JP2522874B2 - Porous plain bearing - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous plain bearing used for an electric motor of industrial equipment such as automobile auxiliary equipment, audio / video / office equipment, and the like. Quality bearings.

[0002]

2. Description of the Related Art In general, a porous plain bearing has lubricating oil in its pores (holes), and has a bearing action due to the pumping action due to the rotation of the bearing and the thermal expansion of the oil due to frictional heat. It supplies oil to enable long-term bearing use. However, since the viscosity of the oil decreases in a high temperature atmosphere, the oil exudes more than necessary and is washed away, resulting in a problem that the life of the bearing is shortened and the surroundings are soiled. As a countermeasure against this, it is conceivable to use a semi-solid grease in place of the lubricating oil, and the applicant of the present application discloses in Japanese Patent Laid-Open No. 63-195416, a so-called soap using a thickener such as lithium soap. A porous plain bearing impregnated with grease has been disclosed.

However, soap grease undergoes a crystal transition at a high temperature of 100 ° C. or higher and its properties change. For example, lithium soap grease undergoes a crystal transition at 120 to 130 ° C. or higher and hardens or softens. When hardened, it affects the lubrication performance and causes an increase in torque. When softened, the leak prevention effect is reduced. Therefore, it cannot be used at a temperature higher than this. In addition to lithium, calcium, sodium and the like can be given as general soap thickeners, but both have lower heat resistance temperature than lithium, and the heat resistance limit of soap grease is about 1
20-130 degreeC. Recently, there are applications such as a fan for cooling a radiator of an automobile, which uses a sintered bearing at an ambient temperature of 120 to 130 ° C. or more, but due to this heat resistance limit, it cannot be applied to these.

Further, such a soap grease needs to be melted by heating to a temperature higher than the phase transition temperature in the manufacturing process to disperse or dissolve the soap thickener in the base oil. Equipment is required, and it is unavoidable that the manufacturing process is troublesome.

Further, in order to impregnate the porous bearing with the above-mentioned soap grease under a reduced pressure condition, the following complicated steps are required. That is, first, after placing the sintered bearing in the vacuum container, in order to remove the air in the bearing,
The vacuum state is about 0 ^-2 torr. Next, semi-solid grease is injected into the container by a pump, and the inside of the vacuum container is heated to the phase transition temperature of the grease or higher. And
The grease that has become liquid by heating is impregnated into the sintered bearing, and after the impregnation is completed, air is put into the vacuum container to bring it to normal pressure. Then, the remaining liquid grease is collected from the vacuum container by the pump, and the grease-impregnated sintered bearing is taken out from the vacuum container.

The above work (-) is regarded as one cycle, and the required cycle is repeated. In the above vacuum impregnation process, it takes about 40 minutes to bring the inside of the vacuum container into a vacuum state. Therefore, when the grease recovered once is re-injected into the vacuum container, it is cooled to be in the original semi-solid state. It is in a grease state. Therefore, the grease must be heated again to a high phase transition temperature, and by repeating heating and cooling of the grease in this way, the grease is gradually oxidized, the grease properties deteriorate, and long-term reuse is possible. There is a problem that you cannot do it. Furthermore, since the phase transition temperature is high, it requires a large amount of equipment for heating, and it takes a long time to obtain liquid grease.
There is also a problem that workability is poor and work cost is high.

[0007]

DISCLOSURE OF THE INVENTION According to the present invention, as described above, the grease using the conventional soap thickener has a viscosity of 120-1.
Since a crystal transition occurs at about 30 ° C., the torque of the bearing impregnated with this increases when used at high temperature, or grease tends to leak, and the porous grease such as a sintered bearing of soap grease. It is necessary to heat and melt the impregnating process for a high quality bearing, which solves the problem of reducing the production efficiency, and can be used under a temperature condition of 120 to 130 ° C. or higher without increasing torque or leaking grease. It is an object of the present invention to provide a porous plain bearing that does not need to be heated and melted in the manufacturing process and the process of impregnating the bearing under reduced pressure, can improve the efficiency of production equipment and production work, and contributes to the reduction of production cost.

[0008]

In order to solve the above-mentioned problems, in the present invention, grease is formed in the pores of the porous substrate.
In a porous plain bearing that is impregnated and filled with
The grease is made by adding silica airgel to the base oil and mixing.
He adopted the means of thickened grease .

The details will be described below.

The silica airgel used in the present invention comprises 2
00 ° C. does not cause crystal transition as follows soap thickener at a temperature, with the heat resistant temperature is at least 200 ° C. over more than, if there is chemical stability and affinity, in the base oil insoluble in oil Of a non-soap thickener that creates a finely dispersed structure
It is a kind.

