Rolling bearings

Abstract

To suppress the deviation of lubricating oil in the axial direction in a rolling bearing in an annular space of which action is generated on the lubricating oil to move from one axial side to the other side.SOLUTION: A rolling bearing 20 includes an inner ring 21, an outer ring 22, and a plurality of balls 23 provided in an annular space 29 formed between the inner ring 21 and the outer ring 22, and in the annular space 29, action is generated on lubricating oil 13 to move from one axial side to the other side. The rolling bearing 20 further includes first lubricating oil supply devices 1A, 1B having porous bodies 10 impregnated with the lubricating oil 13 for supplying the lubricating oil 13 from the porous bodes 10 to the annular space 29, respectively, the first lubricating oil supply devices 1A, 1B including a first porous body 10A provided on one axial side of the annular space 29 and a second porous body 10B provided on the other axial side of the annular space 29, as the porous bodies 10, the second porous body 10B having higher capability of supplying the lubricating oil 13 than the first porous body 10A.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to rolling bearings. [Background technology]

[0002] Patent Document 1 discloses a rolling bearing in which an action (pumping action) occurs that directs grease from one axial side to the other in the annular space formed between the inner ring and the outer ring. In this rolling bearing, the pumping action occurs due to the shoulder-dropped shapes of the inner ring and the outer ring. In addition, in this rolling bearing, the pumping action is actively generated by providing an inclined groove (airflow generating portion) in the cage.

[0003] In the rolling bearing, grease is applied in advance to one axial side of the annular space in anticipation of the pumping action, and therefore, in the rolling bearing, the pumping action can supply the lubricating oil (base oil) contained in the grease to the entire annular space from one axial side to the other. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-162815 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the rolling bearing, the lubricating oil is collected on the other axial side of the annular space by the pump action, so that the amount of lubricating oil on the other axial side of the annular space increases with an increase in operating time.

[0006] Therefore, an object of the present disclosure is to suppress bias of lubricating oil in the axial direction in a rolling bearing in which lubricating oil acts to flow from one axial side to the other in an annular space. [Means for solving the problem]

[0007] A rolling bearing according to one embodiment of the present disclosure comprises an inner ring, an outer ring, and a number of rolling elements provided in an annular space formed between the inner ring and the outer ring, and is a rolling bearing in which a lubricating oil acts in the annular space from one axial side to the other axial side, the rolling bearing having a porous body impregnated with the lubricating oil and a lubricating oil supplying device that supplies the lubricating oil from the porous body to the annular space, the lubricating oil supplying device having as its porous bodies a first porous body provided on one axial side of the annular space and a second porous body provided on the other axial side of the annular space, and the second porous body has a higher lubricating oil supplying capacity than the first porous body. Effect of the Invention

[0008] According to the present disclosure, in a rolling bearing in which lubricating oil acts in an annular space from one axial side to the other, bias of the lubricating oil in the axial direction can be suppressed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a first rolling bearing equipped with a lubricant oil supplying device. [Diagram 2] FIG. 2 is a schematic diagram of the lubricant oil supplying device according to the first embodiment. [Diagram 3] FIG. 3 is a schematic diagram of the lubricant oil supplying device according to the first embodiment in a state in which the device is impregnated with lubricant oil. [Figure 4] FIG. 4 is a schematic diagram of a lubricant oil supplying device according to the second embodiment. [Figure 5A] FIG. 5A is a graph showing the relationship between the average pore size of a porous body and the amount of lubricating oil supplied. [Figure 5B] FIG. 5B is a diagram showing the relationship between the porosity of the porous body and the amount of lubricant oil supplied. [Figure 6] FIG. 6 is a schematic diagram showing a second rolling bearing equipped with a lubricant oil supplying device. [Figure 7] FIG. 7 is a schematic diagram showing a third rolling bearing provided with a lubricant oil supplying device. [Figure 8] FIG. 8 is a schematic diagram showing a fourth rolling bearing provided with a lubricant oil supplying device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Overview of the embodiment of the present disclosure> Below, an overview of the embodiments of the present disclosure will be listed and described. (1) The rolling bearing of this embodiment comprises an inner ring, an outer ring, and a number of rolling elements provided in an annular space formed between the inner ring and the outer ring, and is a rolling bearing in which a lubricating oil acts in the annular space from one axial side to the other side, the rolling bearing having a porous body impregnated with the lubricating oil and a lubricating oil supplying device that supplies the lubricating oil from the porous body to the annular space, the lubricating oil supplying device having, as the porous bodies, a first porous body provided on one axial side of the annular space and a second porous body provided on the other axial side of the annular space, and the second porous body has a higher lubricating oil supplying capacity than the first porous body.

[0011] According to the rolling bearing of this embodiment, the amount of lubricating oil supplied to the annular space from the other axial side can be made larger than the amount of lubricating oil supplied from the one axial side. This allows the lubricating oil supply device to generate a flow of lubricating oil from the other axial side to the one side in the annular space. In addition, in a rolling bearing in which the lubricating oil acts from the one axial side to the other side, it is possible to prevent the lubricating oil from being biased toward the other axial side of the annular space. In other words, according to the rolling bearing of this embodiment, it is possible to prevent uneven supply of lubricating oil in the annular space in the axial direction.

[0012] (2) Preferably, the lubricating oil supplying device has the porous body to which grease containing the lubricating oil is applied. In this case, in a rolling bearing equipped with a lubricating oil supply device that uses grease, the amount of lubricating oil supplied to the annular space from the other axial side can be made greater than the amount of lubricating oil supplied from one axial side.

[0013] (3) Also, preferably, the first porous body has a first average pore diameter, and the second porous body has a second average pore diameter larger than the first average pore diameter. In this case, the amount of lubricating oil supplied from the second porous body to the annular space can be made larger than the amount of lubricating oil supplied from the first porous body to the annular space, whereby the lubricating oil supply device can generate a flow of lubricating oil from the other axial side to one side in the annular space.

[0014] (4) Also, preferably, the first porous body has a first porosity, and the second porous body has a second porosity larger than the first porosity. In this case, the amount of lubricating oil supplied from the second porous body to the annular space can be made larger than the amount of lubricating oil supplied from the first porous body to the annular space, whereby the lubricating oil supply device can generate a flow of lubricating oil from the other axial side to one side in the annular space.

