Rolling bearings

Abstract

To provide a rolling bearing that makes it possible to quickly detect the deterioration state of a grease composition filled into the rolling bearing, requiring only a small amount of grease, even for the type of deterioration caused by the mixing of foreign matter such as iron powder, as well as the type of deterioration caused by oxidation and heat.SOLUTION: A rolling bearing holds a rolling element between an outer ring and an inner ring so that it can roll freely, and is filled with a grease composition containing a thermosensitive agent. Preferably, the grease composition has a mixing consistency (25°C) of 240 or less. Preferably, the grease composition has a thermal conductivity of 150 mW / (m K) or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rolling bearing, and more particularly to a rolling bearing capable of detecting the deterioration state of a grease composition filled therein. [Background technology]

[0002] Grease compositions are used in various mechanical device components, including rolling bearings and reducers. Abnormal wear is one cause of failure of these components, and when abnormal wear occurs, foreign matter such as iron powder gets mixed into the grease composition, causing the grease composition to deteriorate. There are several factors that can cause the deterioration of a grease composition, such as deterioration of the grease composition due to changes in components caused by heat or deterioration of the grease composition due to oxidation.

[0003] Various methods for detecting the deterioration, etc., of lubricating oils used in the same applications as grease compositions have been studied. For example, Patent Document 1 discloses a color sensor that is attached to a mechanical device itself, and the condition of the lubricating oil can be detected by the color sensor.

[0004] However, since grease compositions have lower fluidity and lower light transmittance than lubricating oils, it is difficult to analyze the deterioration of grease compositions.

[0005] Regarding deterioration of a grease composition limited to that caused by the inclusion of iron powder, for example, Patent Document 2 discloses a failure prediction device that predicts failure of a part to be measured by measuring the concentration of iron powder in a grease composition used in the part to be measured from the disruption of the magnetic balance between an excitation coil and a detection coil. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5980591 [Patent Document 2] Patent No. 5188088 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the technology disclosed in Patent Document 2 measures the iron powder concentration, so a relatively large amount of grease composition is required to detect the deterioration state of the grease composition. Furthermore, the sensor part of the failure prediction device needs to be installed at the desired detection location, which requires a considerable amount of time and cost from the manufacture and installation of the device to the prediction stage. Furthermore, this technology is limited to detecting deterioration due to iron powder contamination in the grease composition, and is unable to detect deterioration due to changes in the components of the grease composition caused by oxidation or heat.

[0008] Therefore, an object of the present invention is to provide a rolling bearing that can detect the state of deterioration of a filled grease composition, which can detect deterioration caused by oxidation or heat in addition to deterioration caused by the inclusion of foreign matter such as iron powder, in a short period of time using a small amount of grease. [Means for solving the problem]

[0009] The above object of the present invention is achieved by the following rolling bearing configuration [1].

[0010] [1] A rolling element is held between the outer ring and the inner ring so that it can roll freely, and A rolling bearing filled with a grease composition containing a temperature indicator.

[0011] Further, preferred embodiments of the present invention relating to the rolling bearing relate to the following [2] to [9].

[0012] [2] The rolling bearing according to [1], wherein the grease composition has a worked penetration (25°C) of 240 or less. [3] The rolling bearing according to [1], wherein the thermal conductivity of the grease composition is 150 mW / (m·K) or less. [4] The rolling bearing according to [1], wherein the amount of the grease composition filled is 30% by volume or more of the internal space of the bearing. [5] The rolling bearing according to [1], wherein the thickener of the grease composition is a urea compound. [6] The rolling bearing according to [1], wherein the base oil of the grease composition is a mineral oil or a poly-α-olefin oil. [7] The rolling bearing according to [6], wherein the temperature indicator is dissolved in the base oil. [8] The rolling bearing according to [6], wherein the temperature indicator is dispersed in the base oil. [9] The rolling bearing according to [1], wherein the temperature indicator is encapsulated in microcapsules. [Effects of the Invention]

[0013] According to the rolling bearing of the present invention, the temperature indicator in the grease composition changes color at a certain temperature, allowing the deterioration of the grease composition to be visually recognized from the outside, making it possible to detect the deterioration in a short period of time using a small amount of grease. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a rolling bearing (ball bearing) of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in detail below with reference to the drawings. However, this embodiment shows an example of the present invention, and the present invention is not limited to this embodiment. Various changes or improvements can be made, and forms with such changes or improvements can also be included in the present invention.

[0016] FIG. 1 is a cross-sectional view showing a ball bearing, one embodiment of the rolling bearing of the present invention. As shown in the figure, ball bearing (rolling bearing) 1 is configured by holding a plurality of balls (rolling elements) 13 in a freely rollable manner between an inner ring 10 and an outer ring 11 by a cage 12. The internal space of the bearing is filled (sealed) with a grease composition G containing a temperature indicator. Note that ball bearing (rolling bearing) 1 may or may not be equipped with a sealing member 14. Note that if ball bearing (rolling bearing) 1 is equipped with a sealing member 14, it is preferable that sealing member 14 be transparent, translucent, or slightly opaque so that the color of the temperature indicator contained in grease composition G can be effectively seen.