[0011] Shi Rikaearogeru is extremely good increase consistency to the base oil, and mixed with a predetermined amount of a base oil under the normal temperature and normal humidity atmosphere, simply grease by treatment with homogenizing apparatus such as emulsifier Can be converted. By the way, minute
Excellent thickening of particle size silica airgel as described above
For use, one of the silicon atoms on the surface of the silicon dioxide particles should be
Since there is an OH group in the part, this silanol group
Three-dimensional network structure (network) in an appropriate dispersed system
It is thought to be due to the formation of Also, silica air
Rogel has a particle size of about 10 ^-2 μm, so even if it is not heated and melted unlike the conventional grease using lithium or magnesium soap as a thickener, it can be easily sintered under normal temperature atmosphere ( hole diameter). (About 1 to 10 μm).

The lubricating oil that serves as the base oil may be a mineral oil-based lubricating oil or a synthetic lubricating oil (for example, diester oil, polyol ester oil, poly-α-olefin oil, diphenyl ether oil, etc.) Various additives used in grease (for example, antioxidants, detergent dispersants, extreme pressure agents, antiwear agents, oiliness improvers, friction modifiers, viscosity index improvers, pour point depressants, rust inhibitors, defoamers) Agent, etc.) may coexist.

Further, the non-soap thickener with respect to the base oil may be 0.1 to 10% by weight. If the amount is less than the above range, the effect of preventing leakage cannot be expected, and if the amount exceeds the above range, smooth sliding is hindered, which is not preferable.

The base material of the porous plain bearing is usually composed of fine particles of iron, copper, tin, zinc, nickel, etc. or an alloy thereof in combination, but is not particularly limited. The shape of the slide bearing is not particularly limited, and the shaft and the bearing such as a flat bearing, a thrust bearing, and a journal bearing are mechanically in surface contact with each other, and the slide occurs as the bearing rotates. Any bearing may be used.
The reason why the bearing is limited to the sliding bearing is that in the rolling bearing, a porous material cannot be used for members such as balls and races (race rings) in terms of strength. However, when using a porous sintered material for the cage,
You may use what performed the same process as the above-mentioned plain bearing.

[0015]

The porous sliding bearing according to the present invention is manufactured with a grease containing a non-soap thickening agent at room temperature and impregnated in the bearing, so that the manufacturing efficiency is high and the grease has Since crystal transition does not occur even at 130 ° C. or higher, torque does not increase or grease leaks even when used in a high temperature atmosphere.

[0016]

【Example】

Example 1: Polyol ester oil (Iwa Atlas 56 manufactured by Kowa Yuka Co., Ltd.) as a base oil, and silica airgel (Aerosil R-97 manufactured by Nippon Aerosil Co., Ltd.) as a thickener.
2) 1% by weight was mixed at room temperature under normal pressure and homogenized using an emulsifying device to obtain a grease.

This grease was placed in a vacuum container together with a porous (pore diameter of 1 to 10 μm) sintered copper alloy bush-shaped slide bearing having an outer diameter of 12 mm, an inner diameter of 6 mm and a length of 6 mm, and the grease was stored at room temperature for 1 hour.
The vacuum impregnation was performed under a vacuum condition of 0 ^-2 torr.

The above grease is a liquid lubricating oil (base oil)
A two-component system embedded in a three-dimensional network structure of solid colloidal silica, which has the same leakage prevention effect as grease using lithium or magnesium soap, and at high temperatures of 100 ° C or higher. However, since no crystal transition occurred, the heat resistance was very excellent.

[0019] Reference Example 1 base oil as a polyol ester oil (Kowa Yuka Co., Ltd. Ivy Atlas 56) to, PTFE as thickened agent (manufactured by Daikin Industries, Ltd.: LUBRON L-2) 1 wt% of a surfactant The mixture was mixed under normal temperature pressure and homogenized using an emulsifying device to obtain a grease.

This grease was housed in a vacuum container together with a bushing slide bearing made of porous copper (pore diameter 1 to 10 μm) having an outer diameter of 12 mm, an inner diameter of 6 mm and a length of 6 mm, and was stored at room temperature for 1
The vacuum impregnation was performed under a vacuum condition of 0 ^-2 torr. PTFE
Is more lubricious as it is used as a low-friction material or solid lubricant, and its heat resistance is usually 300 ° C or higher. The obtained bearing has a leakage prevention effect and a significantly improved seizure resistance. Met.

[0021]

As described above, according to the present invention , the base oil is thickened with silica aerogel in the pores of the porous base material of the bearing.
Since it is a porous sliding bearing that is impregnated and filled with grease that does not cause crystal transition even at high temperatures, grease does not excessively leak from the pores of the bearing even when used in a high temperature atmosphere of 120 to 130 ° C or higher. , The torque of the supported shaft is stable and low
There is an advantage that can be kept. Further, the grease of the manufacturing process and the decompression impregnation step requires a fry to heat melted in to the bearing, the porous slide bearing of the present invention, a simple hand
There is also an advantage that it can be efficiently manufactured by the method.

Claims (1)

(57) [Claims] 1. A grease is impregnated into the pores of a porous substrate.
In the porous sliding bearing formed by filling Te, the grease
However, silica airgel was added to the base oil and mixed to thicken the
A porous plain bearing characterized by being a lease .