[0015] (5) Furthermore, preferably, the first porous body is provided at an end on one axial side of either the inner ring or the outer ring, and the second porous body is provided at an end on the other axial side. In this case, by providing a porous body at the axial end of the inner ring or the outer ring, the axial dimension of the rolling bearing can be easily reduced, thereby enabling the rolling bearing having the lubricating oil supply device to be configured compactly.

[0016] (6) Preferably, the porous body is provided on one of the inner ring and the outer ring closer to a fixed ring. In this case, the lubricating oil can be stably supplied to the annular space regardless of the rotation of the rotating ring, either the inner ring or the outer ring.

[0017] (7) Also, preferably, the porous body further comprises an annular member fixed to both axial ends on the fixed ring side, and the porous body is disposed between the axial inner side of the annular member and the fixed ring and is sandwiched between the annular member and the fixed ring. In this case, in a rolling bearing equipped with a lubricating oil supply device, a porous body can be easily provided at both axial ends of the fixed ring.

[0018] <Details of the embodiment of the present disclosure> Hereinafter, the details of the embodiments of the present disclosure will be described with reference to the drawings. Note that at least some of the embodiments described below may be combined in any combination.

[0019] [Overall configuration of rolling bearing 20] A rolling bearing according to an embodiment of the present disclosure will be described. FIG. 1 is a schematic diagram of a rolling bearing 20 according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram of a lubricant supplying device according to a first embodiment. FIG. 3 is a schematic diagram of a lubricant supplying device according to a first embodiment in a state in which the lubricant is impregnated. The rolling bearing 20 shown in FIG. 1 is an embodiment of the rolling bearing according to the present disclosure, and includes an inner ring 21, an outer ring 22, a plurality of balls (rolling elements) 23, an annular cage 24, and a pair of lubricant supplying devices 1,1. The rolling bearing 20 according to the present disclosure is an angular ball bearing. In this description, when simply referring to a "rolling bearing 20", a configuration common to the rolling bearings 20 of the embodiments shown below (see FIG. 1 and FIG. 6 to FIG. 8) is described.

[0020] In this disclosure, the terms "axial," "radial," and "circumferential" in the description of the inner ring 21 and the outer ring 22 are defined. The "axial direction" is the direction along the center line of each of the inner ring 21 and the outer ring 22. The axial direction also includes a direction parallel to the center line. The "radial direction" is the direction perpendicular to the center line of each of the inner ring 21 and the outer ring 22. The "circumferential direction" is the direction along a circle centered on the center line of each of the inner ring 21 and the outer ring 22. In each drawing, the center line of the inner ring 21 and the outer ring 22 when they are aligned is designated by the symbol "C."

[0021] The lubricant supplying device 1 shown in FIG. 1 to FIG. 3 is a first embodiment of the lubricant supplying device applied to the rolling bearing 20 of the present disclosure, and includes a porous body 10. Hereinafter, the lubricant supplying device 1 according to the first embodiment will be referred to as the first lubricant supplying device 1. As shown in FIG. 3, the first lubricant supplying device 1 is used in a state in which the porous body 10 is impregnated with the lubricant 13. As the lubricant 13 used in the first lubricant supplying device 1, for example, a lubricant oil that has been conventionally used to lubricate rolling bearings can be adopted, and for example, a base oil contained in grease can be adopted. In this embodiment, both a state in which the porous body 10 is not impregnated with the lubricant 13 (see FIG. 2) and a state in which the porous body 10 is impregnated with the lubricant 13 (see FIG. 3) are referred to as the first lubricant supplying device 1.

[0022] As shown in FIG. 1, in the rolling bearing 20, an inner ring raceway 25 on which balls 23 roll is formed on the outer circumferential surface of the inner ring 21. The inner ring 21 has shoulders 26, 26 on one axial side and the other axial side, sandwiching the inner ring raceway 25. In the following description, the shoulder 26 on one axial side is referred to as a first inner shoulder 26a, and the shoulder 26 on the other axial side is referred to as a second inner shoulder 26b. In this embodiment, the first inner shoulder 26a and the second inner shoulder 26b have the same outer diameter (shoulder diameter). Note that the rolling bearing 20 of this embodiment has an inner ring 21 in which the first inner shoulder 26a and the second inner shoulder 26b have the same outer diameter (shoulder diameter), but the rolling bearing of the present disclosure may have a shape in which the outer diameter of the outer circumferential surface of the inner ring increases overall from one axial side to the other axial side.

[0023] An outer ring raceway 27 on which the balls 23 roll is formed on the inner peripheral surface of the outer ring 22. The balls 23 contact the outer ring raceway 27 at a predetermined contact angle. The outer ring 22 has shoulders 28, 28 on one axial side and the other axial side across the outer ring raceway 27. In the following description, the shoulder 28 on one axial side is referred to as a first outer shoulder 28a, and the shoulder 28 on the other axial side is referred to as a second outer shoulder 28b. In the rolling bearing 20, the inner diameter (shoulder diameter) of the second outer shoulder 28b is larger than the inner diameter (shoulder diameter) of the first outer shoulder 28a. Note that the shape of the outer ring 22 in which the shoulder diameters are different on one axial side and the other axial side, as in this embodiment, can be referred to as a shoulder-drop shape.

[0024] Grooves 31 for fixing the first lubricant oil supplying device 1 are formed at both axial ends of the outer ring 22. The groove 31 formed at one axial end of the first outer shoulder 28a is referred to as the first groove 31a, and the groove 31 formed at the other axial end of the second outer shoulder 28b is referred to as the second groove 31b. The inner circumferential surface of the outer ring 2 has a shape in which the inner diameter increases from one axial end to the other axial end (excluding the areas in which the first groove 31a and the second groove 31b are formed), and the first outer shoulder 28a adjacent to the first groove 31a has the smallest diameter, and the second outer shoulder 28b adjacent to the second groove 31b has the largest diameter.

[0025] Multiple balls 23 are provided in annular space 29 between the inner ring 21 and the outer ring 22, and when the rolling bearing 20 rotates (in this embodiment, when the inner ring 21 rotates), the balls 23 roll in the inner ring raceway 25 and the outer ring raceway 27 while being held by the retainer 24.

