JPH01132690A - Bearing - Google Patents

Abstract

PURPOSE:To prepare a bearing which has a small low-temp. dynamic torque and excellent high-temp. durability and abrasion resistance, by opposing a bearing surface provided on a bearing member to a receiving surface provided on a shaft through a particular lubricant. CONSTITUTION:A straight-chain perfluoroalkyl polyether having a kinetic viscosity (40 deg.C) of 5.5-20cSt is mixed with 0.1-10wt.% perfluoroalkyl polyether optionally having a carboxylic acid group in its terminal to prepare a lubricant. A bearing surface provided on a bearing member is opposed to a receiving surface provided on a shaft through the aforesaid lubricant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to bearings used in various fields such as audio equipment, video equipment, and office equipment.

[Conventional technology]

Hydrodynamic grooved bearings and plain bearings use mineral oil, synthetic hydrocarbon oil, synthetic oil such as diester oil, polyol ester oil, diphenyl ether oil, silicone oil, mixtures of these oils, and greases based on these oils as lubricants. It is used.

[Problem that the invention seeks to solve]

The load capacity of hydrodynamic grooved bearings and plain bearings is proportional to the viscosity of the lubricant used. Synthetic oils such as mineral oils and synthetic hydrocarbon oils that have traditionally been used as lubricating oils have a large viscosity change with temperature changes, so oils that satisfy the required load capacity at high temperatures have a large viscosity increase at low temperatures ( This increases the bearing torque. On the other hand, if an oil with a viscosity that provides the optimal dynamic torque for the bearing at low temperatures is selected, the viscosity decreases at high temperatures, resulting in insufficient load capacity. Furthermore, although some silicone oils have a small change in viscosity with respect to temperature changes, they have poor boundary lubricity, so repeated starting and stopping of the bearing increases wear and durability.

For example, video tape recorders (hereinafter referred to as VTRs) that use hydrodynamic grooved bearings and plain bearings have lower vibration and noise than VTRs that use ball bearings, but synthetic oils such as conventional mineral oils and synthetic hydrocarbon oils are If a VTR is used, the operating torque at low temperatures will be several times larger than that of a VTR using ball bearings. Therefore, conventional hydrodynamic grooved bearings and plain bearings that use synthetic oils such as mineral oil or synthetic hydrocarbon oil as lubricants are
Although this method is applicable to TRs, it is difficult to apply to portable VTRs that are used outdoors or in cold regions.

The object of the present invention is to provide a bearing that has low dynamic torque at low temperatures, good high-temperature durability, and good wear resistance.

[Means for solving problems]

The basic structure of the present invention is that a bearing surface provided on a bearing member faces a bearing surface provided on a shaft body via a lubricant, and a temperature of 5.
A linear perfluoroalkyl polyether with a kinematic viscosity of 5 to ZOcSt is used as a lubricant. An embodiment of this invention is a linear perfluoroalkyl polyether having a kinematic viscosity of 5.5 to 20 cSt at 40°C, and 0.1 to 10% by weight of perfluoroalkyl polyether having a terminal carboxylic acid. Use mixed lubricants.

[Effect]

Either the lees receiving member or the shaft body rotates or moves linearly relative to the other. 5. At 40℃ used as a lubricant.
Linear perfluoroalkyl polyether, which has a kinematic viscosity of 5 to 20 cS L, has a relatively low amount of evaporation even at high temperatures and has good bearing durability, and its viscosity changes little with temperature changes, so it is suitable for use at low temperatures. When 0.1 to 10% by weight of perfluoroalkyl polyether containing a bonic acid is mixed with a small increase in viscosity and the dynamic torque of the bearing is small, the boundary lubrication performance is improved by the adsorption of carboxyl groups to the metal surface, and the bearing starts. This reduces wear when stopped and further improves the durability of the bearing.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

