JPH09177766A - Dynamic pressure bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing device provided with the lubricating oil small in the viscosity change to the temperature change and excellent in the wettability to the metal. SOLUTION: A shaft 1 is inserted in a bearing member 5 in a dynamic pressure bearing device. Dynamic pressure generating grooves 6, 7 are formed in the shaft 1. A dynamic pressure generating groove 8 is formed in a bottom plate 3 of the bearing member 5. The lubricating oil 10 is filled between the bearing member 5 and the shaft 1. The lubricating oil 10 is the oil in which 1-3wt.% phthalic acid mono-ethyl ester is added to di-2-ethyl hexyl sebacate as the base oil. Di-2-ethyl hexyl sebacate is small in the viscosity change to the temperature change, while phthalic mono-ethyl ester is excellent in affinity to the ester oil and metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure bearing device for supporting a rotating body with respect to a bearing member by generating a dynamic pressure in lubricating oil.

[0002]

2. Description of the Related Art Conventionally, as a dynamic bearing device of this kind,
There is one in which an ester-based oil such as diester or polyol ester is interposed as a lubricating oil between a rotating body and a bearing member supporting the rotating body. Since this ester oil has excellent fluidity and heat resistance at low temperatures, the viscosity change with temperature change is small, and stable dynamic pressure can be generated even if the temperature changes.

[0003]

However, the ester-based oil alone has a drawback that it is difficult to form an oil film on the rotating body or the bearing member because the affinity with metal is insufficient.
For this reason, there is a problem in that, particularly at the time of starting or stopping, the oil film is liable to come into direct contact with the rotating member and the bearing member or boundary lubrication is likely to occur, resulting in insufficient lubrication.

Therefore, an object of the present invention is to provide a dynamic pressure bearing device provided with a lubricating oil which has a small change in viscosity with respect to a change in temperature and is excellent in wettability with respect to metal.

[0005]

In order to achieve the above object, a dynamic pressure bearing device of the present invention comprises a rotating body and a bearing member supporting the rotating body, and a bearing member facing the rotating body. In a dynamic pressure bearing device in which a dynamic pressure generating groove is formed on at least one of the facing surface or the facing surface of the rotating body facing the bearing member, an ester oil is used as a base oil between the rotating body and the bearing member. The lubricating oil containing an organic acid ester or an inorganic acid ester having a polar group is interposed.

The above-mentioned ester oil has a small change in viscosity with temperature. And, the organic acid ester or inorganic acid ester having the polar group is of the same system as the ester oil and has an affinity for the ester oil, and since it has a strong polarity, There is an affinity. Therefore, a lubricating oil to which an organic acid ester or an inorganic acid ester having a polar group is added using the above-mentioned ester oil as a base oil has a small change in viscosity with respect to temperature changes, and further has improved wettability with respect to the metal surface. Therefore, according to the hydrodynamic bearing device of the present invention, the rotating body can be stably supported even when the temperature changes, and the oil film is unlikely to run out at the time of starting or stopping, so that the rotating body can always be stably supported. As the ester oil, conventionally known diesters, polyol esters and the like are used. As the diester, di-2-ethylhexyl adipate (D
OA), di-isodecyl adipate (DIDA), diisononyl adipate (DINA), azelaic acid di-2
-Ethylhexyl (DOZ), di-2-ethylhexyl sebacate (DOS) and the like. Examples of the polyol ester include esters of hindered alcohols such as neopentyl glycol, trimethylolpropane and penerythritol. These base oils are used alone or in combination in consideration of torque characteristics and lubricating life. Examples of the inorganic acid ester having a polar group include trioleyl phosphate, tricresyl phosphate and tributyl phosphate, and the organic acid ester having a polar group includes an acidic phthalic acid (mono) ester such as phthalic acid. In addition to monoethyl ester, phthalic acid monomethyl ester, phthalic acid monophenyl ester, phthalic acid monobenzyl ester, there are sorbitan monooleate, pentaesulite monooleate and the like.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment of a dynamic pressure bearing device of the present invention. This dynamic pressure bearing device is a SU as a rotating body.
A metal shaft 1, a metal sleeve 2 and a metal bottom plate 3 made of austenitic stainless steel such as S303 and SUS304 are provided. Collar 3 of bottom plate 3
a is a wide mouth portion 2a formed at the axial end of the sleeve 2.
And is fixed. The sleeve 2 and the bottom plate 3 form a bearing member 5. Further, two dynamic pressure generating grooves 6 are formed on the outer peripheral surface of the shaft 1 at predetermined intervals in the axial direction.
And 7 are formed. Further, a spiral dynamic pressure generating groove 8 as shown in FIG. 2 is formed on the end surface 3b of the bottom plate 3.