[0026] In the rolling bearing 20 shown in Fig. 1, when the inner ring 21 rotates, an action (pumping action) occurs in which the lubricating oil 13 flows from one axial side to the other axial side (from left to right in Fig. 1) in the annular space 29. In the rolling bearing 20 of this embodiment, due to the shoulder-dropping shape of the outer ring 22, an action occurs in which the lubricating oil 13 flows from one axial side (the first outer shoulder 28a side) to the other axial side (the second outer shoulder 28b) along the inner circumferential surface of the outer ring 22. The spin (rotation) of the revolving balls 23 also causes the movement of the lubricating oil 13 in the same direction. This action is particularly strong when the bearing rotates at high speed.

[0027] [First lubricating oil supply device 1] The first lubricant oil supplying device 1 shown in Figures 2 and 3 is a first embodiment of a lubricant oil supplying device that can be used for the rolling bearing 20 of the present disclosure, and has a porous body 10. As shown in Figures 2 and 3, the porous body 10 is a member made of a porous material, and has a first porous portion 11 and a second porous portion 12. In the porous body 10, the first porous portion 11 and the second porous portion 12 are continuous, and a virtual boundary portion 10a is formed between the first porous portion 11 and the second porous portion 12.

[0028] The porous material constituting the porous body 10 is preferably a sintered body, a foam material, or a fiber material. The material of the porous material is preferably a thermoplastic polymer material such as polyethylene, polyamide, polyphenylene sulfide, or a metal material or a ceramic material, and considering heat resistance, a metallic porous material such as a stainless steel alloy, a copper alloy, or a nickel alloy is more preferable. The metallic porous material constituting the porous body 10 is preferably a metallic sintered material formed by sintering metal powder in order to form a large number of continuous pores.

[0029] The first porous portion 11 is a portion that mainly has a function of storing the lubricating oil 13 and also has a function of supplying the lubricating oil 13 to the second porous portion 12. The second porous portion 12 is a portion that mainly has a function of storing the lubricating oil 13 supplied from the first porous portion 11 and also has a function of supplying the lubricating oil 13 to the outside of the porous body 10. In the porous body 10, the first porous portion 11 and the second porous portion 12 are made of porous materials having different properties. Specifically, the first porous portion 11 and the second porous portion 12 have different penetration depths, which will be described below.

[0030] The first porous portion 11 and the second porous portion 12 are composed of porous materials having different penetration depths L calculated by the Lucas-Washburn formula (Formula 1) shown below. The Lucas-Washburn formula is a governing logical formula for capillary action, and according to this formula, the penetration depth L of a liquid in an object can be calculated. The symbols used in Formula 1 are L: penetration depth, r: capillary radius, γ: surface tension, θ: contact angle, t: time, and η: liquid kinetic viscosity.

[0031]

number

[0032] When two members with different penetration depths L are arranged in succession, the liquid impregnated in each member moves to the member with the larger penetration depth L by capillary action. As shown in FIG. 2, in the porous body 10, the second penetration depth L2 of the second porous portion 12 is made larger than the first penetration depth L1 of the first porous portion 11. Therefore, as shown in FIG. 3, in the porous body 10, the lubricating oil 13 (liquid) impregnated in the first porous portion 11 moves across the boundary portion 10a to the second porous portion 12. Then, in the porous body 10, the lubricating oil 13 can be exuded from the second porous portion 12 to the outside. Note that "impregnation" here means a state in which the liquid penetrates into the pores of the porous body 10.

[0033] [How to adjust the penetration depth L] Here, a method for adjusting the penetration depth L of the first porous portion 11 and the second porous portion 12 will be described. As can be seen from the above formula 1, the penetration depth L increases as the capillary radius r increases. In the porous body 10, the pore diameter of the pores formed in the porous body 10 corresponds to the capillary radius r in the above formula 1. For this reason, in the first lubricant oil supplying device 1, the magnitude relationship between the penetration depth L of the first porous portion 11 and the second porous portion 12 is adjusted by adjusting the average pore diameter φ1 of the first porous portion 11 and the average pore diameter φ2 of the second porous portion 12.

[0034] In the first lubricating oil supply device 1 of the present disclosure, the average pore diameter φ2 of the second porous part 12 is made larger than the average pore diameter φ1 of the first porous part 11. For this reason, in the first lubricating oil supply device 1, the second penetration depth L2 of the second porous part 12 is larger than the first penetration depth L1 of the first porous part 11 (L1 < L2). In the porous body 10 configured in this way, the lubricating oil 13 impregnated in the first porous part 11 moves to the second porous part 12 across the boundary part 10a.

[0035] Thus, in the first lubricating oil supply device 1, the first porous part 11 has the first average pore diameter φ1, and the second porous part 12 has the second average pore diameter φ2 that is larger than the first average pore diameter φ1. According to such a first lubricating oil supply device 1, the lubricating oil 13 impregnated in the first porous part 11 can be absorbed into the second porous part 12 by utilizing capillary action. In the first lubricating oil supply device 1, the average pore diameter of the entire porous body 10 is referred to as the overall pore diameter φ3.

[0036] Also, as can be seen from Equation 1, the penetration depth L increases as the surface tension γ increases. The surface tension in the porous body 10 is determined according to the material of the porous body 10. For this reason, in the first lubricating oil supply device 1, by changing the material of each porous material constituting the first porous part 11 and the second porous part 12, the magnitude relationship of the penetration depth L between the first porous part 11 and the second porous part 12 is adjusted.

[0037] In the first lubricating oil supply device 1, the second surface tension γ2 of the porous material constituting the second porous part 12 is made larger than the first surface tension γ1 of the porous material constituting the first porous part 11. When comparing an organic material such as resin with metal, generally the surface tension of the organic material is larger than that of the metal. Therefore, for example, by making the first porous part 11 made of metal and the second porous part 12 made of resin, the second surface tension γ2 can be made larger than the first surface tension γ1. In the porous body 10 configured in this way, since the second penetration depth L2 of the second porous part 12 is larger than the first penetration depth L1 of the first porous part 11 (L1 < L2), the lubricating oil 13 impregnated in the first porous part 11 moves to the second porous part 12 across the boundary part 10a. In other words, the lubricating oil 13 moves from the side of the first porous part 11 made of metal with lower lipophilicity to the side of the second porous part 12 made of resin with higher lipophilicity.