In Fig. f51, a steel ball made of 5US440C stainless steel for a ball bearing is press-fitted and attached as a thrust receiving member 53 to one end of the inner peripheral surface of the housing 40 made of an aluminum alloy. The thrust receiving member 53 and the housing 40 constitute a bearing member 70, and the lower surface of the thrust receiving member 53 forms a convex spherical thrust bearing surface 52. On the inner peripheral surface of the housing 40, cylindrical radial bearing surfaces 55 are provided at two locations spaced apart in the axial direction. A generating groove 42 is provided respectively. An inner circumferential groove 59 is provided on the inner circumferential surface of the housing 4o at a location between two grooves 42 for generating dynamic pressure, and a groove made of heat-treated 5OS440C stainless steel is provided on the inner circumference of the housing 40 The shaft body 61 has a cylindrical radial bearing surface 62 that faces the radial bearing surface 55 with a lubricant in the radial bearing clearance 72 interposed therebetween. The upper end surface of the shaft body 61 has a thrust bearing surface 63 that faces the thrust bearing surface 52 via a lubricant, and this thrust bearing surface 63 is a concave spherical surface having a radius of curvature larger than the radius of curvature of the thrust bearing surface 52. be. The inner circumferential surface of the housing 40 has a fluid drainage groove 65 at a location 64 where it contacts the thrust receiving member, through which the fluid between the thrust receiving member 53 and the shaft body 61 communicates to the outside of the housing 40 .

The number of fluid drainage grooves 65 is the same as the number of grooves 42 for generating dynamic pressure, and these fluid drainage grooves 65 are directly connected to the grooves 42 for generating dynamic pressure.

Therefore, when the shaft 61 is inserted into the inner circumferential surface of the housing 40, the last bearing surface 52 between the shaft 61 and the thrust receiving member 53 rotates in a state in which it is in point contact with the thrust receiving surface 63. In addition, due to the pumping of the groove 42 for generating dynamic pressure last month, the pressure of the fluid in the radial bearing clearance 72 between the radial bearing surface 55 and the radial bearing surface 62 increases, and the radial bearing surface 55 rotates without contact.

The temperature between the radial bearing surface 55 and the radial bearing surface 62 and between the thrust bearing surface 52 and the thrust bearing surface 63 is 40°C.
A linear perfluoroalkyl polyether having a kinematic viscosity of 5.5 to 20 cSt is incorporated as a lubricant. Or, the radial bearing surface 55 and the radial bearing surface 62
A lubricant having a kinematic viscosity of 5.5 to 20 cSt at 40° C. is placed between the thrust bearing surface 52 and the thrust bearing surface 63.

Examples of the above-mentioned linear perfluoroalkyl polyethers include those having the following structural formula numbers. In addition, p, q, m, and n in the following structural formula are all 2
is an integer greater than or equal to

(1) CFp ((OCF2-CF2)I)-(OC
F2) Q) l-OCF3(2) F (CF2 C
F2-CF2 0) n-CzFs These linear perfluoroalkyl polyethers have branched-CF groups in their chemical structure, so molecular rotation is easy and the viscosity index is mixed. It is characterized by a low pour point. Furthermore, when compared with perfluoroalkyl polyethers having central branches, the molecular weight is high if the viscosity is the same, so linear perfluoroalkyl polyethers have a small amount of evaporation even if they have low viscosity.

Perfluoroalkyl with carboxylic acid at the end (3)
HOOC-CF2- (OCF2- CF2)r-(O
CF2)s-0CF2-0OH COOII CF3 (6) F-(CF2-CF2-CF2-0)n-CF
Examples of 2-CF2-COOH having a carboxylic acid at the terminal include those having a carboxylic acid bonded to both ends or one end as described above.

Table 1 shows the test results of the evaporation amount of linear perfluoroalkyl polyether and synthetic hydrocarbon oil.

Roalkyl boriethers are not currently produced, but their evaporation rate is thought to be relatively large. The linear perfluoroalkyl polyether preferably has a kinematic viscosity of 5.5 cSt or more at 40° C. in order to reduce the amount of evaporation at high temperatures.

Moreover, FIG. 3 is a chart showing the relationship between ambient temperature and unmanned driving torque of linear perfluoroalkyl polyether and synthetic hydrocarbon oil. (i), (ii), (iii)
and (iv) are all linear perfluoroalkyl polyethers, and (i) has a kinematic viscosity of 30 at 40°C.
cSt, and (ii) has a kinematic viscosity of 20 cS at 40°C.
t, and (iii) has a kinematic viscosity of 10 cSt at 40°C.
and (iv) has a kinematic viscosity of 5.5 cSt at 40°C. (v) is a synthetic hydrocarbon oil and has a kinematic viscosity of 18 cSt at 40°C, making it unusable. The non-dimensional torque is 3
The kinematic viscosity at 40° C. of the linear perfluoroalkyl polyether is preferably 20 cSt or less.

