosphate. . If the content of the antiwear agent is less than 0.5% by weight, the wear resistance is increased, which causes undesirable wear of the operating part. If the content of the antiwear agent is greater than 1.0% by weight, it is not preferable because it may be precipitated by deterioration and oxidation at a high temperature.

In addition, the present invention is selected from magnesium sulfonate-based and calcium sulfonate as a clean dispersant in order to prevent the formation of sludge and varnish generated in the power steering operation unit, to maintain cleanliness and to disperse the generated sludge or varnish. Preference is given to using 2.5 to 4.5% by weight. If the content of the clean dispersant is less than 2.5% by weight, the sludge or varnish generated by the high temperature may not be effectively removed, and the cleanliness of the operating oil may not be maintained.If the content of the cleaner is more than 4.5% by weight, the effect may not be achieved due to deterioration. do.

In addition, since the power steering device circulates inside the closed system, if bubbles are generated inside the system, there is a risk of malfunction inside the hydraulic system. Since it contains 0.2% by weight, if the content of the antifoaming agent is out of the above range it can not be effective defoamer.

In addition, the present invention is a phosphate ester system as a friction modifier to prevent problems such as power loss or noise caused by friction of the mechanical operating part, that is, mutual friction of the hydraulic oil pump, mutual friction in the hydraulic system, friction between the pump shaft and the thread portion, etc. It is preferable to use 0.8 to 1.5% by weight selected from fatty acid amide and zinc dithiophosphate. If the content of the friction modifier is less than 0.8% by weight, noise or noise may occur due to friction of the operating part, and 1.5 weight. If it exceeds%, there is a disadvantage that the intended effect can not be obtained.

After inserting the above components into the blender to maintain the mixer temperature at 40 ℃ and stirred to prepare a working oil of the motorized steering device for automobiles.

The operating oil of the present invention prepared as described above can enhance the viscosity characteristics, oxidation stability, extreme pressure resistance, abrasion resistance, shear stability, etc. at low temperature to suit the characteristics of the entire power steering system.

Although this invention is demonstrated in detail based on an Example, this invention is not limited to an Example.

Example

Next, after the addition into the blender in the composition and content shown in Table 1, the blender temperature was maintained at 40 ℃ and stirred to prepare a hydraulic oil of the motorized steering device for automobiles.

Comparative Examples 1-2

Next, the hydraulic oil of the motorized steering device for automobiles was manufactured in the same manner as in the above embodiment using the compositions and contents shown in Table 1.

division Example Comparative Example 1 Comparative Example 2 Lubrication base oil (wt%) Hydrogenation Treatment - - 88.00 Hydrogenated Contact Modification 86.00 89.50 - Polymethacrylate (% by weight) 3.80 ¹⁾ 4.00 ²⁾ 3.50 ³⁾ Alkyldiphenylamine (wt%) 0.85 1.23 1.35 Zinc Dithio Phosphate (% by weight) 0.53 0.83 1.34 Clean Dispersant (wt%) Calcium Sulfonate 4.34 - - Magnesium sulfonate - 1.34 0.95 Phosphate ester (% by weight) 0.85 - 0.68 Silicone type (wt%) 0.15 0.15 0.15 Solvent Base Oil (wt%) 3.47 2.94 4.02 Red Dye (wt%) 0.01 0.01 0.01 1) Weight average molecular weight 35,0002) Weight average molecular weight 50,0003) Weight average molecular weight 55,000

Experimental Example

Physical properties of the operating oil and the conventional automatic transmission oil of the automobile-powered steering apparatus manufactured in Examples and Comparative Examples 1 and 2 were measured as follows, and the results are shown in Table 2 below.

Viscosity index was used ASTM D2270 test method, low temperature viscosity was Brookfield viscosity meter according to ASTM D2983 test method, oxidation stability is according to JIS K2514 test method, ultrasonic shear stability according to ASTM D2603 test method, 4 -Old-fashioned load resistance was tested according to ASTM D2783 test method, 4-old wear resistance according to ASTM D4172 test method.

As shown in Table 2, in the case of Examples, the viscosity index is higher than that of Comparative Examples 1 and 2, and the change in viscosity due to the change in temperature is small. It can be seen that the operability can be improved and also the shear stability is excellent, thereby reducing the decrease in viscosity due to the mechanical shear phenomenon of the moving part.

In addition, the results of the extreme pressure and abrasion resistance test results show that the result of the embodiment is superior to that of the comparative example, which causes less wear due to the mechanical load of the power steering device or the operation of the operating part. Looking at the increase in the oxidation value indicating the degree of oxidation, the oxidation stability was much better under the influence of the high temperature generated during operation.

As described above, the hydraulic fluid of the motor-driven steering apparatus of the present invention has a higher viscosity index, excellent shear stability, load resistance, compared to the automatic transmission oil used as the hydraulic fluid of the conventional power steering system. Excellent wear resistance and oxidation stability and low viscosity at low temperature improves operability when operating the power steering at low temperatures, which may result in noise, joints and steering operations that may occur when using conventional automatic transmission oils. It has the effect of greatly improving gender problems.

Claims (1)

The main component is the lubricating base oil which has undergone the hydrogenation contact reforming process, and the viscosity index improver 3.0 to 4.0 wt%, the antioxidant 0.5 to 1.0 wt%, the antiwear agent 0.5 to 1.0 wt%, the clean dispersant 2.5 to 4.5 wt%, the antifoam 0.1 to 0.2 A hydraulic fluid composition for a motor-driven steering apparatus for automobiles, characterized in that it contains% by weight and 0.8 to 1.5% by weight of friction modifier.