[0038] Thus, in the first lubricating oil supply device 1 of the present disclosure, the first porous part 11 has the first surface tension γ1, and the second porous part 12 has the second surface tension γ2 that is larger than the first surface tension γ1. According to such a first lubricating oil supply device 1, the lubricating oil 13 impregnated in the first porous part 11 can be absorbed into the second porous part 12 by utilizing the capillary phenomenon.

[0039] In the above description, in order to adjust the penetration depth L of the porous body 10, the case where both the capillary radius r (each average pore diameter φ1, φ2) and the surface tension γ (each surface tension γ1, γ2) are adjusted is exemplified. However, in order to adjust the penetration depth L, at least one of the capillary radius r or the surface tension γ may be adjusted.

[0040] The first lubricating oil supply device 1 not only has the function of supplying (releasing) the lubricating oil 13 from the porous body 10, but also has the function of absorbing the surrounding lubricating oil 13 by the porous body 10. The first lubricating oil supply device 1 increases the supply amount of the lubricating oil 13 (the amount oozing out from the porous body 10) as the holding amount of the lubricating oil 13 in the porous body 10 increases, and increases the absorption amount of the lubricating oil 13 as the holding amount of the lubricating oil 13 in the porous body 10 decreases.

[0041] [Porosity] As shown in FIG. 2, in the porous body 10, the first porous portion 11 and the second porous portion 12 have different porosities. The porosity is the ratio of the volume of the pores contained in each of the porous portions 11 and 12 to the volume of each of the porous portions 11 and 12. In the porous body 10, the first porous portion 11 mainly plays a role of storing the lubricating oil 13. For this reason, in the porous body 10, the first porosity X1 of the first porous portion 11 is made larger than the second porosity X2 of the second porous portion 12. With this configuration, the amount of the lubricating oil 13 held per unit volume in the first porous portion 11 can be made larger than that of the second porous portion 12. In the first lubricating oil supplying device 1, the porosity of the porous body 10 as a whole is referred to as the overall porosity X3.

[0042] In the porous body 10, it is preferable that the first porosity X1 and the second porosity X2 have the above-mentioned magnitude relationship, and the total porosity X3 is 50 vol% or more and 90 vol% or less. In the porous body 10, it is preferable that the first porosity X1 is 85 vol% or more and 90 vol% or less. This value of "85 vol% or more and 90 vol% or less" is almost the same as the porosity of the thickener contained in the grease. With this configuration, the first porous portion 11 plays the same role as the thickener, and it is possible to ensure that the first porous portion 11 retains the same amount of lubricating oil 13 as when grease is used. And, it is possible to make the amount of lubricating oil 13 retained in the first porous portion 11 larger than the amount of lubricating oil 13 retained in the second porous portion 12.

[0043] Thus, in the first lubricant oil supplying device 1, the first porous portion 11 has a first porosity X1, and the second porous portion 12 has a second porosity X2 that is smaller than the first porosity X1. In this case, the amount of lubricant oil 13 held per unit volume in the first porous portion 11 can be made larger than that in the second porous portion 12. This makes it easier to ensure the amount of lubricant oil 13 held in the porous body 10.

[0044] In the first lubricant supplying device 1 having such a configuration, the lubricant 13 impregnated in the first porous portion 11 can be absorbed into the second porous portion 12 by utilizing the capillary phenomenon. In addition, in the first lubricant supplying device 1, the first porous portion 11 and the second porous portion 12 can play the same role as a thickener in grease and retain the lubricant 13 in the porous body 10. This makes it possible to supply the lubricant 13 stored in the first porous portion 11 to the second porous portion 12 and supply the lubricant 13 from the second porous portion 12 to a target portion without using grease.

[0045] [Second lubricating oil supply device 2] FIG. 4 shows a lubricant supplying device 2 according to a second embodiment. Hereinafter, the lubricant supplying device 2 according to the second embodiment will be referred to as the second lubricant supplying device 2. In the rolling bearing 20 of the present disclosure, the second lubricant supplying device 2 may be applied instead of the first lubricant supplying device 1. The second lubricant supplying device 2 shown in FIG. 4 is a second embodiment of the lubricant supplying device, and has a porous body 15. The second lubricant supplying device 2 is used in a state in which the grease 16 is applied to a single porous body 15. In this embodiment, both a state in which the grease 16 is applied to the porous body 15 (see FIG. 4) and a state in which the grease 16 is not applied to the porous body 15 (not shown) are referred to as the second lubricant supplying device 2. The porous body 15 absorbs the lubricant (base oil) 13 contained in the grease 16 from the grease 16. In other words, the lubricant 13 is impregnated into the porous body 15 by applying the grease 16 to the porous body 15. In the second lubricant oil supplying device 2, the average pore diameter of the porous body 15 as a whole is referred to as the overall pore diameter φ4. In the second lubricant oil supplying device 2, the porosity of the porous body 15 as a whole is referred to as the overall porosity X4.

[0046] In the second lubricant oil supplying device 2, the lubricant oil 13 can be exuded from the porous body 15 to the outside. The second lubricant oil supplying device 2 not only has a function of supplying (releasing) the lubricant oil 13 from the porous body 15, but also has a function of absorbing the surrounding lubricant oil 13 by the porous body 15. In the second lubricant oil supplying device 2, the supply amount of the lubricant oil 13 (the amount exuding from the porous body 15) increases as the amount of the lubricant oil 13 held in the porous body 15 increases, and the absorption amount of the lubricant oil 13 increases as the amount of the lubricant oil 13 held in the porous body 15 decreases.

[0047] [Amount of lubricant supplied from porous material] Here, the amount of lubricating oil supplied from the porous body will be described. Fig. 5A is a diagram showing the relationship between the average pore size of the porous body and the amount of lubricating oil supplied. Fig. 5B is a diagram showing the relationship between the porosity of the porous body and the amount of lubricating oil supplied.

[0048] [Average pore diameter] Figure 5A shows the results of an experiment to investigate the difference in the amount of lubricant supplied depending on the average pore size of the porous body. In this experiment, three types of porous bodies (A to C) with different average pore sizes were prepared, and the amount of lubricant supplied was measured for each of these porous bodies. The three types of porous bodies used in this experiment each have a different average pore size: A) 80 μm, B) 130 μm, and C) 200 μm. These porous bodies (A to C) have a common porosity of 90%.