In order to ensure the load capacity and durability of the bearing at high temperatures and to satisfy the low torque performance of the bearing at low temperatures, the kinematic viscosity of linear perfluoroalkyl polyether at 40°C must be 5. It is preferable that it is .5-2QcSt.

Incidentally, linear perfluoroalkyl polyether having a kinematic viscosity of 5.5 to 20 cSt at 40° C. has significantly better boundary lubrication performance than silicone oil.

Table 2 shows how a lubricant prepared by mixing linear perfluoroalkyl polyether with a weight of 1.0 cSt at 40°C and perfluoroalkyl polyether having a carboxylic acid at the terminal was applied to the bearings shown in Figures 1 and 2. Use bearing member 70ヲ3
．． OOOrpm, load m 100 gf 7200 hours E r
The amount of wear on the thrust receiving surface 52 when rolling and the mixing ratio of perfluoroalkyl polyether having a carboxylic acid at the terminal to the linear perfluoroalkyl polyether on the thrust receiving surface is 0.1 to 10 il1%. preferable. 0.
If it was less than 1% by weight, there was little improvement in IT wear performance, and if it exceeded 10% by weight, no significant improvement was observed.

Furthermore, the kinematic viscosity of a lubricant prepared by mixing a linear perfluoroalkyl polyether and a perfluoroalkyl polyether having a carboxylic acid at the end is 5.5 to 2 at 40°C.
It is preferable that it be 0 cSt.

In addition, the housing 40, the thrust receiving member 53, and the shaft body 6
In order to prevent rust from forming on the housing 40, it is preferable to use aluminum alloy, free-cutting yellow body, or plastic material, and the shaft body 61 is preferably made of 5US440C.

It is preferable to use a material that does not easily rust, such as 5US630.5US420J2.

Furthermore, a groove 42 for generating dynamic pressure may be provided in at least one of the radial bearing surface 55 and the radial bearing surface 62.

Further, the radial bearing surface 55 and the radial bearing surface 62 may constitute a sliding bearing.

Furthermore, although the thrust bearing surface 52 and the thrust bearing surface 63 are in point contact and constitute a sliding bearing, the thrust bearing surface 52
Since the thrust bearing surface 52 and the thrust bearing surface 63 face each other and make point contact with each other via the lubricant, boundary lubricity is improved, and wear between the thrust bearing surface 52 and the thrust bearing surface 63 is reduced.

Note that both the thrust bearing surface 52 and the thrust bearing surface 63 are planar, and the thrust bearing surface 52 and the thrust bearing surface 6
A dynamic pressure type grooved thrust bearing may be formed by providing a groove for generating dynamic pressure on at least one of the grooves and the groove.

Furthermore, the housing 40 and the thrust receiving member 53 may be integrally formed into a single member f7.

Further, either one of the bearing member 70 and the shaft body 61 may perform oral motion or linear motion. It may be equipped with only a radial bearing or only a thrust bearing.

〔Effect of the invention〕

According to the bearing of this invention, 5.5~20cS at 40°C
By using a linear perfluoroalkyl polyether with a kinematic viscosity of can be obtained. 40℃ again
A linear perfluoroalkyl polyether having a kinematic viscosity of 5.5 to 20 cSt is added with a perfluoroalkyl polyether having a carboxylic acid terminal at 0.1 to 10 cSt.
Boundary by weight of weight? The iL lubricity is further improved, the amount of wear during starting and stopping of the bearing is significantly reduced, and the durability of the bearing is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a bearing showing an embodiment of the present invention, fj
Fig. S2 is a sectional view of the bearing member, and Fig. 3 is a chart showing the relationship between ambient temperature and uncontrolled torque. In the figure, 52.55
is a bearing surface, 61 is a shaft body, 62, 63 is a bearing surface, and 70 is a bearing member. Patent applicant: NSK Ltd. 7! ″L′)cr′L′)OO ba〕po) ba)-heha ri w!

Claims (1)

[Claims] 1. In a bearing in which a bearing surface provided on a bearing member faces a bearing surface provided on a shaft body via a lubricant, the lubricant is heated to 40°C.
A bearing comprising a linear perfluoroalkyl polyether having a kinematic viscosity of 5.5 to 20 cSt. 2. The bearing according to claim 1, wherein the lubricant comprises 0.1 to 10% by weight of perfluoroalkyl polyether having a carboxylic acid terminal.