A lubricating oil 10 is filled between the shaft 1 and the bearing member 5. This lubricating oil 10
Is an oil in which phthalic acid monoethyl ester as an organic acid ester having a polar group of 1 to 3% by weight is added, using ester oil di2 ethylhexyl sebacate as a base oil.

In the dynamic pressure bearing device having the above structure, when the shaft 1 rotates with respect to the bearing member 5, the dynamic pressure generating grooves 6 and 7 of the shaft 1 generate a dynamic pressure in the lubricating oil 10 so that the shaft 1 is supported by the bearing member. 5 is supported in the radial direction. At the same time, the dynamic pressure generating groove 8 formed in the bottom plate 3 generates a dynamic pressure in the lubricating oil 10 to support the shaft 1 in the axial direction.

The di-2-ethylhexyl sebacate used as the base oil of the lubricating oil 10 has a small change in viscosity with temperature. The phthalic acid monoethyl ester added to the base oil has an affinity for the di-2-ethylhexyl sebacate and, in addition, a CO group or an OH group as a polar group is easily adsorbed on the metal surface. Good affinity with. Therefore, the lubricating oil 10 has a small change in viscosity with respect to a change in temperature and has a good wettability with respect to the metal surface. Therefore, according to this dynamic pressure bearing device, the shaft 1 can be stably supported even when the temperature changes, and the oil film is unlikely to run out at the time of starting or stopping, so that the shaft 1 can always be stably supported.

[0012]

As is apparent from the above, the dynamic pressure bearing device of the present invention uses an ester oil as a base oil and an inorganic acid ester having a polar group or a polar group between the rotor and the bearing member. The lubricating oil to which the organic acid ester has is added.

The ester-based oil used as the base oil has a small change in viscosity with respect to temperature changes, and the inorganic acid or organic acid ester added to the base oil has a good affinity for the ester-based oil and also has a high affinity with metals. Good affinity. Therefore, the above-mentioned lubricating oil has a small change in viscosity with respect to a change in temperature, and also has good wettability with respect to the metal surface. Therefore, according to the hydrodynamic bearing device of the present invention, the rotating body can be stably supported even when the temperature changes, and the oil film is unlikely to run out at the time of starting or stopping, so that the rotating body can always be stably supported. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an embodiment of a dynamic pressure bearing device of the present invention.

FIG. 2 is a plan view showing a dynamic pressure generation groove formed in the bottom plate of the above embodiment.

[Explanation of symbols]

1 ... Shaft, 2 ... Sleeve, 2a ... Wide mouth part, 3 ... Bottom plate, 3a ... Collar part, 5 ... Bearing member, 6, 7, 8 ... Dynamic pressure generating groove, 10 ... Lubricating oil.

Claims (1)

[Claims] 1. A dynamic pressure generation is provided on at least one of a facing surface of a bearing member facing the rotating body and a facing surface of the rotating body facing the bearing member, comprising a rotating body and a bearing member supporting the rotating body. In a hydrodynamic bearing device in which a groove is formed, a lubricating oil, in which an organic acid ester having a polar group or an inorganic acid ester is added, is used as an ester oil as a base oil between the rotating body and the bearing member. A hydrodynamic bearing device characterized by being made.