[0049] As shown in Fig. 5A, among the three types of porous bodies (A to C), porous body C supplied the most lubricating oil, and porous body A supplied the least amount of lubricating oil. The results of this experiment showed that the larger the average pore diameter of the porous body, the higher the lubricating oil supply capacity.

[0050] [Porosity] Figure 5B shows the results of an experiment to investigate the difference in the amount of lubricant supplied due to differences in the porosity of the porous body. In this experiment, two types of porous bodies (D, E) with different average pore sizes were prepared, and the amount of lubricant supplied was measured for each of these porous bodies. The two types of porous bodies used in this experiment had different porosities: D) 50% and E) 65%. These porous bodies (D, E) have a common average pore size of 50 μm.

[0051] As shown in Figure 5B, of the two types of porous bodies (D and E), porous body E supplied more lubricating oil. The results of this experiment showed that the larger the porosity of the porous body, the higher its lubricating oil supply capacity.

[0052] From the results of the above experiments, it was confirmed that in the first lubricant supplying device 1, the supply amount of the lubricant 13 from the porous body 10 can be adjusted by adjusting at least one of the total pore diameter φ3 and the total porosity X3 of the porous body 10. Also, from the results of the above experiments, it was confirmed that in the second lubricant supplying device 2, the supply amount of the lubricant 13 from the porous body 15 can be adjusted by adjusting at least one of the total pore diameter φ4 and the total porosity X4 of the porous body 15.

[0053] [Rolling bearing 20 according to the first embodiment] FIG. 1 shows a rolling bearing 20 according to the first embodiment. In the rolling bearing 20 according to the first embodiment, a pair of first lubricating oil supplying devices 1,1 is provided in each groove portion 31 at both axial ends of the outer ring 22. In the following description, this rolling bearing 20 is referred to as a first rolling bearing 20A. In the first rolling bearing 20A, the pumping action occurs due to the shoulder-drop shape of the outer ring 22. Therefore, in the first rolling bearing 20A, a flow FA1 of lubricating oil 13 occurs in the annular space 29 from one axial side to the other axial side.

[0054] In the first rolling bearing 20A, the first lubricant supplying device 1 (porous body 10) is fitted into the groove portion 31. In the following description, the first lubricant supplying device 1 on one axial side is referred to as the one-side device 1A, and the first lubricant supplying device 1 on the other axial side is referred to as the other-side device 1B. In addition, in this description, the porous body 10 of the one-side device 1A is referred to as the first porous body 10A, and the porous body 10 of the other-side device 1B is referred to as the second porous body 10B. In this description, the total pore diameter φ3 of the first porous body 10A is referred to as the first total pore diameter φ3A, and the total pore diameter φ3 of the second porous body 10B is referred to as the second total pore diameter φ3B. In addition, in this description, the total porosity X3 of the first porous body 10A is referred to as a first total porosity X3A, and the total porosity X3 of the second porous body 10B is referred to as a second total porosity X3B.

[0055] In the first rolling bearing 20A, the porous body 10 constituting each of the devices 1A and 1B has an annular shape. The porous body 10 shown in FIG. 1 has a first porous portion 11 and a second porous portion 12, each of which is annular. The porous portions 11 and 12 are arranged concentrically and are arranged side by side in the axial direction. The porous portions 11 and 12 have the same inner diameter. The outer diameter of the second porous portion 12 is larger than the outer diameter of the first porous portion 11. In the first rolling bearing 20A, the radial outer portion of the second porous portion 12 (the portion whose outer diameter is larger than that of the first porous portion 11) is fitted into the groove portion 31 to fix the porous body 10 to the outer ring 22.

[0056] In the first rolling bearing 20A, the porous body 10 impregnated with the lubricating oil 13 is fixed to the outer ring 22, which is a fixed ring. By fixing the porous body 10 to the outer ring 22 (fixed ring), the lubricating oil 13 can be stably exuded from the porous body 10. In the first rolling bearing 20A, the devices 1A and 1B arranged at both axial ends of the outer ring 22 have the function of preventing the lubricating oil 13 from leaking from the annular space 29 to the outside of the bearing. Note that, although the first rolling bearing 20A shown in FIG. 1 illustrates a case in which the porous body 10 is provided at both axial ends of the outer ring 22 (fixed ring), in the rolling bearing of the present disclosure, the porous body may be provided at both axial ends of the inner ring (rotating ring).

[0057] In this way, in the first rolling bearing 20A, the first porous body 10A is provided at the end (groove portion 31) on one axial side of the outer ring 22, and the second porous body 10B is provided at the end (groove portion 31) on the other axial side of the outer ring 22. In this case, it is easier to reduce the axial dimension of the first rolling bearing 20A compared to the case where the porous body 10 is disposed inside the bearing. Therefore, the first rolling bearing 20A having the first lubricating oil supplying devices 1A, 1B can be configured compactly. In addition, in the first rolling bearing 20A, the porous bodies 10A, 10B are provided on the fixed ring side (outer ring 22 in this embodiment) of the inner ring 21 and the outer ring 22. In this case, the lubricating oil 13 can be stably supplied to the annular space 29 regardless of the rotation of the inner ring 21 (rotating ring).

[0058] In the first lubricant supplying device 1, the lubricant 13 stored in the first porous portion 11 is supplied to the second porous portion 12, and the lubricant 13 can be supplied from the second porous portion 12 to the shoulder portion 28. In the first rolling bearing 20A, the lubricant 13 supplied to the shoulder portions 28, 28 on both axial sides by the first lubricant supplying devices 1, 1 flows along the shoulder portions 28, 28 due to the adsorptive force of the meniscus and reaches the outer ring raceway 27 from both axial sides.

[0059] In the first rolling bearing 20A, the second total pore diameter φ3B of the second porous body 10B is larger than the first total pore diameter φ3A of the first porous body 10A. Therefore, the second porous body 10B has a higher supply capacity for the lubricating oil 13 than the first porous body 10A. Also, in the first rolling bearing 20A, the second total porosity X3B of the second porous body 10B is larger than the first total porosity X3A of the first porous body 10A. Therefore, the second porous body 10B has a higher supply capacity for the lubricating oil 13 than the first porous body 10A.

[0060] In the first rolling bearing 20A, the total porosity X3A, X3B of each of the porous bodies 10A, 10B is set to be 50 vol% or more and 90 vol% or less. In this case, it is possible to ensure the retention amount of the lubricating oil 13 in the first porous body 10A and the second porous body 10B.