[0017] Grease composition G contains a base oil, a thickener, and a temperature indicator. The term "temperature indicator" as used herein refers to a substance that irreversibly changes color (changes hue) when heated to a certain temperature or higher. Examples of such a substance include 3,6-dimethoxyfluoran (yellow), 3-cyclohexylamino-6-chlorofluoran (orange), 3-diethylamino-6-methyl-7-chlorofluoran (vermilion), 3-diethylaminobenzfluoran (pink), rhodamine B lactam (red), crystal violet lactone (blue), 3-diethylamino-7-dibenzylaminofluoran (green), and 3-diethylamino-6-methyl-7-anilinofluoran (black).

[0018] The temperature indicator may be dissolved in the base oil or may be dispersed in the base oil as particles without dissolving. The dissolved or dispersed state depends on the combination of the temperature indicator and base oil. When the temperature indicator is dissolved in the base oil, the acoustic characteristics of the bearing are improved. On the other hand, when the temperature indicator is dispersed in the base oil, it can be selected regardless of the base oil, thickener, and other additives that make up the grease composition.

[0019] The temperature indicator may also be encapsulated in microcapsules and dispersed in the base oil. The microcapsules can prevent deterioration of the temperature indicator. The microcapsules may dissolve when the temperature of the grease composition G rises, or may remain undissolved. The microcapsules are preferably transparent, translucent, or slightly opaque so that the color of the temperature indicator can be visually confirmed.

[0020] There are no limitations on the other ingredients in the grease composition G, but it is preferable to use a mineral oil or a poly-α-olefin oil as the base oil, and either of these can be appropriately selected from those conventionally used in grease compositions.

[0021] Although there are no limitations on the thickener, it is preferable to use a urea compound, and those that have been conventionally used in grease compositions can be appropriately selected. Urea-based grease compositions are white, which makes it easier to visually recognize the color of the temperature indicator.

[0022] Depending on the purpose, various additives may be added, such as antioxidants, rust inhibitors, extreme pressure agents, friction modifiers, and pH adjusters.

[0023] The harder the grease composition G, the lower the fluidity in the bearing interior space and the less adhesion to the seal member 14. This allows the temperature distribution, such as which parts of the bearing are hotter, to be clearly determined, and also makes it possible to determine changes (history) in the temperature distribution. Specifically, the worked penetration (25°C) of the grease composition is preferably 240 or less. This worked penetration can be achieved by adjusting the mixing ratio of the base oil and the thickener.

[0024] Furthermore, it is preferable that the grease composition G has low thermal conductivity. When thermal conductivity is low, the hotter parts of the bearing become more clearly visible. Specifically, a thermal conductivity of 150 mW / (m·K) or less is preferable. On the other hand, when thermal conductivity is high, the color hue may change throughout the grease, making it difficult to see the temperature distribution.

[0025] The mineral oils and poly-α-olefin oils preferred as base oils and the urea compounds preferred as thickeners described above can satisfy such requirements for worked penetration and thermal conductivity.

[0026] The larger the amount of grease composition G filled, the better, and it is preferably 30% by volume or more, and more preferably 50% by volume or more, of the bearing internal space. Note that if the amount of grease composition G filled is small, there will be areas where the grease composition G does not reach all over, and the temperature indicator may not act in those areas. [Explanation of symbols]

[0027] 1. Ball bearings (rolling bearings) 10. Inner Circle 11 Outer ring 12 Cage 13 Ball (rolling element) 14 Sealing material Grease composition

Claims

1. A bearing in which rolling elements are held between an outer ring and an inner ring so as to be freely rollable, and A rolling bearing filled with a grease composition containing a temperature indicator, The rolling bearing, wherein the thermal conductivity of the grease composition is 150 mW / (m·K) or less.

2. A bearing in which rolling elements are held between an outer ring and an inner ring so as to be freely rollable, and A rolling bearing filled with a grease composition containing a temperature indicator, the base oil of the grease composition is a mineral oil or a poly-α-olefin oil; The temperature indicator is dissolved in the base oil.

3. A bearing in which rolling elements are held between an outer ring and an inner ring so as to be freely rollable, and A rolling bearing filled with a grease composition containing a temperature indicator, the base oil of the grease composition is a mineral oil or a poly-α-olefin oil; The rolling bearing, wherein the temperature indicator is dispersed in the base oil.

4. 4. The rolling bearing according to claim 1, wherein the grease composition has a worked penetration (25° C.) of 240 or less.

5. 4. The rolling bearing according to claim 1, wherein the amount of the grease composition filled is 30% by volume or more of the internal space of the bearing.

6. 4. The rolling bearing according to claim 1, wherein the thickener of the grease composition is a urea compound.

Images