[0061] In the first rolling bearing 20A having a pair of devices 1A, 1B having such a configuration, a flow FA2 of the lubricating oil 13 can be generated in the annular space 29 from the other side device 1B toward the one side device 1A. The flow rate of this flow FA2 changes depending on the difference in the amount of the lubricating oil 13 held in each of the porous bodies 10A, 10B. In the first rolling bearing 20A, the flow FA2 of the lubricating oil 13 from the other axial side to the one side can suppress the flow FA1 of the lubricating oil 13 that flows in the annular space 29 from one axial side to the other axial side due to the pump action. In the first rolling bearing 20A, this can suppress the bias of the lubricating oil 13 toward the other axial side in the annular space 29.

[0062] Thus, in the first rolling bearing 20A, the average pore diameter (second total pore diameter φ3B) of the second porous body 10B is larger than the average pore diameter (first total pore diameter φ3A) of the first porous body 10A. In this case, the supply capacity of the lubricating oil 13 from the second porous portion 10B is higher than the supply capacity of the lubricating oil 13 from the first porous body 10A to the annular space 29. Therefore, the supply amount of the lubricating oil 13 from the second porous body 10B can be made larger than the supply amount of the lubricating oil 13 from the first porous body 10A to the annular space 29.

[0063] In the first rolling bearing 20A, the porosity of the second porous body 10B (second total porosity X3B) is greater than the porosity of the first porous body 10A (first total porosity X3A). In this case, the supply capacity of the lubricating oil 13 from the second porous body 10B is greater than the supply capacity of the lubricating oil 13 from the first porous body 10A to the annular space 29. For this reason, the amount of lubricating oil 13 supplied from the second porous body 10B to the annular space 29 can be greater than the amount of lubricating oil 13 supplied from the first porous body 10A to the annular space 29.

[0064] [Rolling bearing 20 according to second embodiment] 6 shows a rolling bearing 20 according to the second embodiment. In the rolling bearing 20 according to the second embodiment, a pair of second lubricating oil supplying devices 2, 2 are provided at both axial ends of the outer ring 22. In the following description, this rolling bearing 20 is referred to as the second rolling bearing 20B. In the second rolling bearing 20B, the pumping action occurs due to the shoulder-dropped shape of the outer ring 22. Therefore, in the second rolling bearing 20B, a flow FB1 of lubricating oil 13 occurs in the annular space 29 from one axial side to the other axial side.

[0065] The second rolling bearing 20B differs from the first rolling bearing 20A (see FIG. 1) in that a second lubricant oil supplying device 2 is used instead of the first lubricant oil supplying device 1. In the second rolling bearing 20B shown in FIG. 6, the same components as those described in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

[0066] 6, a second lubricant oil supplying device 2 (porous body 15) is fitted into each of the grooves 31, 31 on both axial sides. In the following description, the second lubricant oil supplying device 2 on one axial side will be referred to as one-side device 2A, and the second lubricant oil supplying device 2 on the other axial side will be referred to as other-side device 2B.

[0067] In this description, the porous body 15 of the one-side device 2A is referred to as the first porous body 15A, and the porous body 15 of the other-side device 2B is referred to as the second porous body 15B. In this description, the total pore diameter φ4 of the first porous body 15A is referred to as the first total pore diameter φ4A, and the total pore diameter φ4 of the second porous body 15B is referred to as the second total pore diameter φ4B. In this description, the total porosity X4 of the first porous body 15A is referred to as the first total porosity X4A, and the total porosity X4 of the second porous body 15B is referred to as the second total porosity X4B.

[0068] 6, the second rolling bearing 20B uses an annular porous body 15. In the second rolling bearing 20B, the radially outer portion of the porous body 15 is fitted into a groove portion 31, and the porous body 15 is fixed to the outer ring 22.

[0069] In the second rolling bearing 20B, the porous body 15 to which the grease 16 is applied is fixed to the outer ring 22, which is a fixed ring. By fixing the porous body 15 to the outer ring 22 (fixed ring), the lubricating oil 13 can be stably exuded from the porous body 15.

[0070] In the second rolling bearing 20B, the lubricating oil 13 absorbed from the grease 16 by the porous body 15 can be supplied to the shoulders 28, 28 from the porous bodies 15, 15 on both axial sides. In the second rolling bearing 20B, the lubricating oil 13 supplied to the shoulders 28, 28 from the porous bodies 15, 15 flows down the shoulders 28, 28 due to the adsorptive force of the meniscus and reaches the outer ring raceway 27 from both axial sides.

[0071] In the second rolling bearing 20B, the second total pore diameter φ4B of the second porous body 15B is larger than the first total pore diameter φ4A of the first porous body 15A. Therefore, the second porous body 15B has a higher supply capacity for the lubricating oil 13 than the first porous body 15A. Also, in the second rolling bearing 20B, the second total porosity X4B of the second porous body 15B is larger than the first total porosity X4A of the first porous body 15A. Therefore, the second porous body 15B has a higher supply capacity for the lubricating oil 13 than the first porous body 15A.

[0072] In the second rolling bearing 20B, the total porosity X4A, X4B of each of the porous bodies 15A, 15B is set to be 50 vol% or more and 90 vol% or less. In this case, it is possible to ensure the retention amount of the lubricating oil 13 in the first porous body 15A and the second porous body 15B.

[0073] In the second rolling bearing 20B having such a pair of devices 2A, 2B, a flow FB2 of the lubricating oil 13 can be generated from the other side device 2B toward the one side device 2A. The flow rate of this flow FB2 varies depending on the difference in the amount of the lubricating oil 13 held in each of the porous bodies 15A, 15B. In the second rolling bearing 20B, the flow FB2 of the lubricating oil 13 from the other axial side to the one side can suppress the flow FB1 of the lubricating oil 13 that flows from one axial side to the other axial side in the annular space 29 due to the pump action. In the second rolling bearing 20B, this can suppress the bias of the lubricating oil 13 toward the other axial side in the annular space 29.

[0074] In the second rolling bearing 20B, the porous body 15 is disposed at the axial end of the outer ring 22. In this case, it is easier to reduce the axial dimension of the second rolling bearing 20B compared to a case in which the porous body 15 is disposed inside the bearing. For this reason, the second rolling bearing 20B including the second lubricant oil supplying device 2 can be configured compactly.

[0075] Thus, in the second rolling bearing 20B, the average pore diameter (second total pore diameter φ4B) of the second porous body 15B is larger than the average pore diameter (first total pore diameter φ4A) of the first porous body 15A. In this case, the supply capacity of the lubricating oil 13 from the second porous portion 15B is higher than the supply capacity of the lubricating oil 13 from the first porous body 15A to the annular space 29. For this reason, in the second rolling bearing 20B equipped with the second lubricating oil supplying device 2 using the grease 16, the supply amount of the lubricating oil 13 from the other axial side to the annular space 29 can be made larger than the supply amount of the lubricating oil 13 from one axial side.

[0076] In the second rolling bearing 20B, the porosity of the second porous body 15B (second overall porosity X4B) is larger than the porosity of the first porous body 15A (first overall porosity X4A). In this case, the supply capacity of the lubricating oil 13 from the second porous body 15B is higher than the supply capacity of the lubricating oil 13 from the first porous body 15A to the annular space 29. For this reason, in the second rolling bearing 20B equipped with the second lubricating oil supplying device 2 using the grease 16, the supply amount of the lubricating oil 13 from the other axial side to the annular space 29 can be made larger than the supply amount of the lubricating oil 13 from one axial side.

[0077] [Rolling bearing 20 according to third embodiment] FIG. 7 shows a rolling bearing 20 according to a third embodiment. In the rolling bearing 20 according to the third embodiment, the first lubricant supplying device 1 is fixed to both axial ends of the outer ring 22 using annular members 35. The rolling bearing 20 according to the third embodiment differs from the first rolling bearing 20A (see FIG. 1) in the manner in which the first lubricant supplying device 1 is fixed to the outer ring 22. In the following description, this rolling bearing 20 is referred to as a third rolling bearing 20C. In the third rolling bearing 20B shown in FIG. 7, the same components as those described in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

[0078] As shown in FIG. 7, the annular member 35 has an annular portion 35a and an outer peripheral edge portion 35b, each of which is annular. In the annular member 35 of this embodiment, the annular portion 35a is made of metal and has a shape that is substantially L-shaped in a cross section including the center line C. In the annular member 35 of this embodiment, the outer peripheral edge portion 35b is made of elastic resin and has a shape that can be fitted into the groove portion 31. As the annular member 35, for example, a seal member that has been conventionally used to seal the inside of a rolling bearing can be processed and used. In addition, the annular member 35 may be made entirely of metal up to the outer peripheral edge portion 35b.

[0079] In the third rolling bearing 20C, the outer peripheral edge portion 35b is fitted into the groove portions 31 on both axial sides of the outer ring 22, and the annular member 35 is fixed to the outer ring 22. A groove portion 36 is formed between the outer ring 22 and the annular portion 35a of the annular member 35 fixed to the outer ring 22. In the third rolling bearing 20C, the porous body 10 impregnated with the lubricating oil 13 is disposed in the groove portion 36 between the axial inner side of the annular member 35 and the outer ring 22, and the porous body 10 is sandwiched and fixed between the annular portion 35a and the outer ring 22. In this way, in the third rolling bearing 20C, the porous bodies 10A and 10B are disposed at both axial ends of the outer ring 22, which is the fixed ring.

[0080] The annular member 35 is capable of swinging with the annular portion 35a at the end of the outer peripheral edge portion 35b as a fulcrum due to the elasticity of the outer peripheral edge portion 35b. In the third rolling bearing 20C, the groove width of the groove portion 36 (the axial length of the groove portion 36) is changeable. Therefore, when the porous body 10 is fixed to the outer ring 22 using the annular member 35, even if the shape and size of the porous body 10 vary, the porous body 10 can be easily fixed to the outer ring 22 by sandwiching the porous body 10 between the annular portion 35a and the outer ring 22. In addition, even if the porous body 10 is made of an elastic material such as resin and the shape of the porous body 10 is easily deformed, the porous body 10 can be easily fixed to the outer ring 22 by using the annular member 35.

[0081] In this way, the third rolling bearing 20C further includes annular members 35, 35 fixed to both axial ends on the outer ring 22 (fixed ring) side. In the third rolling bearing 20C, the porous bodies 10A, 10B are disposed between the axial inside of the annular member 35 and the outer ring 22, and are sandwiched between the annular member 35 and the outer ring 22. In this case, in the third rolling bearing 20C including the pair of devices 1A, 1B, the porous bodies 10A, 10B can be easily provided at both axial ends of the outer ring 22.

[0082] [Rolling bearing 20 according to fourth embodiment] FIG. 8 shows the rolling bearing 20 according to the fourth embodiment. In the rolling bearing 20 according to the fourth embodiment, the second lubricant supplying device 2 is fixed to both axial ends of the outer ring 22 using annular members 35. The rolling bearing 20 according to the fourth embodiment is different from the second rolling bearing 20B (see FIG. 6) in that the second lubricant supplying device 2 is fixed using annular members 35. The rolling bearing 20 according to the fourth embodiment is also different from the third rolling bearing 20C (see FIG. 7) in that the second lubricant supplying device 2 including the porous body 15 is used. In the following description, the rolling bearing 20 according to the fourth embodiment is referred to as a fourth rolling bearing 20D. In the fourth rolling bearing 20D shown in FIG. 8, the same components as those described in FIG. 6 and FIG. 7 are denoted by the same reference numerals, and the description thereof will be omitted.

[0083] As shown in FIG. 8, in the fourth rolling bearing 20D, the porous body 15 to which the grease 16 is applied is disposed in a groove 36 between the axially inner side of the annular member 35 and the outer ring 22, and the porous body 15 is sandwiched and fixed between the annular portion 35a and the outer ring 22. In this manner, in the fourth rolling bearing 20D, the porous body 15 is disposed at the axial end of the outer ring 22, which is the fixed ring. When the porous body 15 is fixed to the outer ring 22 using the annular member 35, even if there is variation in the shape and size of the porous body 15, the porous body 15 can be easily fixed to the outer ring 22 by sandwiching the porous body 15 between the annular portion 35a and the outer ring 22. In addition, even if the porous body 15 is made of an elastic material such as resin and the shape of the porous body 15 is easily deformed, the porous body 15 can be easily fixed to the outer ring 22 by using the annular member 35.

[0084] In this way, the fourth rolling bearing 20D further includes annular members 35, 35 fixed to both axial ends on the outer ring 22 (fixed ring) side. In the fourth rolling bearing 20D, the porous bodies 15A, 15B are disposed between the axial inside of the annular member 35 and the outer ring 22, and are sandwiched between the annular member 35 and the outer ring 22. In this case, in the fourth rolling bearing 20D including the pair of devices 2A, 2B, the porous bodies 15A, 15B can be easily provided at both axial ends of the outer ring 22.

[0085] Each of the rolling bearings 20A to 20D of the present embodiment described above includes an inner ring 21, an outer ring 22, and a plurality of balls 23 provided in an annular space 29 formed between the inner ring 21 and the outer ring 22, and an action occurs in which the lubricating oil 13 flows from one axial side to the other axial side in the annular space 29. Each of the rolling bearings 20A and 20C includes a porous body 10 impregnated with the lubricating oil 13, and includes first lubricating oil supplying devices 1A and 1B that supply the lubricating oil 13 from the porous body 10 to the annular space 29. Each of the rolling bearings 20B and 20D includes a porous body 15 impregnated with the lubricating oil 13, and includes second lubricating oil supplying devices 2A and 2B that supply the lubricating oil 13 from the porous body 15 to the annular space 29. Each of the devices 1A and 1B has, as the porous body 10, a first porous body 10A provided on one axial side of the annular space 29 and a second porous body 10B provided on the other axial side of the annular space 29, and the second porous body 10B has a higher supply capacity of the lubricating oil 13 than the first porous body 10A. Each of the devices 2A and 2B has, as the porous body 15, a first porous body 15A provided on one axial side of the annular space 29 and a second porous body 15B provided on the other axial side of the annular space 29, and the second porous body 15B has a higher supply capacity of the lubricating oil 13 than the first porous body 15A.

[0086] According to each of the rolling bearings 20A to 20D, the amount of lubricating oil 13 supplied from the other axial side to the annular space 29 can be made larger than the amount of lubricating oil 13 supplied from one axial side. As a result, in the rolling bearing 20 in which the lubricating oil 13 acts from one axial side to the other axial side in the annular space 29, a flow of the lubricating oil 13 from the other axial side to one side (flow FA2 in FIG. 1 and flow FB2 in FIG. 6) can be generated in each of the devices 1A, 1B or each of the devices 2A, 2B. As a result, it is possible to suppress the lubricating oil 13 from being biased toward the other axial side of the annular space 29 in the rolling bearing 20. In other words, according to each of the rolling bearings 20A to 20D of this embodiment, it is possible to suppress uneven supply of the lubricating oil 13 in the annular space 29 in the axial direction.

[0087] In each of the rolling bearings 20A to 20D of this embodiment, an example is shown in which the dropped shoulder shape of the outer ring 22 causes the lubricating oil 13 to move from one axial side to the other (pumping action), but the rolling bearing of the present disclosure may be configured so that the pumping action occurs due to the dropped shoulder shape of the inner ring, or may be configured so that the pumping action occurs due to an inclined groove (airflow generating portion) provided in the retainer.

[0088] The embodiments disclosed herein are illustrative and not restrictive in all respects. The technical scope of the present invention is not limited to the above-described embodiments, and includes all modifications within the scope of the equivalents of the configurations described in the claims. [Explanation of symbols]

[0089] 1 Lubricating oil supply device 10 Porous bodies 10A First porous body 10B Second porous body 10a Boundary 11 First porous part 12 Second porous part 13 Lubricating oil 15 Porous bodies 15A First porous body 15B Second porous body 16 Grease 20 Rolling bearings 20A First Roller Bearing 20B Second rolling bearing 20C No. 3 rolling bearing 20D No. 4 Roller Bearing 21 Inner Circle 22 Outer ring 23 Ball (rolling element) 29 Annular Space 35 Annular member φ3 Overall pore diameter (average pore diameter) φ4 Overall pore diameter (average pore diameter) X3 Total porosity (porosity) X4 Total porosity (porosity)

Claims

1. A rolling bearing comprising an inner ring, an outer ring, and a plurality of rolling elements provided in an annular space formed between the inner ring and the outer ring, wherein a lubricating oil acts in the annular space from one axial side to the other axial side, a lubricant oil supplying device having a porous body impregnated with the lubricant oil and supplying the lubricant oil from the porous body to the annular space; The lubricant oil supplying device has, as the porous body, a first porous body provided on one axial side of the annular space and a second porous body provided on the other axial side of the annular space, the second porous body has a higher lubricating oil supplying capacity than the first porous body, The average pore size of the second porous body is larger than the average pore size of the first porous body, and / or The porosity of the second porous body is greater than the porosity of the first porous body, and / or A rolling bearing, wherein the first porous body is provided at an end on one axial side of either the inner ring or the outer ring, and the second porous body is provided at an end on the other axial side of either the inner ring or the outer ring.

2. The lubricating oil supply device comprises:

2. The rolling bearing according to claim 1, further comprising the porous body to which grease containing the lubricating oil is applied.

3. 3. The rolling bearing according to claim 1, wherein the porous body is provided on one of the inner ring and the outer ring closer to a fixed ring.

4. Further, an annular member is fixed to both axial ends of the fixed wheel side, The porous body is 4. The rolling bearing according to claim 3, wherein the rolling bearing is disposed between an axially inner side of the annular member and the fixed ring, and is sandwiched between the annular member and the fixed ring.

5. A rolling bearing comprising an inner ring, an outer ring, and a plurality of rolling elements provided in an annular space formed between the inner ring and the outer ring, wherein a lubricating oil acts in the annular space from one axial side to the other axial side, a lubricant oil supplying device having a porous body impregnated with the lubricant oil and supplying the lubricant oil from the porous body to the annular space; The lubricant oil supplying device has, as the porous body, a first porous body provided on one axial side of the annular space and a second porous body provided on the other axial side of the annular space, the second porous body has a higher lubricating oil supplying capacity than the first porous body, The porous body is provided on a fixed ring side of the inner ring or the outer ring, Further, an annular member is fixed to both axial ends of the fixed wheel side, The porous body is A rolling bearing disposed between the axially inner side of the annular member and the fixed ring, and sandwiched between the annular member and the fixed ring.

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